availpunk9
09-15-09, 10:48 AM
I have a pair of Vittoia XGs 34mm wide. I'm ran them at 40psi. After practice, I noticed grass lugged between the tire bead and the rim. Am I running too low of a PSI? Is this an indicator that I might pinch flat?
Cyclocross - Tire pressure question
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333foto
09-15-09, 12:52 PM
40 psi sounds a little low ... how much do you weigh? i think i read somewhere the lowest pressure you can run is about 25% of your weight.
availpunk9
09-15-09, 01:37 PM
I'm 176lbs
CatSkratch
09-15-09, 01:43 PM
I used to run low pressures (30psi) and I never got pinch flats but I only weigh 130lbs. Now I run higher pressures (50-55).
CycleAddict510
09-15-09, 01:46 PM
I would guess that when your tire was flexing grass was able to get stuck in there. May also have to do with the width of your rim in relation to the width of the tire. I'm pretty sure this has happened to me before as well but not on the cross bike. With 32's I've run right around 40PSI front and rear with no issues. I usually run the rear up more around 50 recently though. The 25% of your weight method is actually pretty spot on for what I run after doing the math. I say if you aren't denting rims or getting pinch flats, then you're fine.
funurdiesel
09-15-09, 01:57 PM
I wouldn't worry about the grass. If you can run 40 psi and not pinch flat then I don't see any reason to increase the pressure.
333foto
09-15-09, 05:21 PM
I'm 176lbs
try 44 lbs?
try 44 lbs?