Methodology

Source

https://api.nhtsa.gov/tires?dataSet=ratings returned 7,628 records; we retrieved 7,628 unique records. The API caps pages at 100 rows and only allows non-unique sort keys, so the pull script dedupes by NHTSA record id and checks the total. NHTSA is a U.S. federal agency; works of the U.S. federal government are generally not subject to U.S. copyright. Grade definitions: NHTSA TireWise, 49 CFR 575.104.

What the grades mean

• Treadwear: a number in multiples of 20 relative to a government control tire graded 100. A 200 should wear twice as long as the control on the test course. It is set by the manufacturer and varies in real life with driving, maintenance and climate; it is not a mileage guarantee.
• Traction (AA, A, B, C): straight-ahead wet braking on test asphalt and concrete. Not cornering, not hydroplaning, not dry or snow grip.
• Temperature (A, B, C): resistance to heat build-up on a laboratory wheel.

Cleaning steps

• Brand names differ only by capitalization in places (for example “CONTINENTAL”, “HanKOOK”). Merging case variants reduces 228 raw brand strings to 214 brands and 3,162 product names to 3,023 tire lines. Distinct brands with similar names are not merged.
• 3 records have a missing or zero treadwear and are excluded from treadwear statistics. Out-of-range grades (for example a temperature grade of “500”) are shown as “unverified”. In total 10 records carry a quality flag; the raw values remain in the dataset.
• Sizes are parsed from text such as “P235/75R15” or “255/40R20 101Y” into width/aspect/rim. Only 4,665 of 7,628 records name a specific size; the others read “All sizes”, a rim range, or a speed/series description and are kept at line level only.
• NHTSA's active flag is false on all records and its complaint/recall counts are zero everywhere, so we do not use them. A listed line may be discontinued.

Computed fields

• Median treadwear of a line: median of its records' grades.
• Percentile: share of all lines whose median is strictly lower.
• Brand rank: position among the brand's lines by median treadwear.
• Size rank: lines with a record for that exact size, sorted by the lowest grade filed for that size; ties share a rank.
• Cost per 1,000 miles = price per set ÷ (expected miles ÷ 1,000), from user input only.

Retailer links and maker warranties

• Retailer links on tire-line pages are plain search links to Discount Tire and Amazon, built in one place (src/lib/retailers.ts). We checked on 2026-10-25 that each pattern returns search results. They are marked rel="sponsored nofollow noopener". We have no affiliate relationship today; if we join a program later, affected links will be disclosed on the page. Rankings use only NHTSA grades, never retailer or commission data.
• Maker warranty mileage is shown only where a maker's own public page or flyer states it, with the source URL and the date we read it. Names differ between NHTSA (for example “Defender 2”) and makers (“Defender2”); we match them by hand. A warranty is not a prediction of how long a tire will last.
• We do not scrape prices, so no price is displayed anywhere.

Browse pages: bands, categories, rim sizes

• Treadwear bands (/treadwear/): each rated line is placed by its median treadwear grade across its NHTSA records into 100-point bands (under 200 up to 800 and up).
• Categories (/type/): NHTSA has no tire-type field, so a line is tagged only when its product name contains a marker (A/S, Touring, HP, A/T, H/T and similar). Lines without a marker are untagged, not “not all-season”. Winter tires are outside UTQG, so no winter category exists.
• Rim diameters (/rim/): taken from the parsed size (the number after R). Diameters with fewer than 15 explicit-size records get no page.
• Guides (/guides/): every factual claim links to a page we read (NHTSA, 49 CFR, Tire Industry Association, USTMA, makers). Figures computed from our dataset are labeled; worked examples with invented inputs say so.

Known gaps

• No price feed, and maker warranty mileage only on a handful of lines, so no cost-per-mile ranking yet.
• Size pages list only lines that NHTSA names for that size; a full size catalog feed is needed.
• No vehicle fitment pages yet.

Last updated: 2026-10-25 · Data: NHTSA tire ratings (UTQG) API, pulled 2026-10-25. 7,628 records.