Tire Speed Rating Question
I'm posting this here because the speed rating of a tire seems to me to cross all lines/types of vehicles. Reading up on warranty issues/questions just now, I came across the following language ...
Forum Discussion
full_mosey wrote:CapriRacer wrote:
Just an FYI,
There's a provision that isn't well publicized about ST tires (LT tires, too) that you can over-inflate them 10 psi and that allows you to run up to 75 mph. If you also reduce the load by 10%, then you can run up to 85 mph.
So, yes, it is permissible to exceed the inflation pressure written on the sidewall - but only by 10 psi.
Can you do the math for me?
I have a single axle with ST175/80R13 50psi 1360lb rated tires. My heaviest wheel is 1060lbs. I run the psi from 45-50 now.
What pressure would allow me to travel at 65-75mph?
HTH;
John
The correct answer is to use the recommended air pressure value found on the tire placard.
FastEagle
Footnote: If the inflation pressure corresponds to the actual tire load according to the tire manufacturer’s load and pressure table, the tire will be running at 100% of its rated load at that pressure. This practice may not provide sufficient safety margin. Any air pressure loss below the minimum required to carry the load can result in eventual tire failure. (Toyo RV tires)
