At what psi can I travel 65-75mph?
This Maxxis pdf has the same table. Using the table(s) above, my ST175/80R13 with 1060lbs load could run at a minimum 35psi with ~4% reserve capacity. Is there a +10lbs rule? I run with +1...
Forum Discussion
FastEagle wrote:
Tire construction has evolved into a complex science. That science allows tire builders to manufacture tires of the same dimensional size to carry more or less loads according to their internal construction. That’s why the ST235/85R16E can be rated at 3640# at 80 psi and the ST235/85R16F (with larger internal construction materials) can sustain the 95 psi required to carry 3960#. It is also why the ST235/80R16E is rated at 3420# (low end) even though it’s smaller than the LT235/85R16E which is rated at 3042# at 80 psi.
FastEagle
Part of the development process is deciding on the intended purpose. Adjustments are made based on expected usage. I have seen Ultra-Hich Performance "Summer" tires have their tread rubber crack and shatter from being driven on with the temperature well below freezing. If you look you will see that passenger snow tires usually have lower speed rating than passenger summer tires.
