Tire Pressure for 40 degree temp change?

Greg Lewis

Hello All:

I am doing a half next week where the temperature when I can last pump my tires is forecast to be 40 degrees and the temp near the end of the bike is to be 85 degrees. I've never done a race with this wide of a temperature swing. 

I've heard tires popping in T1 and so I typically pump my conti 4000s tires to 110. Is there any thought of how much tire pressure increases when the temperature increases widely? 

Thanks!

 

Brad Marcus

Greg- I'm worried about the same thing next week, so curious to see what responses you get. Worse is that I shipped my bike with bike transport from CT to CA and didn't think to remove some air from the tires - hope they didn't pop!

Al Truscott

A 0.29 second search on Google revealed the following:

http://www.newton.dep.anl.gov/askasci/chem03/chem03261.htm

I have not done the math, but all the equations are there for one to play with if you wish to drive yourself nuts. All I can say is ... I've never had a tire pop in T0, despite all sorts of temperature differentials. Seems to me the key differential is between the time pumped and the time starting to ride. Rise in air temp during ride may be swamped by other factors, including speed, downhills with brakes applied, weight of rider, etc etc. I just go 105/110 F/R, and ride away on the bike leg. Do pro cyclists' wrenches alter tire air pressure when the temp is going sky high on one of those six hour days when they start @ 10 AM and finish @ 4 PM?