Going to the Dark Side

Yamaha FJR Motorcycle Forum

Help Support Yamaha FJR Motorcycle Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

user 213

FJR DarkSider #1
Jun 17, 2005
Reaction score
***Note for people just finding this thread***

If you want to get to the interesting parts and skip all the chatter, here are some suggested posts to read:

Read posts #9, #22, #33, #103, #172(finally mounted a decent tire to ride on), #186, #188, #194, #199(first ride on the new tire), #201, #220, #234(first, wet, day ride), #333(multi-day trip report w/hooning in the twisties included), #337, #401(tire type/spec questions), #405(darksider #2 posts), #415 (13k miles on CT), #428, #434, #445(what to say to a shop for mounting/buying a tire), #481(front tire log info), #483(two up & weight talk), #488(darksider #3 posts).

Readers Digest Condensed version - #9, #22/33 on pg. 2, then skip to #172 on pg. 9 at bottom, #234 on pg. 12, #333 on pg. 17, #401 & 405 on pg. 21, #415, #488 on pg. 25.

Also, a FAQ now exists - FAQ

Start of original thread below.


I read about mounting car tires on bikes years ago. Mostly cruisers and HDs. I even rode an old Pan Head with one way back in the day. More recently I caught some discussion on one of the lists about it and read some more. Recently I decided to give this a try. At least to discover if it would work on the FJR at all.

I bought a used Cooper Zeon ZXS summer performance tire for cheap to test fit and today with DougC's help we mounted the tire and installed it on the bike. Below is a short report and some pics.

Apologies if you get this multiple times. It's going out to different lists.

So, things went fairly well. First off, it's a bitch to mount a stiff performance tire to a moto rim, even with the NoMar tire changer and three people, but it can be done. It takes all the tools you have though.


More tools stuffed in the tire

NoMar in use

And a 205/50-17 does fit on the FJR's 5.5" wheel, and fits on the bike, JUST. I think it just barely rubbed off the tops of some of the lettering on the sidewall with the brake caliper arm. There was about 1/8" clearance to the side stand legs as well. FYI, it rubbed a little when flat. :-( But not so much you couldn't push the bike around.

the bike

Ready to go test ride:


What did I learn? The car tire is wider than the rim, so mounting it requires more effort to get the first bead in the 'valley' of the wheel while you work the second bead on. And since the tire sticks out farther from the wheel, that means it doesn't like to sit flush on the NoMar pads. It's dished pretty good once you have both beads on the wheel. No need to seat the bead with high pressure, they are THERE. Possibly due to the rim design, the tire sticks out at the rim edge more than on a car. Not a problem, just an observation. Think rim protector beads X2.

For dismounting, it's very challenging to get the wheel lip onto the NoMar pad clips and locked in. I had to stand on the wheel spokes to exert enough down force to allow a second person to push the wheel into the pad clips and locked down.

I also learned to check used tires better for damage. :-/ The Cooper tire I bought for testing turned out to have two vertical slits in the side wall. Same side and they didn't leak with the tire inflated and just sitting there. They only leaked when the tire side wall flexed. I got a slow speed test ride in, but couldn't do an 'at speed' test due to the severe leakage.

The Cooper Zeon ZXS has very stiff side walls. It's a summer rated performance tire, so that was expected. Not much flex at 30 psi and one side would lift off the pavement when doing turns. I suspect a softer sidewall all season tire will not be as bad in this regard, but didn't feel it was a deal breaker on it's own, and didn't get the chance to play with different pressures due to the leaks. We could have patched it, but having learned 85% of what I wanted to learn, I didn't feel it was worth the effort to dismount the tire, patch it in two places, (making a total of three inside patches), and re-mount it.

What I noticed in feel is that during slow speed turns you can do everything you always could and it feels fine, traction wise, it's just that you get feedback in the bars when turning. A very noticeable pressure against you. You push left, it wants to keep going left to a tighter turn. You have to hold the bar position you want noticeably. This is parking lot drill speeds though. On the one short ride at faster speeds, (35 mph), I noted that the bar pressure seemed less and wasn't really that big a deal. Again, not a great test, just tooling down the neighborhood and making some swerves and a few turns.

I'm going to go ahead and order a new all season tire and give the Dark Side a try. I now know it will fit on the FJR and while handling is different, it's not so different or bad that I feel unsafe. There is just an adjustment period. I don't think it's a big deal to adjust to the car tire at this point.

I'll post more when I have the all season tire on and have some miles on it.

Last edited by a moderator:
I can't see the profile (heh-heh-heh) so you might want to be careful on sweepers until you get a "feel" for how the rear tire is going to stick (or not) when weight and power are entered into the cornering equation.

Just thinking in type.....I wonder if you could "shape" a motorcycle contour onto the tire (if the tread depth allows) to help with cornering and turn-in?

Who knows, Eric, this could be a 40,000 mile tire (well....80K for the birthday-boy, SkooterG!).

this could be good to know if you found yourself 200 miles from B.F.E. with a car tire as your only option out of tight spot.

Macgyver-on my good man!

Eric, you're a DORK!!!

This is the answer to the question that should never have been asked.

Thanks for the entertainment, though.

Real motorcycle tires are cheap, compared to crashed bikes,

torn-up gear, and possibly a stay in the hospital, or worse.

Real motorcycle tires are cheap, compared to crashed bikes,torn-up gear, and possibly a stay in the hospital, or worse.
;) I'm gonna die! Oh nooooooooo!

It's obviously not something everyone would do or even consider. That's why it's called "the dark side". :)

Why? Why not? It's been done for years by plenty of people. I simply wanted to try it with the FJR. And if it works for me, then I can change the rear tire every 40k or so, instead of every 10k.

Now obviously enough, if you're getting 4k from a sport-touring tire, there is really no point in even thinking about a car tire. However, I don't ride like that. I routinely see 10k out of a rear tire. Still, three sets of tires a year add up in my budget.

And yes SkooterG, I am a Dork! Just taking one for the team. :lol: :lol: :lol: Somebody had to try it eventually.


Uh, was this posted on Friday? I don't get it.

Was there a bet involved? Beer or other alcohol? :)

Love to throw that into a 40 mph exit ramp at 70...actually I'd rather watch you do it. Did you happen to notice what happens to the contact patch when the bike leans? Check out your own picture!

All of you "experts" should lighten up!

IF the man is intelligent, cautious, thinking, capable, able, and willing to try this experiment....knowing Eric, he is all of the above, and more....why not offer other ideas other than:

"You're going to crash!" or "You're going to die!" or "You're stoopid, why do this?"

Love to throw that into a 40 mph exit ramp at 70...actually I'd rather watch you do it.
Actually, I used to ride like that. After a number of issues with diesel fuel and water spillage, sand, gravel, vegetation (leaves or grass), etc., in the apex of various off-ramps I have modified my behavior. YMMV.
Have some of you bothered to see what posts he has made and the contribution of his thought process since 2002 before responding to this post? I seriously doubt it! (Except for Skooter...but he gets a "pass" on his birthday....)


Now, Eric, I still wonder if there are car tires with a more round profile or enough tread on the edge that could be shaped into a more motorcycle friendly profile. I assume you spend a good amount of your riding time in the center 1/2 of the tread so you'd not be losing a great amount of tread life by reshaping the outer 25% on each side. I know you are not an aggressive rider (Though this tire could be waaaayyy fun in a drag race!) but a little "contact patch" help for off-ramps might be something to consider, especially in the PNW where it does get cold and wet.

I've also noticed that when my rear tire gets a flat spot, toward the end of it's tread life, the required turn-in effort is increased. I'd imagine you get the same resistance/feedback with this rather flat-shaped tire on the rear.

Let us know how the experiment plays out.

Last edited by a moderator:
Thanks for the posting and letting us know what works. Looks like a great experiment. Do you think you could shove anymore tools in that tire? lol

Venture riders have been doing this for years. I can understand it a little better on a bike like that, but to each his own....enjoy. B)

Many many riders on the VTX and Valkyrie boards have gone to the darkside with a CT and for a big cruiser with a limited lean angle and comparitively lower top speed I guess I can understand the appeal (although I never subscribed to it). I just really don't get it for the FJR though but if the cost vs. mileage aspect is that potentially attractive to you then I wish you the best of luck and hope that it works out for you. Just be careful.

I am waiting to see him fire up the 1300cc contour cutter.

should be one hell of a smoke show.

Somewhere along the way some "dork" hung a pair of saddle bags on a sport bike and everyone said WTF.

And here we are :D