I have a Trek FX 7.7 and the rear tire is rubbing the frame with 100psi in the tire. Stops rubbing at 96psi. I have 26mm Continental Grand Prix 4 Season tires. The original tires were Bonetrager 24mm(I think). I would not think 2mm would make a difference??? Any suggestions, am I missing something simple and stupid??

Update to the information I posted, new tires are 28mm (went to my receipt, sidewall hard to read), previous tires 25mm. The rub is on the face of the tire, the picture shows with 96psi and not rubbing. One of the comments I received said that specs for my bike said that 25mm tires would fit, I went to Trek website before I posted this question, and could not find that information. I did not realize that going up in width would effect the diameter as well. Sounds like I need to get some new tires.

For some of the other responses I got, 1. Yes the wheel is very slightly out of true, 2. No bulges or anything in the tire, and 3. I carefully checked to make sure the wheel was mounted correctly and straight.

To everybody that responded - THANK YOU!!!

Uploading a picture

enter image description here

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    2mm can make a difference (especially since width measurements are not well standardized), but so can the thickness of the tread. However, do make sure that the axle is properly seated in the dropouts. – Daniel R Hicks Apr 5 '20 at 14:09
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    That model comes in carbon and Al versions, and the carbon frame specs claim that 25mm tires fit. It's Is the top of the tire that is rubbing or the side? Could it be rubbing the inside of the brake caliper and not actually the frame? – bradly Apr 5 '20 at 16:08
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    Stop using that tyre if you don't want to damage the frame. Even if it doesn't rub at 96psi the tyre changes shape dynamically and it will rub at times. – Carel Apr 5 '20 at 18:52
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    I suspect a faulty tire. Have you checked the tire for a bulge. A normal tire should not measurably change size over 4PSI. – mattnz Apr 5 '20 at 19:27
  • Do you have access to calipers? Compare the width of the front and rear tyres (assuming you changed both) – Criggie Apr 5 '20 at 21:04

Three steps: is it rubbing the entire rotation? If not true your wheel. Is it rubbing all the way round but just on one side, fix the dish of your wheel. If it is neither of the above, you need a smaller tyre.

All tyres will expand to a point as you increase the pressure. They will expand less and less as the pressure increases up until the point that they either explode or you destroy the rim.

There is also the question about why you are using more pressure?. Pressures much over 100psi are only faster as the road gets much smoother (dependant on weight of rider and tyre width), that's why they still use pressures towards 200psi on the track, but road pressures have been declining for years. It takes less energy for a tyre to deform than it does to push the entire bicycle up as it encounters a bump in the road.

  • I am using the tire pressure recommended by the shop where I purchased the bike - actually they recommended 110psi rear and 100psi front. I have lowered to 100 rear and 90 front. I am not a racer, I do put 2500-3000 miles on per season. – Gary E Apr 6 '20 at 16:53

Then it's not too much pressure.

That pic does seem to show the tyre over to one side slightly.

Perhaps dishing the wheel to the centre will fix it.

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