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
full_mosey wrote:
dspencer;
The whoosh refers to the missing of the actual topic, that is, where is this +10psi rule that allows an ST tire to travel up to 75mph.
RinconVTR wrote:
Did I miss something? The question was is there a +10psi rule? I don't know of one myself, and I don't see any posts that confirm there is.
By George...I think I've found something!
Here's a direct quote from a 2011 Goodyear Tire Bulletin
Goodyear wrote:
Special Trailer (“ST”) Tires
Goodyear Marathon trailer tires are widely used in a variety of towable trailer applications and are designed and branded as “ST” (Special Trailer) tires.
• Industry standards dictate that tires with the ST designation are speed rated at 65 MPH (104 km/h) under normal inflation and load conditions.
• Based on these industry standards, if tires with the ST designation are used at speeds between 66 and 75 mph (106 km/h and 121 km/h), it is necessary to increase the cold inflation pressure by 10 psi (69 kPa) above the recommended pressure for the rated maximum load.
o Increasing the inflation pressure by 10 psi (69 kPa) does not provide any additional load carrying capacity.
o Do not exceed the maximum pressure for the wheel.
o If the maximum pressure for the wheel prohibits the increase of air pressure, then the maximum speed must be restricted to 65 mph (104 km/h).
o The cold inflation pressure must not exceed 10 psi (69 kPa) beyond the inflation specified
for the maximum load of the tire.
