Originally Posted by Donedroolin
Did not know the tires were rated for speeds up o 65. ... Thank you.
Most special trailer tires are speed rated to 65 mph. Speed rated is not speed limited. Tire pressure can affect the speed range. Too little tire pressure is a greater sin than too much pressure. Consult your tire manufacturer information.
Personally I would not run my trailer tires at less than the max rated pressure listed on the sidewall. In my experience that mode gives good wear and puts the tire in a range for higher speeds.
Below is some specific information for
Goodyear Marathon Tires
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.
More info is here:
If the link doesn't work then just add www. to this
What Carlisle says:
Underinflation is the number one cause of trailer tire failure. Low
inflation pressure elevates tread temperature, especially as speed
Review - Practices for Safe Trailer Tire Use
– Maintain air pressure at the maximum PSI recommended on the