Jump to content


Photo

Tire PSI Rise


  • Please log in to reply
20 replies to this topic

#1 LAF

LAF

    FJR Commander

  • Members++
  • PipPipPipPipPip
  • 1,130 posts
  • Gender:Male
  • Location:Harrisburg, PA
  • Bike: 2010 ABS (Gen II) N. America

Posted 04 April 2012 - 05:53 AM

Never experienced this.

42/42 front/rear PR2's.

Always my front ran lower at temp then the rear, now they are the same? I would see 46-50 on the rear and 44-46 front. Now I am seeing 47 on both no matter riding style. The rear has 8500 on it the front 2000.

I have felt everything at stops and no heat from anything I can tell by feel. I did have a blown rim on front and had to replace it and press bearings in and mount and balance a new tire on front. I have felt against the bearings and they are cool, the hub of the wheel, and anything else I can lay hands or fingers on. I did notice the right rotor was warm, not hot, but the rear was a little warmer so I know it was from using the rear brakes to slow down and park.

Any thoughts that would increase the front tire temp running?

This was in 57-65 degree temps.

#2 mferriter

mferriter

    Occasionally trying to get work done

  • Members++
  • PipPipPipPipPip
  • 1,019 posts
  • Gender:Male
  • Location:Chapel Hill, NC
  • Bike: 2006 ABS AE (Gen II) World

Posted 04 April 2012 - 06:40 AM

Never experienced this.

42/42 front/rear PR2's.

Always my front ran lower at temp then the rear, now they are the same? I would see 46-50 on the rear and 44-46 front. Now I am seeing 47 on both no matter riding style. The rear has 8500 on it the front 2000.

I have felt everything at stops and no heat from anything I can tell by feel. I did have a blown rim on front and had to replace it and press bearings in and mount and balance a new tire on front. I have felt against the bearings and they are cool, the hub of the wheel, and anything else I can lay hands or fingers on. I did notice the right rotor was warm, not hot, but the rear was a little warmer so I know it was from using the rear brakes to slow down and park.

Any thoughts that would increase the front tire temp running?

This was in 57-65 degree temps.



PV=nRT, so P=(nRT)/V

To have the pressure go up, one of the factors on top (n, R, or T) have to increase, or V has to decrease.

My money would be an increase in T. It is getting warmer outside.

You have to compare the current temperature with the temperature it was when you filled the tires.

The tires and the gas with which they are filled also heat up when you ride. The front probably heats up faster than the rear due to the lower mass.

#3 HotRodZilla

HotRodZilla

    Trying To Be Good

  • Members++
  • PipPipPipPipPip
  • 4,389 posts
  • Gender:Male
  • Location:Albuquerque, NM
  • Bike: 2007 ABS (Gen II) N. America

Posted 04 April 2012 - 06:42 AM

Seriously LAF...Stress less and ride more. Sheesh!
I'd rather go down the river with seven studs than with a hundred shitheads"
- Colonel Charlie Beckwith

#4 mferriter

mferriter

    Occasionally trying to get work done

  • Members++
  • PipPipPipPipPip
  • 1,019 posts
  • Gender:Male
  • Location:Chapel Hill, NC
  • Bike: 2006 ABS AE (Gen II) World

Posted 04 April 2012 - 07:01 AM

Seriously LAF...Stress less and ride more. Sheesh!


I was going to say +1, but thought that might get me in trouble.

So..I agree.

A few PSI +/- shouldn't show much of an effect in terms of handling or mpg. You tire pressure changes all the time when your riding anyway based on temperature.

It would also be a good idea to sheck you tire pressure gauge to make sure it's working properly.

#5 SkooterG

SkooterG

    Purveyor of Crooked Facts

  • Admin
  • PipPipPipPipPipPip
  • 10,981 posts
  • Gender:Male
  • Location:Skootsdale, AZ
  • Bike: 2004 (Gen I) N. America

Posted 04 April 2012 - 07:08 AM

Seriously LAF...Stress less and ride more. Sheesh!


+1

Or..... think less, ride more!
IBA #327........................ Darksider #52

FJR#1 - The 'Dirty Ol Whore' - 2004 non-abs - RIP @ 226,400 - Gone, but not forgotton.
FJR#2 - The 'Hula Girl' - 2004 ABS - 143k
FJR#3 - The 'Virgin' - 2004 ABS - 4344 miles, a garage queen - Brundog would be proud!
FJR#4 - The Oregon FJR - 2004 ABS - 65k
FJR#5 - The Bastard POS Gen II - 2009A - 42k

Posted Image Posted Image Posted Image

#6 mferriter

mferriter

    Occasionally trying to get work done

  • Members++
  • PipPipPipPipPip
  • 1,019 posts
  • Gender:Male
  • Location:Chapel Hill, NC
  • Bike: 2006 ABS AE (Gen II) World

Posted 04 April 2012 - 07:10 AM


Seriously LAF...Stress less and ride more. Sheesh!


+1

Or..... think less, ride more!


Or..... don't think at all and have a beer!

#7 OCfjr

OCfjr

    FJR DarkSider #1

  • Members++
  • PipPipPipPipPip
  • 2,613 posts
  • Gender:Male
  • Location:Ivins, UT USA
  • Bike: Other or considering FJR

Posted 04 April 2012 - 07:12 AM

It would also be a good idea to sheck you tire pressure gauge to make sure it's working properly.


And/Or - check your tire pressures with a gauge, if you are getting this data from a TPMS and see if they match.

'12 Super Tenere


#8 Geezer

Geezer

    Parsimonious Curmudgeon

  • Members++
  • PipPipPipPipPip
  • 5,358 posts
  • Gender:Male
  • Location:Shandaken, NY
  • Bike: 2005 (Gen I) N. America

Posted 04 April 2012 - 07:56 AM


It would also be a good idea to sheck you tire pressure gauge to make sure it's working properly.


And/Or - check your tire pressures with a gauge, if you are getting this data from a TPMS and see if they match.


I was wondering how you were checking the pressure and expecting to get such an accurate consistent measurement. I don't know about TPMS, but a typical tire pressure gauge just isn't that accurate.

'Frodo, It's a dangerous business, going out one's front door'


#9 SLK50

SLK50

    FJR Squadron Leader

  • Members++
  • PipPipPipPip
  • 621 posts
  • Location:Altoona, PA
  • Bike: 2006 ABS (Gen II) World

Posted 04 April 2012 - 08:26 AM



It would also be a good idea to sheck you tire pressure gauge to make sure it's working properly.


And/Or - check your tire pressures with a gauge, if you are getting this data from a TPMS and see if they match.


I was wondering how you were checking the pressure and expecting to get such an accurate consistent measurement. I don't know about TPMS, but a typical tire pressure gauge just isn't that accurate.


Tire pressure gauges are amazingly simple devices. While they may not be accurate they are indeed consistent.
Measurements routinely taken with the same instrument will indicate the even slightest variance.

#10 LAF

LAF

    FJR Commander

  • Members++
  • PipPipPipPipPip
  • 1,130 posts
  • Gender:Male
  • Location:Harrisburg, PA
  • Bike: 2010 ABS (Gen II) N. America

Posted 05 April 2012 - 04:19 AM

Ok guys I am getting old and it is a bitch!

First I consider checking tire PSI while riding an important safety issue. It lets you know if things are ok with the most important part of your bike.

What I did find out is Tuesday morning when I filled and checked the tires it was 50 degrees, but had dropped to 30 or so over night.

Now I though I had 42 and 42 dead on.

After posting I went out to check with the gauge and the front was at 45! It was 62 out.

So dropped it to 42 and left the rear at 43 by the gauge.

150 miles and my rise was up to 49 on the rear and 47 on the front. More what I am used to. You know the 10% rule of PSI rise is something all should pay attention to.

So not sure if I was off on my looking at the gauge or the up and down temps but I am squared away again.

I do have a TPI and am religious about checking as I ride various styles. Running hard through valleys and working the tires, and riding slab just motoring along.

Also tire wear is another thing I am trying to keep at bay by keeping the pressure where it needs to be. Tires are expensive and although I change my own still not something I like to do a whole lot.

Stressed less and I have been riding, as I have put 4500 on in the last six weeks. Had my 8000 three weeks ago and and am ready to schedule my 12,000.

Sorry for the useless post.

#11 SLK50

SLK50

    FJR Squadron Leader

  • Members++
  • PipPipPipPip
  • 621 posts
  • Location:Altoona, PA
  • Bike: 2006 ABS (Gen II) World

Posted 05 April 2012 - 05:05 AM

Ok guys I am getting old and it is a bitch!

First I consider checking tire PSI while riding an important safety issue.

It lets you know if things are ok with the most important part of your bike.

You know the 10% rule of PSI rise is something all should pay attention to.

Sorry for the useless post.


Please excuse my liberal editing.

No post is completely useless, I can't always say the same for the responses. :lol:

#12 SkooterG

SkooterG

    Purveyor of Crooked Facts

  • Admin
  • PipPipPipPipPipPip
  • 10,981 posts
  • Gender:Male
  • Location:Skootsdale, AZ
  • Bike: 2004 (Gen I) N. America

Posted 05 April 2012 - 07:39 AM

Ok guys I am getting old and it is a bitch!

First I consider checking tire PSI while riding an important safety issue. It lets you know if things are ok with the most important part of your bike.

Major snippage......



I don't know about old, but you sir, are most definitely anal-retentive! :lol:

I never check tire pressure while riding. A pre-ride cold tire check of the pressure every now and then and I am good to go.
IBA #327........................ Darksider #52

FJR#1 - The 'Dirty Ol Whore' - 2004 non-abs - RIP @ 226,400 - Gone, but not forgotton.
FJR#2 - The 'Hula Girl' - 2004 ABS - 143k
FJR#3 - The 'Virgin' - 2004 ABS - 4344 miles, a garage queen - Brundog would be proud!
FJR#4 - The Oregon FJR - 2004 ABS - 65k
FJR#5 - The Bastard POS Gen II - 2009A - 42k

Posted Image Posted Image Posted Image

#13 Fred W

Fred W

    Flatus Antiquous

  • Members++
  • PipPipPipPipPipPip
  • 14,243 posts
  • Gender:Male
  • Location:Southern NH
  • Bike: 2005 (Gen I) N. America

Posted 05 April 2012 - 08:32 AM

With the use of a TPMS, riders (and drivers) can monitor their tire pressure (and some aftermarket ones even show temperatures) more or less real time. I don't have one on the bikes yet, but I can see the value of having one installed from my experiences with autos that do.

In the past, picking up some road debris in a tire that results in a slow leak would often go undetected until the pressure was so low that either the handling was negatively impacted or the tire overheated and blew out. Last year I picked up a chunk of steel in one of the tires in the cage. Long before I could even feel the loss in pressure the TPMS was alarming and dinging and telling me I was losing air in that tire. I was able to safely pull off at the next exit and find a safe place to swap on the trunk donut spare.

One thing that I have noticed watching my cage's TPMS is the very phenomenon reported by LAF here. If one of the cage's tires is inflated a couple of psi lower than the others, as you drive the car, all f the tires pressure increase with heating, but the tire with the lower pressure tends to come up more and closer to the pressure of the others. Why?

As mferriter posted, the pressure of a tire is affected by the temperature. But what may not be so obvious is that the temperature of a tire in use is also affected by the pressure. A tire with a lower initial cold pressure will reach a higher temperature while in use. That higher temperature will then have the effect of increasing the tire's pressure.

-Fred W        nerd.gif


 


#14 LAF

LAF

    FJR Commander

  • Members++
  • PipPipPipPipPip
  • 1,130 posts
  • Gender:Male
  • Location:Harrisburg, PA
  • Bike: 2010 ABS (Gen II) N. America

Posted 06 April 2012 - 05:40 AM

With the use of a TPMS, riders (and drivers) can monitor their tire pressure (and some aftermarket ones even show temperatures) more or less real time. I don't have one on the bikes yet, but I can see the value of having one installed from my experiences with autos that do.

In the past, picking up some road debris in a tire that results in a slow leak would often go undetected until the pressure was so low that either the handling was negatively impacted or the tire overheated and blew out. Last year I picked up a chunk of steel in one of the tires in the cage. Long before I could even feel the loss in pressure the TPMS was alarming and dinging and telling me I was losing air in that tire. I was able to safely pull off at the next exit and find a safe place to swap on the trunk donut spare.

One thing that I have noticed watching my cage's TPMS is the very phenomenon reported by LAF here. If one of the cage's tires is inflated a couple of psi lower than the others, as you drive the car, all f the tires pressure increase with heating, but the tire with the lower pressure tends to come up more and closer to the pressure of the others. Why?

As mferriter posted, the pressure of a tire is affected by the temperature. But what may not be so obvious is that the temperature of a tire in use is also affected by the pressure. A tire with a lower initial cold pressure will reach a higher temperature while in use. That higher temperature will then have the effect of increasing the tire's pressure.

This is exactly why I am so anal.

When I hit the rock and blew the rim the TPM was SCREAMING and blinking RED at the instant of impact! I knew I was forked and headed to the shoulder, if that is what it was, very little room off the line and guard rail.

Also picking something up when you only got two tires is pretty high on my list of knowing. If you can know soon enough you may be able to plug it and ride, if not you spin it along until failure or your next air check.

And when going camping for three or four weeks it is nice to see what affect your load has on PSI rise.

Around 10% is the rule I have read. I run higher than that but know it is not way over.

And if you do not believe a "few" PSI makes a difference then that is you. I wonder how your tires last for you, and what they handle like at end of life. Nothing will flat out a rear tire, or cup a front, then low PSI.

Not a jab or poke at anyone to each their own, but tires are damn expensive these days.

#15 mferriter

mferriter

    Occasionally trying to get work done

  • Members++
  • PipPipPipPipPip
  • 1,019 posts
  • Gender:Male
  • Location:Chapel Hill, NC
  • Bike: 2006 ABS AE (Gen II) World

Posted 09 April 2012 - 06:07 AM

Over the course of even a short ride you tire pressure will likely vary by very nearly 10% based on riding style and ambient and road temperature. I can't imagine generating a pressure high enough to cause a blowout if starting from the recommended pressure.

I think blowouts are more often caused by underinflation which leads to excessive tire flexing and overheating of the sidewall.

#16 Fred W

Fred W

    Flatus Antiquous

  • Members++
  • PipPipPipPipPipPip
  • 14,243 posts
  • Gender:Male
  • Location:Southern NH
  • Bike: 2005 (Gen I) N. America

Posted 09 April 2012 - 06:24 AM

I think blowouts are more often caused by underinflation which leads to excessive tire flexing and overheating of the sidewall.


Ding ding ding!! We have a winner. :P


I helped one of the locals (bbdig) install his new Doran 360M TPMS on his Feejer in anticipation of his cross country trip to NAFO this June.
I really like the unit that he got. It seems like it would be a worthwhile investment in safety (to me).

-Fred W        nerd.gif


 


#17 LAF

LAF

    FJR Commander

  • Members++
  • PipPipPipPipPip
  • 1,130 posts
  • Gender:Male
  • Location:Harrisburg, PA
  • Bike: 2010 ABS (Gen II) N. America

Posted 09 April 2012 - 06:27 AM

Over the course of even a short ride you tire pressure will likely vary by very nearly 10% based on riding style and ambient and road temperature. I can't imagine generating a pressure high enough to cause a blowout if starting from the recommended pressure.

I think blowouts are more often caused by underinflation which leads to excessive tire flexing and overheating of the sidewall.

After using a TPM for 6 years or so I do not find this true at all.

Once my tires hit 47 front 49 rear I have never seen them go higher unless I am hauling the mail, and then it may only go another pound but nothing drastic.

I do agree under inflation will cause a blowout due to the issues you mentioned. I start at 42 rear and get to 49 so that is close to 10% rise and I know if it out of those ranges I got a problem. 10% is just a base rise PSI to look for anything a couple of % either way would not be a concern. However I know over several bikes using TPM it is a very repeatable and consistent rise on every bike and PSI I have run on them.

The real question not answered is why will a under inflated tire will rise PSI to match a correctly inflated tire? Be it 2 wheels or 4 as Fred shared in his 4 wheel experience.

#18 Fred W

Fred W

    Flatus Antiquous

  • Members++
  • PipPipPipPipPipPip
  • 14,243 posts
  • Gender:Male
  • Location:Southern NH
  • Bike: 2005 (Gen I) N. America

Posted 09 April 2012 - 06:38 AM

The real question not answered is why will a under inflated tire will rise PSI to match a correctly inflated tire? Be it 2 wheels or 4 as Fred shared in his 4 wheel experience.


I though that was answered already. The tire with the lower initial pressure tire will run hotter, which will raise its pressure up more than a higher (correctly) inflated one. Being that you have a TPMS installed, if you picked up an IR temp gun (a handy tool to have anyway) you could run experiments on this yourself.

-Fred W        nerd.gif


 


#19 Zorlac

Zorlac

    FJR Commander

  • Members++
  • PipPipPipPipPip
  • 1,123 posts
  • Gender:Male
  • Location:Franklinville, NJ
  • Bike: 2005 (Gen I) N. America

Posted 09 April 2012 - 06:29 PM

300psi :glare: :blink:
It makes sense when you don't think about it.

#20 LAF

LAF

    FJR Commander

  • Members++
  • PipPipPipPipPip
  • 1,130 posts
  • Gender:Male
  • Location:Harrisburg, PA
  • Bike: 2010 ABS (Gen II) N. America

Posted 10 April 2012 - 03:44 AM


The real question not answered is why will a under inflated tire will rise PSI to match a correctly inflated tire? Be it 2 wheels or 4 as Fred shared in his 4 wheel experience.


I though that was answered already. The tire with the lower initial pressure tire will run hotter, which will raise its pressure up more than a higher (correctly) inflated one. Being that you have a TPMS installed, if you picked up an IR temp gun (a handy tool to have anyway) you could run experiments on this yourself.

Must have missed that but it makes sense.

I wish Smart Tire still made theirs as they show temp rise also. When I had the opportunity years ago to get a set I was running Ride On religiously. I liked that they were attached in the center of the wheel with a worm clamp. Still inside and if something went south you had to shed the tire to get to it.

That is why I run the Doran and they can also be mounted internal but I choose to keep them outside.

At any rate I think I am ok with my PSI rise as I have seen it in this area on all bikes and tire combos I have run. I think it is a very important to know how much PSI or temp rise you are getting on your tires and something that is overlooked on mileage reports on tires.

I also think it will tell you if 39 or 40 or 42 PSI is working for you, your riding style, and load on the bike. It is all we got to make sure we are taking care of our tires.

I know there is more to tire life then PSI but I think it starts there.