WARNING
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 P235/65R18, P235/55R20, or 235/55R20 size tires require inflation pressure adjustment when driving the vehicle at speeds of 160 km/h (100 mph) or higher. Set the cold inflation pressure to the maximum inflation pressure shown on the tire sidewall, or 260 kPa (38 psi), whichever is lower. Return the tires to the recommended cold tire inflation pressure when high-speed driving has ended. See Vehicle Load Limits and Tire Pressure.

The maximum load and inflation pressure is molded on the tire sidewall, in small letters, near the rim flange. It will read something like this: Maximum load 690 kg (1521 lbs) 300 kPa (44 psi) Max. Press.