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Tire Pressure(6 posts)

Tire Pressureriderbob
Apr 24, 2002 8:40 PM
I just purchased a set of Michelin Axial Pro tires. I noticed that the recommended tire pressure was 110. I thought this was a little high. I have been keeping my tires around 100 PSI. I am 5-11 and 170lbs. Can someone help me out and explain to me what the differences between riding on 110 versus 100 psi. Thanks in advance!

Riderbob
re: Tire Pressurepa rider
Apr 25, 2002 2:23 AM
I give it shot in explaining. They rate 110 psi to say max pressure allowed for tire. You run this pressure to get best rolling resistance. The only drawback is if your use to 100 psi this pressure will seem to ride rough.

My tires take 120 psi and I got use to the feel at that pressure. At 110 psi I seem to go slower, but it feels alot comfortable. If you tour or ride at 13avg to 14 avg pace then 100 psi may be ok.

Most people go max psi becuase of roll resistance and you shouldn't get a flat if you hit a small stone. I find max psi give you better control of the bike if you go through gravel.

I'm a MTB rider and know that less air on road tires do not give you better traction. So if somebody tells you to have less air in you tires when it rains they're full of it. You have better traction having it at the max psi.

This works for MTB tires and those of you who go offroad with your Jeeps to leave air out of tires.

I would put max PSI 110 and ride it for awhile and see if you can feel comfortable with it. Rolls better and you won't get any flats. I pump up my tires before every ride becuase I lose air every two or three days. The only time you need to run less air is summer 95+ degree weather.

The sun expands your tires if you leave the bike sit in the sun. For example; eating at a MCdonalds and you bike is leaning against wall with sun beaming onto it. Last year I did a trip with friends, in kentucky, and my buddies tires exploded because he was at max psi and it was 99 degrees when we stopped for food.

Heat expands your tires and thats why you don't put max psi in 95 degree and above weather.

Hopes this helps. Sorry for being so winded.

Emory
re: Tire PressureSteveO
Apr 25, 2002 4:23 AM
increased pressure may reduce the chance of pinch flats, but increases the chance of punctures (try popping a maxed balloon vs a slightly deflated balloon).

regarding weather, in my experience, you can actually run with MORE pressure in the summertime, as the summertime cold temp is much closer to the operating temp, therefore less expansion will occur while riding (of course, im talking from the practical standpoint of riding, not baking the tires in the sun).
re: Tire Pressure & HeatChen2
Apr 25, 2002 6:35 AM
Sorry but based on my experience (though limited) I don't agree with your post. I've ridden the Hotter'n Hell Hundred three times. It's held in Wichita Falls Texas in late August. The temperature an inch above the pavement has been measured at 120 F. I put 120 psi in my tires at 6 AM when the temperature is about 80. There are a lot of flats on that ride, but from goatheads, not blow-outs. Come on down and try it sometime.
~Al
re: Tire Pressure & Heatpa rider
Apr 25, 2002 9:52 AM
I would have to agree with you Al, but I have other riders in my group who would say I was the culpert. We rode in 99 degree weather and two people had blowouts on the ride where I put max psi in their tires (women if you haven't notice).

I could only figure that I should have put 110 psi or when we stopped for a five minute break and they (the ones who had the flats) didn't have their bikes in the shade.

We only rode 1 mile down the road from that rest stop before the first girl got a flat. Your correct that it's not the tire heat build up, but sunlight directly on the tire.

I've been station at Fort Hood in 1981 and know you don't touch a wrench that sits in sun on a hot day in Texas.

Thanks for verifying that the flats were not because of my tire psi, but hot weather riding tips.
Simple mathKerry
Apr 25, 2002 4:28 PM
The only way that heat could have caused those flats is if the pressure got so high as to literally blow the tire off the rim. Any other kind of flat is not heat induced unless you're willing to make the argument that the tire is more easily punctured when it is hot, and that would have nothing to do with pressure. If you inflated the tires to 110 psi at 80 F, and then they heated up to 140 F in the sun, the pressure would only be up to 122 psi. There's no way that a 12 psi increase would cause a flat unless you were really close to the ragged edge in the first place. And don't expect us to believe that 2 flats in a ride group has some sort of statistical significance. The short answer is, you're believing what you want to believe, but it has no basis in fact.