The treadwear grade is expressed as which type of number?

The treadwear grade is indeed expressed as a three-digit number. This grading system is part of the Uniform Tire Quality Grades (UTQG) established by the National Highway Traffic Safety Administration (NHTSA) to help consumers make informed choices about tires. The treadwear grade specifically indicates the durability of a tire's tread, with higher numbers reflecting a longer expected lifespan under standardized testing conditions. For example, a tire with a treadwear grade of 400 is expected to last twice as long as a tire rated at 200, assuming similar driving conditions.

This three-digit format helps convey a clear comparison between different tire models, allowing consumers to choose tires based on their longevity and performance expectations. Other formats, like single-digit numbers or percentages, do not effectively communicate the comparative durability established by the treadwear grading system.