HIGH PERFORMANCE TIRES probably not seem like much to the driver. However, for the tire it will eventually become significant, so exceeding 130 mph on an H-rated performance tire for an extended period of time is not recommended. Likewise, the difference between a 149 mph V-rated tire and a W-rated tire is only 19 mph, but operating a vehicle at 168 mph on tires rated for 149 mph is not safe for the driver and/or other motorists. In North America, the maximum legal speed limit is 85 mph on a 41-mile stretch of toll road in Texas. The western U.S. has a few states with highways that have a speed limit of 80 mph. But the overwhelming majority of the highways and interstates in the U.S., Canada and Mexico have a maximum speed limit of
70 to 75 mph. In that sense, speed rating should not matter. But it does matter in terms of vehicle performance. The U.S. Tire Manufacturers Association (USTMA) and the Tire Industry Association (TIA) both agree that the original equipment (OE) speed rating for the vehicle should, at a minimum, match the speed rating on any replacement tires. On some vehicles, the OE speed rating will be reflected on the placard and in others it will not. Regardless, the standard of care for replacement tires on passenger vehicles is that the OE speed rating must be retained or exceeded when replacing tires. If it isn’t listed on the placard, it’s reasonable to expect the retailer to access the information via the owner’s manual or any number of online
websites and fitment guides. This doesn’t seem like a big deal until it is. The lone exception to downgrading the speed rating is when using winter tires. These tires have lower speed ratings because they are engineered for cold weather conditions and road temperatures, which means they have minimal resistance to heat at high speed. In Europe, drivers have to slow down and adjust their speed if they have winter tires. In North America, drivers with winter tires are more worried about losing control, so speeds rarely approach the maximum speed for the tire and handling is more related to road conditions.
A legal matter
Downgrading a tire’s speed rating in a standard fitment is a layup for any plain-
When installing HP tires and custom wheels, remember the mag seat lug nut has a washer that must spin and a collar that centers in the bolt hole. PHOTO: KEVIN ROHLWING
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Performance Handbook 2023
4/5/23 9:45 AM
2304MT