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The Maxxis M8008 ST Radial is "Q" speed rated. However, according to the Tire and Rim Association, the U.S. tire industry specification authority, inflation pressures and load specifications in general for any ST Radial trailer tires, without a service description, regardless of the manufacturer, are designed and rated at 65 MPH. If the speed is higher than 65 MPH, the pressure and load need to be adjusted according to the following guidelines:
From 66 to 75 MPH – the tire inflation pressure needs to increase 10 PSI (not to exceed the maximum PSI the tire is rated for) but requires no load adjustment.
From 76 to 85 MPH – the tire inflation pressure needs to increase 10 PSI (not to exceed the maximum PSI the tire is rated for) and load should be reduced by 10%.
We hope this information is helpful. Thanks for your inquiry and interest in Maxxis Tires.
Your Maxxis Support Team
Maxxis International – USA
| Web: maxxis.com