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
Bionic Man wrote:
What I don't understand is that there is obviously a market for a higher speed rated ST tire without adding the additional 10 PSI. Not sure why someone doesn't step up and fill that void.
Here's what I think:
"Industry standards" are at the root of it all. Those standards have nothing to do with government mandates as some folks believe- they're entirely a result of what the tire industry has worked out among themselves.
It's pretty well understood that the maximum safest speed for trailers is 65. Few if any trailer makers recommend/advise folks to tow faster than that, and NO outfit that rents trailers allows for higher speeds. So the tire industry agrees among themselves that an "ST" tire will only be rated for 65. To put any other speed on the label would be breaking the code or something.
Nobody's going to do that.
But here's what some ARE doing: they're putting out "LT" tires labeled "for trailer use only"...and as "LT's they can be rated at 75! They are in every way a trailer tire, and would be useless if not outright dangerous on steer/drive axles, so they're carefully labeled that they can't be put on a Light Truck or any other motorized vehicle. Aside from the speed rating, they're "ST" tires...but as long as they say "LT" on them no one else in the industry can accuse someone of Breaking the Code.
How ridiculous is that????
