Originally Posted by
cyccommute
Guy-Lussac law. At a constant volume, P1/T1=P2/T2. T is in Kelvin. Solving for P2, the equation becomes P2=P1T2/T1. Let’s say that T1=293°K (20*C or 70°F), P1 = 100 psi, and T2= 313°K. Plug and chug to get 107psi. Pretty close to ofajen’s estimate.
Similar to above, but using Rankine (degrees Fahrenheit + 460). T starts at 520°R (60°F + 460), heats up to 120°F (= 580°R). Start with P1=100 psi, P2=T2*P1/T1 = 112 psi. If that's enough to blow your tires, you've got a tire problem and shouldn't have started so high (or had that tire on your bike to begin with).
Call me lazy, I've subtracted 32 instead of adding it or multiplied by 5/9 instead of 9/5 too many times to care.