treadwear

Treadwear is a standardized rating that predicts tire lifespan under controlled test conditions. The number itself is a ratio: a tire rated 400 will theoretically last four times longer than the reference tire, which is assigned 100. The higher the number, the more miles you should expect before the tread wears down to 2/32 inch depth, the legal minimum for safe grip on wet roads in most jurisdictions.

The rating comes from the Uniform Tire Quality Grade (UTQG) system, which is printed on the tire sidewall alongside ratings for traction and temperature resistance. To establish a treadwear number, manufacturers run tires on a 400-mile test course in Arizona that includes different road surfaces and wear patterns. The actual wear rate is then indexed against a standard reference tire tested under identical conditions, producing the numerical grade. A typical all-season passenger tire might rate 400 to 600; budget tires often 200 to 300; premium or touring tires sometimes 800 or higher.

Real-world complexity

The UTQG treadwear rating is useful but not predictive for your specific driving. Actual wear depends heavily on alignment, inflation pressure, driving style, climate, road surface, and load. A tire rated 400 might last 30,000 miles on poorly aligned wheels or 60,000 on well-maintained ones. Highway driving extends tire life compared to stop-and-go city use. Hot climates accelerate rubber degradation. The test course itself, though standardized, cannot replicate every driver's experience.

Manufacturers have incentive to be conservative with their ratings: an overstated claim invites warranty claims and reputation damage. However, the UTQG test is manufacturer-conducted and not independently verified, so comparison between brands requires skepticism. A competitor's 500-rated tire may or may not outlast a 400-rated tire from another maker, depending on rubber compound, construction, and design priorities.

The treadwear number should not be your only purchase criterion. A softer, lower-rated tire may grip better in rain or cold; a higher-rated tire often sacrifices wet traction for longevity. Premium all-season tires often sit in the 500 to 700 range. Winter tires typically rate lower, sometimes 200 to 400, because their rubber compound prioritizes flexibility in cold over durability. Performance tires trade life for handling and may rate 200 to 400 as well.