Darkside FAQ

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user 213

FJR DarkSider #1
Jun 17, 2005
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This thread will be just facts and answers to frequently asked questions. As time allows I will add more data. The hope is that it will provide a useful primer for anyone interested in running a car tire on the back of their FJR w/o them needing to wade though the nearly 4000 posts, (as of 9/14), in the original thread. The original thread can be found HERE

Edit note 5/24/21 - I replaced some pictures with stock tire pics to show tread patterns.  Dead links/pics deleted.

ADMIN NOTE: As this thread is added to by the author and author incorporates details into the first post, they may ask to have posts removed to keep the thread clean and organized.

NOTE - All info equally pertains to Gen I, II & III unless specifically stated otherwise.

**********Motorcycling is a dangerous sport!!! RUNNING A CAR TIRE ON YOUR MOTORCYCLE CAN HAVE INSURANCE REPERCUSSIONS. Claims in tire related accidents have been both denied and accepted. Read your policy and speak with your agent. Be aware of the potential issues and make your own decisions based on your own risks and risk assessment. If you wish to discuss this, start a new thread, don't post it here.

Why put a Car Tire, (CT), on the back of the FJR in the first place?
The prime reasons are cost and longevity. A CT will last 20-40k miles and costs $60-200 depending on your choice of tire. For riders that cover 20-30k+ a year, this results in a significant savings. For some this is the difference between riding more or riding less. It's also an option for riders doing long trips that would otherwise require a mid trip tire change, possibly in an unlikely location such as Alaska. The CT is also more resistant to punctures.

It can also be a viable option if you are stuck somewhere due to tire damage or premature wearing out and can't get a replacement motorcycle tire. This could make it possible for your trip to continue w/o waiting for a tire to be shipped to you in the middle of no where, or a place where there are no motorcycle shops to mount your tire. For this reason, some travelers make their bikes "Car Tire ready" by replacing the brake tension arm prior to their trip.

Doesn't the handling suck?
No. It's different, but not nearly as different as you might expect. The main two things you notice are heavier turn in and a different feel when crossing grooves in the pavement. There is also a tendency to track more in tire ruts. The heavier turn in is quickly gotten used to and a non-issue once muscle memory is developed. For some, this is the end of the block, others need a couple hundred miles to grow accustomed to it.

The main loss with a CT is the quick, effortless transitions that we experience on new moto tires. On moto tires this dimishes as the tires wear, with handling becoming poor at the end of the tire's tread life, (sometimes earlier). With the CT, the handling is consistent throughout the life of the tire. Once the rider is accustomed to the new feel, quick, easy transitions are natural again with no, or little, perceived additional effort. The CT actually offers smoother & easier turn in as it "wears in" to moto use. This takes around 400-1000 miles, depending on tire. Also worth noting is that front tire wear still impacts turn in feel too. A worn front tire will increase turn in effort, just as a squared off rear moto tire contributes to this effect.

Local regulations and vehicle inspections requirements should be investigated to determine the legality and potential liability before mounting and using a car tire on a motorcycle.

Uneven road surfaces, like steps as you move from that newly paved lane to the one not yet re-paved or curb edge transitions can cause the bike to sharply lean, use extra care during this type of maneuver!!

doctorJ wrote - I have found one thing to be aware of with the car tire on the feejer. I sometimes drive up the short inclines (for wheelchair entrance) to park at some storefronts that have cycle parking. This isn't a problem if riden straight up, but when I tried this at an angle, the rear tire "wanted" to follow the degree of the angle of the incline i.e. wanted to lean me downhill. This didn't make me fall over but just got my attention. So if going up these things like I do occasionally, be ready or lean "uphill" or just go up straight.
I know that the capable FJR is up to the challenge, but that tar,I don't know, I don't think so..(can it really handle in the twisties??)
It really does have traction all the way over to peg scraping lean angles. Once the muscle memory is established and you accept that you really can lean just like you did before, there is no problem riding fast in the twisties. It is more work to toss the bike back and forth with the CT. As mentioned above, transitions from side to side require more effort. Once the muscles are built up, it doesn't seem like a big difference, but spending the day in the twisties will usually let you know that you got a work out in the shoulders.

Will I be trading traction and handling for more tire mileage?
No, you will not be giving up any traction. If you brake in, hammer out and live for the twisties, you are giving something up for more tire mileage. Not traction/control, but ease of turn in and feel, both personal things that every rider has to quantify for themselves. Tire choice, even among car tires, does make a big difference! A very general rule of thumb is that if you wear out a sport-touring tire in 4k, you're probably not a candidate for CT use. You'll miss the light turn in effort of fresh moto tires.

But the sidewalls of a CT aren't meant for riding on! Won't this be dangerous?
No. You never ride on the sidewalls of the CT. The dynamics are a little different when using a CT on the motorcycle. For much of the time the full width of the CT tread is on the ground. During low angle turns, all of the tread stays in contact with the pavement and the sidewalls flex to allow this. When turn angles exceed the ability of the sidewalls to flex, the outside tread blocks start to lift off the ground, but the tire does not roll over onto the side wall. The inside tread blocks remain in contact with the pavement. At extreme lean angles the last two tire blocks of the tread are still in contact with the pavement, even in peg dragging turns. There is another dynamic in play at steep angle turns. The rear lifts up, steepening the steering angle, which naturally quickens turn in. However, due to the squarer tread, you don't actually feel this, it's just a smooth transition w/o a peak in effort

Traction is not a limiting factor with the CT. In fact, traction is better than a moto tire in many conditions. The CT does not step out on tar snakes and resists sliding in loose conditions well past the threshold of a moto tire. The greater tread depth and number of tread blocks also helps greatly in dirt/gravel/mud/sand conditions giving a more stable and control-able ride.

Further, the loads and forces involved on the motorcycle are far less than those of a car. Less than half, even at max. load on the FJR. This means less heat, and also means slightly lower tire pressures are desirable for moto use.

Does the car tire lower or raise ride height?
Ride height is usually raised in the rear slightly due to the larger diameter of the CT. It is a relatively small amount, as far as what you notice when sitting on the bike with your feet down at a stop. This facet also accounts for the odo and speedo being closer to accurate with the CT, (the larger diameter).

Will a car tire actually fit on the FJR w/o modifications?
No. The tire fits the stock wheel just fine, but the brake caliper tension arm usually rubs, depending on the tire choice. However, it's a simple piece to replace with a flat steel or stainless steel part that allows plenty of clearance. Some riders have also slightly clearanced the center stand legs, though this is usually not necessary.

How do I make a new brake tension arm?
The stock part is a hollow aluminum tube, likely an extrusion, with lightening holes. A 3/16" thick x 3/4" wide x 9 1/2" long steel or stainless steel flat bar is more than strong enough to replace the stock part. Most well stocked hardware stores will stock this material by the foot. Simply use the stock part as a template to drill the two mounting holes and a third smaller hole for the zip tie that retains the brake line to the bar. Radius the ends to avoid sharp corners and if you use steel, paint it so it won't rust.

Finished length = 9.5" (If you want to get picky, 9 15/32") You need to radius the ends for clearance.

Center to center of the (2) .328" ,(21/64"), mounting holes = 8.563" (or 8 9/16")

Distance of the smaller .243", ('C' drill size), hole, from the END of the bar = 1.157" (or 1 5/32")

Install the new part on the outside of the solid tabs on the swing arm and brake caliper to allow for the additional clearance needed.

An online source for Stainless Type 316 flat stock in 3/6" x 3/4" is HERE Many hardware stores will carry 3/16" x3/4" flat steel stock that can easily be cut and drilled with simple tools at home. Just paint the steel so that it does not rust.

Carmine's Custom Cycle brake bar (above) - Available from FarkleMasters
NOTE - The brake arm is the same for Gen I and II.

Note: Regardless of what brake arm you make or use, compare it to the stock one before mounting it to ensure the holes line up and the length is correct. At least one rider has had an issue with a long bar not fitting and this can cause potential problems, including, but not limited to, ABS failure!

Note that some riders have modified the stock part, either cutting clearance into it, or by cutting it completely in half and using as suggested above, bolted to the outside of the solid tabs. While there have been no reported failures, I really prefer the extra strength of a steel or stainless steel part. You need to make your own judgement call on this.

If I put the Carmine's Brake bar, (or other modified bar), on the FJR, w/o mounting a car tire will there be an issue?
No, there are no negative issues with running a CT brake tension arm with a motorcycle tire. This simply makes the bike "CT ready", but in no way limits you. You can safely run either a moto tire or CT at that point with no further modifications

What size tire fits?
The best size car tire to use is 205/50-17. This size CT is the only 17" size rated for a 5.5" wide rim, (the FJR's size), and offers a wide selection of tire choices.

**Note: As of May 2019 narrower sizes of car tires are becoming available in the US. The Bridgestone Potenza 175/55-17has been run on other motorcycles with excellent results in handling and performance. Not as many tire options in this size.

Why not use a 185 or 195 sized car tire, rather than a 205? Wouldn't a smaller car tire be less expensive, easier to mount, have less rolling resistance and be closer to the original 180 tire size?
The main reasons for this are pretty strait forward. There are no 185 width tires in 17", at least beyond temp spares.** 17" tires tend to be in a performance or grand touring class. They often have squarer profiles, in part to maximize tread life, an in part to improve cornering stability with stiff side walls.

What tire pressure do you use?
This will vary by rider. Many are running 30-32 psi. with the 019 Grid. BugR ran 28 psi on pavement and 25 psi on gravel for the BFG, (which has stiffer sidewalls).

Testing with a temp gauge has shown that for the all season tires 31 psi offers an even temp rise and provides excellent long term wear. Lower pressures will offer easier transition feel, but at the cost of additional wear to the outside tread blocks. Some are running max. pressure for the tire they use, (50 psi), to maintain as much of a rounded profile as possible. (this offers a different feel, but so far appears to not impact tread life, at least at the 10-15k point. Full term wear is still unknown.) Each rider needs to determine what suits their riding style best.

What tires have already been tried?
(pics below are of tires when mounted, not always during use)

The following tires are currently being used on the FJR. Tire choice is a highly individual area. Longevity has not been fully determined at this time, but will be updated as info becomes available. Typically, I chose to look at tires with the following characteristics: Rounded edges, (this makes turn in easier), All Season classification, (summer only tires don't last as long and can sometimes change character in the wet, with poor traction resulting), symmetrical tread designs, (nice, but not a must have, though some asymmetrical tire designs have harder tread blocks on what would be the 'outside' of the tire when used on a car) and non-run flat, (run flat tires have very stiff side walls and this is not desirable for the FJR's weight, increasing turn in effort. Heavier bikes like Goldwings do benefit from Run Flat tires).

Potenza 019G Grid This tire has proven to be a consistent 40k mile tire. It requires more turn in effort than some other tires and has slightly stiffer sidewalls and a slightly more square profile than some other tires, but remains a proven choice that wears evenly.

Bridgestone Potenza 019G Grid

(removed at 36,600 and not quite at the wear bars. Easily a 40k tire)

Yokohama ADVAN A82A
(3/32" left to wear bars at 12k)This tire wears faster than the 019Grid. Only lasted approx. 26k miles. Handled well, turn in pressure was average.

Aurora H107
(used for the '09 IBR with a PR2 - no tire changes or problems.)
May not be available in 205/50-17 at this time.

Michelin Pilot Sport A/S Plus
 (This tire finally hit the wear bars at 55,000 miles! on 11/19/14. It now holds the record for longevity of a car tire on a FJR)

Close up of tread at 55k miles on 11/19/14 Red arrow showing wear bar at tread surface, yellow arrows showing wear bars still very slightly below tread surface.

Yokahama AVS Db (South Africa) Wore out quickly. Approx. 15k miles. It is difficult to find 205/50-17 tires in RSA, limiting the potential choices for Darkside tires.

Dunlop Direzza DZ101 Good feel and handling, wears well, unknown life, but should easily be over 30k.

Michelin Pilot Exalto A/S (This has become one of the most favored tires for it's excellent handling) Note that this tire, as of 9/14, is no longer in production, though some left over stock can be found still. This tire was typically a 36-40k mile tire and due to the more rounded edges, handled very "bike like" with easy turn in and good overall manners.

Goodrich Supersport A/S

Toyo Extensa Hp (about $65)


Yokohama AVID Envigor Report by another rider from 10/13/14 of reaching wear bars at 20k miles.

General Tire GMAX (pic by Frankko) This has become a popular tire choice as of 9/14 and handles well, wears evenly and is inexpensive as well. A proven performer. Mileage life is as yet unknown.

Another potentially good Darkside tire. Not tried yet, so report back if you try it. $76.21 as of 12/12/18

Riken RAPTOR ZR A/S - SIZE: 205/50ZR17 This is an ultra high performance all season tire with a 300AA rating. Symmetric tread design with good wet and dry reviews.


How about adding what cars use this size tire to FAQ? When I ordered my tire this evening, the online store asked for a vehicle.

They do that to suggest other items and it won't affect your ability to buy the tire you want. Enter any car, or a late model Mini Cooper if you want something that takes the 17" size wheel.

What about run flat tires?
Run Flat tires have very stiff sidewalls. This is a good thing for the 900 lb. GL1800, but not necessary for the 650 lb. FJR. Run Flat tires are also much more expensive. One of the reasons for a CT is economy. FWIW, even with zero air pressure the FJR is light enough to ride on the CT w/o collapsing it, though I would not attempt to do this at any significant speed! And inner side wall damage WILL occur if done for any significant distance.

What about shaving the outside corners of the tire to put more of a radius on them?
It has been suggested that a tire re-treader or race shop could possibly do this. It should benefit initial turn in to have this done, though I would suggest not going below 4/32" thread depth during the process. In time, the profile wears naturally, but doesn't seem to diminish the tread depth to the same degree that shaving would. If someone tries this, please let me know and your input will be added to the FAQ.

Aren't CTs different diameters?
Yes, and they vary by brand, (as do moto tires).
A few differences:
OEM FJR rear ('Stone 021) v/s (generic CT) 205/50/17 CT
Overall diameter: 24.8"(moto) v/s 25.1"(ct)
Tread depth: 7/32"(moto) v/s 10/32"(ct)
Weight: 13.7 lbs(moto) v/s 24 lbs(ct)

The FJR speedo and odo are slightly off with stock motorcycle tires. Typically reading ~3-5 mph faster than actual on the speedo. Running a 25.1" diameter CT resulted in my '04 FJR's speedo and odo being exactly correct, verified by multiple GPS testing.

How much heavier are CTs than Moto tires?
(from the Darksider thread, posted by: TravelinLite)
It seems as if you FJR Darksiders are at quite a disadvantage in the tire selection department when it comes to tire weight. From what I could find the 180/55-17 Michelin PR2 weighs between 13-13.5 lbs.

I did some checking on 205/50-17 CTs and came up with the following:
General G-Max = 21lb.
Yokohama ADVAN A82A = 23lb.
BridgestonePotenza RE92A = 23lb.
DunlopSP Sport 7000 A/S = 23lb.
Falken ZIEX-912 = 23lb.
Toyo Proxes 4 Plus = 22lb.

Does the heavier CT cause any issues?
The extra unsprung weight creates a little more work for the rear shock. If the shock is worn, it will become more obvious with the additional weight working the shock harder. Running an aftermarket shock, I have not noticed any need to rebuild any sooner than normal with the CT. The extra weight does impact Hp to a minor degree. The extra mass of the tire sucks up some power during acceleration. Riding back to back identical FJRs, with and w/o CT, makes it apparent that only a slight loss in acceleration is noticeable.

Is it a problem to get a CT mounted on the FJR rim?
This varies widely. Some moto shops will mount the CT w/o issues. (Cycle Gear seems to be ok in some locations), HD and trike oriented private shops also seem to be generally ok with it. Most car tire sellers can do it, but may not like the idea. A rim clamp tire changer is required for the job, which is common at any tire shop dealing in high end alloy wheels. Some tire changers have too large a center pilot rod for the FJR's wheel. America's Tire has been great, but can't balance the mounted tire due to their equipment. I've simply had them mount the tire for my "trike" and then had a moto shop balance it. Oddly, moto shops seem to have no issue with balancing the CT that's already mounted.

Generally, it's a good idea to take just the loose wheel into the shop. Giving them a reasonable suggestion that it's for a sidecar equipped motorcycle or trike seems to help in some cases, as that makes sense to them more than running it on a motorcycle.

It can be done on a NoMar or similar manual tire changer too. The main difficulty is getting the second bead on the wheel. The wider CT resists attempts to get the first bead to stay in the 'well' of the wheel. Using small blocks to keep the first bead up into the center valley or well of the wheel helps allow the second bead to shift and that last 1/4 to get over the rim edge. There is enough static pressure on the tire beads that it is very difficult to rotate the tire on the wheel once it's mounted. Seating the bead is a non-issue due to the deeper bead design of the CT. The stiffness of the particular tire's sidewalls has a significant impact on the difficulty of the install. Expect it to be a two man task, even on an automatic machine.

Is it more difficult to push around the garage?
No, no change that I can notice.

What about two up riding with the CT?
Works great. If anything, the additional weight of a passenger keeps even more tread on the ground. Passengers report no change in feel.

Are you sure you haven't died in a horrible, flaming explosion of plastic and aluminum yet?
Yes, I'm sure.
Not so much as a parking lot drop in over 70k miles. And collectively, the FJR Darksiders have well over 1 million miles with no CT related accidents.


OCfjr - Darksider #1 *Sold bike.
BugR - Darksider #2 (Canadian #1)
Doug555 - #3
Coastalcop - #4 *Sold bike.
Catfish - #5
Carmine - #6
Larry33319 - #7
tbwrench - #8
Ian - #9
Smokey2255 - #10 (Smokey's non forum friend #10.5)
Dangerdog - #11
Motofrank - #12
Demetri - #13
Fester - #14
RadioHowie - #15
Brodie - #16
Udjeni - #1SA
BPFowler - #17
wfooshee - #18
Meosborn - #19
Longrider - #20
Ed Grant - #21
LDRyder - #22 *Used for trip, changed back. Sold bike.
dupontrob2000 - #24
BigD - Darksider #25
Popee - #26
HazzMatt - #27
Bustanut Joker - #28
Hammer - #29
Mattster31 - #30
fjrob1300 - #31
juniorfjr - #32
Poorbob - #33
Spook - #34
Kirrilian - #35
RaYzerman19 - #36
tripntx - #37
georgee2 - #38
alchemy - #39
doctorj - #40
Floridave -#41
Roy Epperson - #42
TriggerT - $43
garyahouse - #44
LowAndSilent - #45 *Changes back and forth.
wpbfjr - #46
RPAETZ - #47
Scott Witherow - #48
aroostook - #49
Tonyducks - #50
RossKean - #51 *Returned to Moto tire, prefers feel after trying 2 tires and 40k of DS riding. Remains Darkside ready for emergencies during trips.
SkooterG - Darksider #52 *Has multiple FJRs, extra Darkside wheels.
Patriot - #53
BullCBX - #54
pmspaul - #55
vectervp1 - #56
jasonhc73 - #57
Specter - #58
qkslver - #59
TripperMike - #60
Dougc - Darksider #61 *Original Darksider Enabler.
txvoyager - #62
Pimp Daddy Blue & Yellow - (honorary) Darksider #63
rbentnail - #64
philellis 123 - #65
Slosey - #66
Justin - #67
SFCJCA - #68
RiderX - Darksider #69
yessirrom - #70
BikerGeek99 - #71
Chuck35 - #72
bgross - #73
ABCindy - #74
FJRGuy - #75
Frankko - #76
mgilles0 - #77 ( First Gen III )
RFlagg42 - #78
Lawrence - #79
odot - #80 (Double Darksider #2)
Pterodactyl - #81
tdperry - #82
Twigg - Darksider #83
FJRay - #84
myrwon - #85
bikerbuddha - #86
DaJuice - #87

karstenp - #88

bigjohnsd #89 (sold bike to owsley)

playinatwork - #90 (First recognized Double Darksider - Running a Bridgestone BT-45 130/70/17 rear tire on the front of his FJR)

Kawman10 - #91

owsley - #92

101stpathfinder - #93

Note: Some people have tried the darkside and changed back. Bungie used the CT for an epic Alaska trip, then changed back to a moto tire. LDryder used the CT for a 49++ ride and changed back to a moto tire. Pimp Daddy Blue & Yellow had to borrow a Darkside tire/wheel and brake arm after the complete failure of his PR3 during a critical ride in order to finish the ride. Some riders choose to do this for a specific trip or rally, but still feel the handling of a moto tire is their preference and return to that afterwards. As has always been said, this isn't for everyone, it's simply a possible option and you should carefully consider your needs and preferences as well as the safety concerns and liabilities involved before choosing to try this.

Work in progress. If you have a question, ask it via PM and I'll add it to the FAQ. Thanks!

Last edited by a moderator:
Below is a post from the main Darksiding Thread by FredW, giving a well thought out review of his experience trying the car tire for approx 400 miles. Editorial comments will be inserted in RED that are not FredW's words, but my own response.
Post proclaiming the end of his experiment:

Yep, that's right. I'm throwing in the towel. The compromise in handling is too much for me to give up for the potential upside (to me).

Today was the Covered Bridges ride, and my first real test of the Car Tire, except for prior short rides around my neighborhood. The Bridges ride is just a sedate paced ride through the New England country side that immediately showed me the biggest problem of running a CT on the back (to me).

We have all agreed that no matter which car tire you run there is a certain increase in steering effort, with some being worse than others. With a car tire you need to keep counter-steering pressure on the inside handle bar to stay leaned over in the corner. I believe that this is because as you ride up on the inside of the tire the contact patch moves inside of the centerline of the wheel. Regardless of the physics, it happens.

My big problem is that in New England, smooth road surfaces are far and few between. Which means that the suspension is always working hard while cornering. When I have constant pressure being applied to the bars and start humping bumps the front wheel weights and unweights which makes the steering fluctuate. This is very unsettling. Through the day I could sense the tire beginning to breakdown some, or maybe I was just becoming acclimated? But either way, at the end of the day's ride I pulled the bike into the garage and yanked that POS Car Tire off of the bike and slapped on a new PR2 (the one I got in the warranty claim for the split tire last week).

I have other issues with the car tire, such as when accelerating out of a corner (as I am wont to do in twisties) the tire squirms and slides, probably because it is still so new with very tall tread blocks. That might also be the particular tire I was running. I don't care. I didn't like it and my experiment is over.

To you died in the wool Darksiders: Please do not take this as a personal attack of your choices. We all have different wants and needs. We make our own choices. I feel that I gave this a good shot and learned that this is DEFINITELY not for me.

Post going into greater detail:

I owe the community a more thorough explanation on my experiences. My prior post was made between two group ride days this weekend and I didn't really have enough time to collect and post all of my thoughts. I do that here.

I apologize in advance for the extreme length of the post, longer even than my normal forum regurgitation, but I want to get it all out there and then move along and be done with it (and then I can unsubscribe from this never ending thread
) I have a feeling that only people with a direct interest in Darksiding will be motivated to read through this diatribe. And I have a feeling that I will be unlikely to dissuade anyone that has already made up their mind on the issue. So be it.

To the others. Please feel free to skip over this long post, or give it a negative for excessive verbosity, or whatever you like...

The sliding / slipping sensation that I got was when acceleration briskly from a stop while also cornering somewhat hard. As an example, trying to accelerate away from a stop sign when entering a main road from a 90 degree side road intersection before the oncoming traffic arrives.

I remain uncertain as to the cause of this. It has not been experienced or reported by others.

Disclaimer: Because of the extreme amount of steering input required at any higher pressure, I did have the tire aired down to just 28 lbs when this occurred. That was probably too low, and may have been the cause for the sliding/slipping. Even so, even if there was no slipping I just can't justify the compromises in the way the bike feels to me.

It also isn't about arm strength. I was not getting tired from the amount of steering effort, at least not consciously so. The worst part of the experience for me was the "bump steer" like effect on the front end of having to maintain such a firm, steady pressure and cornering over uneven road surfaces that we invariably have here. I have no doubt that I could have continued along with the CT, eventually become more used to it and gone ahead and worn it down to the nubbins.

I don't want to give the impression that the experience was all bad for me. But in weighing the Pros and the Cons I just could not justify keeping it on there for a second longer (I'll explain why at the end).

Improved straight line traction in all conditions. Easy to understand that.

Much improved ride comfort (softness). It really smooths out the sharp bumps, like concrete highway expansion joints.

Higher load rating: This could be especially important with a pillion and full bags on long trips. If one was ever considering pulling a trailer, I'd want to consider mounting a CT on the tow bike. FWIW - I would never consider towing a trailer myself. If I needed to take that much stuff, personally I'd just drive a car. Maybe a convertible...

Easier to "track stand" the bike at stop lights/signs. Putting a foot down becomes somewhat optional. (not really, but it feels a little like that)

And the biggies: Economy and Longevity, This have been expounded on to no end.

Increased steering effort required. Regardless of the tire used, you will never reach the happy place where you turn into a turn and the bike goes around the corner on the line with no (or little) steering input. This was not all that bad on smooth turns. I felt pretty confident to lean hard so long as I could see all the way through a turn and knew there were no bumps or rips in the pavement on my line. But when the front end hit any irregularities, the weighting and un-weighting of the suspension caused the steering feedback to vary, which made the handlebars want to wobble under the varying pressure. It felt like bump steer, even though the mechanics are different.

Yes, there is increased steering effort with the CT. You will never have that wonderful neutral steering of a new set of moto tires. This is mentioned in the FAQ post above. Some of this weighting and unweighting in the bumpy turns is, I believe, due to the 58k on the stock shock. Some riders running moto tires have replaced the stock shock in as little as 25k miles. At 58k, it's certainly not working as well as it did in it's younger life, but this effect does occur as FredW describes, but perhaps not in as pronounced a manner with a better shock.

FredW adds: When I threw the new rear PR2 on the bike the steering went back to dead nuts perfect again. Of course you would not know that because it hadn't been said before now. There is no increase in turn in or steering effort at all, even with my stock setup and a well worn PR2 up front.

Tendency to follow irregularities. Longitudinal cracks, rain grooves, expanded metal bridges. All tires do this to some extent. Having the big meat on the back end makes it more so. You just need to always be on your toes.

True, but I found it to be something I didn't consciously notice after getting accustomed to the CT. I simply gained new responses to those conditions.

Tendency to "self steer" down hill. Similar to above, but more troublesome. The back roads in New England tend to have very heavy crowning. Probably helps them drain the winter snow melt. This means that to go straight down a road the left side of the CT will have more pressure on the road than the right. That wants to tilt the bike to the right, and if you let go of the bars it would steer off the right side of the road. You have to constantly steer toward the crown of the road just to go straight. Also, unlike in many southern states, they don't always cant the road to the turns. They often maintain the crown through the turns which means that you end up with much higher steering effort required to make left handers. Now thow in a few bumps from #1 above.

Considerably Heavier - Has an effect on the bike's suspension. Some folks say you need to beef up the rear suspension to handle a car tire. At 58 k miles, I still have the stock rear shock and it works just fine (so far, knock on wood). In fact ionbeam, who knows a thing or two about suspensions, and happens to find himself behind me pretty often, has remarked about how well my stock suspension is working when watching me over some typical New England roads (which is to say rough ones).

Worse fuel mileage - Yup. Although I have a very limited data-set to go on, I suggest that by running a big wide car tire at lowish pressures required for use on a bike will produce more rolling resistance, and will result in worse fuel mileage. At 28 psi it was quite appreciable on my bike. I got more than 10% worse mileage than my normal, which historically doesn't vary by more than 2 mpg (except when I'm following Dave in Kentucky!

Most darksiders running 30 psi or above have not noticed a significant decrease in mpg. Over the course of only a couple of tanks of fuel, other variables could have been in play in FredW's case. It is also important to remember that the CT is larger in diameter than the moto tire, causing the odo and speedo to be different, usually closer to actual, rather than reading higher than actual.

More difficult to mount. Either doing it yourself or finding someone that will do it. I think I have the hang of it now, so could do it again more easily. So maybe not such a big negative.

Liability concerns - Whether well founded or not, there is a possibility, albeit remote, that by using a car tire not approved or intended for use on a motorcycle, that one could have legal issues in the event of "something bad" happening.

How all of the above weighs with me personally:

Longevity and Economy are the two biggest pros. Everything else is fluff, IMO.

I do not commute on my bike. I have a company car and, if I even had a commute, the company would not allow me to ride my bike. Some non-sense about increased liability during work hours. But I don't have commute, I work out of my home, so it's pretty much moot. All of my motorcycle riding is strictly for pleasure. If I remove any of the pleasure of the ride, it's a bad deal for me.

I am a Candy Butt Rider (and proud of it). I do not make LD rides, or rallies. I see no pleasure in riding slab for endless hours to cover a given large amount of distance. I often spend all day in the saddle, only stopping for gas and to pee, and at the end of 10-12 hours I might have only covered 400-500 miles and have never touched an interstate. That is the kind of riding that I find pleasurable. I do not understand the people that think LD rides are "fun", but I can appreciate that everybody has different likes and dislikes and they are certainly all equally valid. I'm amazed by some of these LD feats people talk of, not because I couldn't do it. I'm sure that I could, if I were motivated to. I'm amazed because I ask myself, why?


I buy my PR2's (might change to something else next time) online for ~$150 each on sale with free shipping. They are so easy to mount and balance it is trivial (when I am at home) and free. I am getting around 9k miles per rear, not as high as many other folks, because I wear out the sides of them.
A Michelin Exalto is $155 plus $20 shipping (I'd never encourage anyone to run the $120 Yokohama that I tried). It would probably last me the equivalent of three PR2's because I'd also wear out the sides of a CT first. I just don't ride in a straight line very often. It's back to that pleasure thing...

Need to upgrade suspension? Where is the economy of having to buy an aftermarket shock at ~$750-1000, which will from most accounts need to be rebuilt every 30-40 k miles when with motorcycle tires I can happily run the stock shock or somebody else's stock take-off when mine wears out. Again, this is me. I've heard lots of denigration of the stock FJR suspension, but apparently I am not a good enough rider to tell any better. I'm OK with that.

Front tires wearing faster. I can't prove this, but I have no doubt that with all of the required pushing around of the front end that the front tire life has to be reduced. How much? Not sure... but it has to eat into the economy equation somewhat.

The one thing that I really wish I could economically avoid is in having to take off a tire with a more than a thousand miles left on it, which represents 10% or more of the Fred W life of that tire, because we may be leaving on a 3-4 k miles road trip. I think a better slution for this Candy Butt rider is to get myself a second set of wheels.

In retrospect, I was really never a very good candidate for a car tire to begin with. I even voiced such thoughts early on in this very thread, but I didn't want to be one of those "nay-sayers" that shot down the practice out of hand without any first hand experience. I waited for someone up here in the NE to go darkside, to hopefully steal a ride. No such luck. But I also wanted to see just how tough it is to do it yourself.

So, now I've spilled all of my guts. There you have it all. You should be able to see how I can say so definitively that dark-siding is not for me.
And also how I can't say that it is not a bad idea for some others. Other people have other needs and other tolerances. So... ride on you darksiders. Be happy and enjoy your machines. Hopefully we'll share a ride somewhere down the road.

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For those of you who tend to work on your own bike, who have your own tire changing machine - or know someone who has one, mounting a car tire on the back wheel manually isn’t that big of a deal. Unfortunately my NoMar tire changer is not suitable for the overhanging sidewall on these car tires, so I ended up using tire spoons instead.

The following is how I do it…


Getting the tire off the back of the bike can be somewhat of a hassle. Some people put the center stand up on a wood spacer. For a motorcycle tire it works, but for a car tire with a much wider cross section and relatively square tread area the blocks would have to be so high that the bike may fall forward. I use my home made bike hoist to suspend the rear of the bike high enough to facilitate getting the tire out without removing the rear inner fender. Note that the right side exhaust pipe has been removed. Two bolts and it's off.


The first thing to do is to get the air out of the tire by removing the valve core. This lets the tire ‘breathe’ while I work it. Once the air is out you can use your knees to push down on the side wall enough to squirt some soapy water in the bead area. I weigh 220 lbs, however that's not enough oomph to break the bead this way.


I have a bead breaker on my NoMar machine, but I was too lazy to get it out and set up. In this case I put 2 rim protectors in place with a gap large enough to put a block in between when I push the tire away from the rim with the tool. Once the block is in place the rim protector gets moved a bit and another block is wedged in place. Do this for 4 or 5 blocks until the rest of the bead can be pushed off with your knees.

Please note the sheet of wood underneath the wheel to keep it from getting scuffed up from the concrete floor.


With the bead broken and the blocks keeping it aimed down toward the valley, a rim protector can be placed opposite the blocks and a paddle can be used to leverage the bead over the rim. Use your knees and body weight to your advantage. At this point I started using the vegetable based tire lube supplied by my NoMar tire changer kit - Good Stuff !


I ended up using 2 rim protectors and 3 tire paddles to get the bead to where it stayed on the outside of the rim when I pulled them out. Patience - you are dealing with rubber and tension. It will move - slowly, but it will move. Don't rush it.


Use the soapy water ! Don't be stingy with it.

At this point the bead is not trying to pull itself back onto the rim. I used a rim protector and my thin nosed tire iron to persuade the bead further off the rim. This is where finesse counts. Take your time and don't let the Iron damage the rim.


Success !

Notice the string is on the rim protectors? It's there for a reason. It's also a good idea to keep track of your blocks too. Especially when the next tire is going on the rim. DAMHIK


What's left to do now is to extract the rim from the other side of the tire. Use plenty of tire grease, the stuff is worth it's weight in gold.

Also note that I am running the Doran Tire Pressure Monitoring System. That mushroom shaped thing in the valley is the pressure sensor. I choose to run them inside the rim/tire to keep them out of harm's way. I prefer to let the schrader valve keep the air in the tire. If you put it on the outside hanging off the valve stem, make sure you use the metal stem provided in the kit - Do Not install these sensors on a rubber valve stem, they will fail causing rapid deflation. That would ruin your day right quick.



Mounting the tire is pretty much the reverse of removing one. Keep track of whatever tools/blocks/rim protectors you use. Don't do what I did the first time I did this. Wood blocks inside the tire do not help much for balancing the thing. Be sure to clean the rim on the inside - in the valley as well as where the bead seats. Use a kitchen scrubbing pad to cut the dried on spudge. Get the surface clean down to the powder coated surface. Also use plenty of tire lubricant in the areas where it draws across the rim, but try to keep it off the side of the bead where it locks onto the rim. After you get the tire on the rim, expend the effort to wipe off the tire lubricant in this important area - from both the rim and tire.

I goofed on the picture above… I started out with the brake rotor side first. This forced me to put it facing against the plywood on the floor while I worked the second side onto the rim. I had to be very careful to avoid placing any excessive force on that rotor. Next time I will try it the other way.

Total elapsed time was about 1 1/2 hours from breaking the bead to airing up the balanced tire. Not to bad, I think i'm getting better with practice.


I do my own tire changes for my motorcycle. Several years ago before I went to the dark side, I had been running Avon Storms, and the Michelin PR2. I commute a lot of miles, at the time it was around 75 miles a day, mostly freeway work. On the weekends I had my fun in the hills, though many times I traveled several hundred miles south to see my father in the convalescent home. With that kind of use I was getting around 4500 miles on a back tire. Every 7 weeks I had to spoon on another one. It didn’t take long to cost justify buying a NoMar tire changer at $35 mount and balance fee. That helped a little, but the cost of rubber was eating me alive. Many thanks to Eric for pioneering the use of the car tire on the back of these machines. These past 4 years my 2 Exaltos, totaling 72k miles, saved me over $2,000, and I've enjoyed the ride.

I hope this 'How To' helps.


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Thanks for a new tire option Big John.
Added to the FAQ above.

If anyone gives this tire a try, please report back with your impressions of feel and handling compared to what ever you were running before.

FYI, I am running a BFGoodrich g-Force COMP-2 A/S All-Season Radial Tire - 205/50ZR17/XL 93W, $98.74.

Only got 13,000 miles on it so far. Went round trip cross country on it and the rest win WNC back roads.

My first CT on the FJR.

After running two Gmax tires I put the g-force COMP-2 A/S on the bike a couple weeks before my 50cc ride from Santa Cruiz to Jacksonville in September. It ran well, handled just as good as the Gmax, and day to day riding is quite acceptable. At 9600 miles it still looks practically new with no noticeable wear patterns at all.

The best front tires Ive run are the symmetrical about centreline sipe types, such as the Perrelli Angel, the Michelin PR2, and Michelin Road 5. They do show a scalloped wear pattern, however the wear pattern isnt affecting the straight line handling.

I recently ran an Avon Storm and have concluded that its a miserable choice. Within 3000 miles the scalloping was getting deep enough to shake the front end... left-right-left-right-left-right. Its sipe pattern snakes about centreline 6 times around the tire. The more miles the worse the shaking got. Well before I replaced it at 9800 miles it was actually tugging at the handlebars noticeably at speeds under 30mph. Leading edge of the tread block disappeared into the sipe, but the trailing edge still had ok depth.

My current Michelin Road 5 is at 9600 miles, and although showing some scallop wear, it is still in good shape and handles neutral. I expect to see another 5000 miles easily from it.

Keep this in mind when buying front tires on a dark sided bike, but as always... YMMV



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Are you saying that when running the car tire it may be decreasing the mileage of the front tire or did you have the scalloping even with a rear motorcycle tire?

Canadian FJR

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Are you saying that when running the car tire it may be decreasing the mileage of the front tire or did you have the scalloping even with a rear motorcycle tire?
Canadian FJR
Some of it depends on riding style. I found that some fronts scalloped badly regardless of what rear tire, (CT or Moto Tire), while some did seem to have accelerated wear with a CT on the rear. Others have reported faster wear or different front wear while running a CT.

I still find that some fronts just suck in terms of wear pattern while the rear may be fantastic, running moto tires on both ends. In the past, for my riding style, the front tires did not wear any different with a CT than they did with a moto tire. But that experience was with front tires I had run many times before with moto tires and knew were prone to good wear characteristics. As the Tire companies have "updated" their products, we often see less miles from the 'new' versions and sometimes less desirable wear patterns. My PR-2/3/4/4T fronts always wore into a peaked pattern, regardless of what rear tire I was running. Avons tended to scallop more, (except the long gone Azaro), and BT was in between, but end of life usually meant the scalloping got bad enough that I hated the tire and changed it before the wear bars.

One thing for sure, running the CT will accentuate the feel of a worn front tire. Several people, when first going to a CT, complained about poor handling, only to realize that their front was already worn into an odd pattern or scalloped, they just hadn't noticed it so much with the equally worn rear moto tire. Swapping a new tire on the back made the front wear quite noticeable. I suspect this would have been true to a slightly lesser degree with a new moto tire on the back and a worn front as well.

I'm sure Brodie will respond as well.

I was doing a bit of Darksider research for a friend and ran across this tire, Riken Raptor ZRA/S 205/50ZR17 89W, which at $76 from Tire Rack looks like an excellent Darkside addition. Symetrical Tread, Low Load range compared to many other tires should give excellent flexibility, shoulders are less square than most other options, 24#. https://www.tirerack.com/tires/tires.jsp?tireMake=Riken&tireModel=Raptor+ZR+A%2FS&partnum=05WR7RZRAS&vehicleSearch=false&fromCompare1=yes
A member on another forum installed one in October. Said it was stiff and difficult to get on the rim but hasn't reported back on riding characteristics. It looks like it has the tread pattern I like for our southeastern daily rains, similar to the old GMax AS-03.

I ran a potenza grid for 70000 kms. Yes , steering is heavier. But , all in all I'll do it again for my Alaska trip in 2019. I'll likely just carry a second front tire with me . No muss no fuss.

Any concerns with the General Tire GMAX since it is not symmetrical?

EDIT: after looking closer, I think the AS-03s are symmetrical.

Canadian FJR

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After running two Gmax tires I put the g-force COMP-2 A/S on the bike a couple weeks before my 50cc ride from Santa Cruiz to Jacksonville in September. It ran well, handled just as good as the Gmax, and day to day riding is quite acceptable. At 9600 miles it still looks practically new with no noticeable wear patterns at all.
The best front tires Ive run are the symmetrical about centreline sipe types, such as the Perrelli Angel, the Michelin PR2, and Michelin Road 5. They do show a scalloped wear pattern, however the wear pattern isnt affecting the straight line handling.

I recently ran an Avon Storm and have concluded that its a miserable choice. Within 3000 miles the scalloping was getting deep enough to shake the front end... left-right-left-right-left-right. Its sipe pattern snakes about centreline 6 times around the tire. The more miles the worse the shaking got. Well before I replaced it at 9800 miles it was actually tugging at the handlebars noticeably at speeds under 30mph. Leading edge of the tread block disappeared into the sipe, but the trailing edge still had ok depth.

My current Michelin Road 5 is at 9600 miles, and although showing some scallop wear, it is still in good shape and handles neutral. I expect to see another 5000 miles easily from it.

Keep this in mind when buying front tires on a dark sided bike, but as always... YMMV


My 3rd Gmax (a couple AS-03's and now have a AS-05 mounted) is about shot. I was looking at those BFG Comp-2's and saw the BFG Advantage sport with a symmetrical pattern and a higher treadwear rating. I used to run a GYTT on my ST1300 and get 50K.....that was NICE. Need to decide soon.