GMC Sierra Owners Manual
Tire Pressure for High-Speed Operation
Driving at high speeds, 160 km/h (100 mph) or higher, puts an additional strain on tires.
Sustained high-speed driving causes excessive heat buildup and can cause sudden tire failure.
You could have a crash and you or others could be killed. Some high-speed rated tires require inflation pressure adjustment for high-speed operation. When speed limits and road conditions are such that a vehicle can be driven at high speeds, make sure the tires are rated for high-speed operation, in excellent condition, and set to the correct cold tire inflation pressure for the vehicle load.
Vehicles with P265/70R17 or P275/ 55R20 size tires require inflation pressure adjustment when driving the vehicle at speeds of 160 km/h (100 mph) or higher. Set the cold tire inflation pressure to 20 kPa (3 psi) above the recommended cold tire pressure shown on the Tire and Loading Information label.
Return the tires to the recommended cold tire inflation pressure when high-speed driving has ended. See Vehicle Load Limits on page 9‑17 and Tire Pressure on page 10‑62.