This question concerns the gas laws and pressure

Question

A driver fills his tires to 35 psi gauge on a day when the air is 36*C. Over the next few weeks, the temperature drops to -5 degrees C. Determine the new pressure in the tires. Assume the tire volume is constant and that there are no air leaks. State your answer in psi gauge (the pressure is given as gauge pressure).

Answer 1

P1 = initial pressure = 35 psi

T1 = initial temperature = 36ºC + 273 = 309K

P2 = final pressure = ?

T2 = final temperature = -5ºC + 273 = 268K

Since the volume is constant, we can use the following expression:

P1/T1 = P2/T2

35 psi / 309K = P2 / 268K

P2 = 30. psi (2 sig.figs.)