Originally Posted by
BlazingPedals
It's not just the absolute pressure. The tire size matters. A 2" tire at 100 psi exerts a lot more pressure than a 1" tire at 100 psi. I don't know the exact relationship, but I can tell you that once upon a time I spread a rim by inflating a 2" tire to 90 psi. The stupid part was, there was no need to go that high - at 65 psi the tire was plenty hard.
Actually no. The PSI means the pressure on a surface. 100 psi with a 700x28 tire will exert the same pressure on the rim as 100 psi on a 700x35 tire on that rim: 100 pounds per square inch. Now when the tire or rim blows there's going to be a lot more energy stored in the larger tire.