CheckFitment

CheckFitment answers one question: will this wheel and tire fit your vehicle? Ask Claude for the bolt pattern of a 2019 Ford F-150 and the connector returns the bolt pattern in millimetres and inches, center bore, thread size, lug nut torque, OEM wheel sizes, offsets and tire sizes, each marked verified (two or more manufacturer sources) or unverified, with the sources listed. A vehicle that is not in the dataset is reported as not found; the connector never guesses. Five calculators use the same maths as checkfitment.com: compare an old and a new wheel (poke, inner clearance, backspacing) with or without tires; compare tire sizes (diameter change and speedometer error); size a wheel spacer and check stud engagement; work out the effective gear ratio after bigger tires and the ratio needed to restore it; and convert a bolt pattern between mm and inches with look-alike patterns that do not interchange. The connector is read-only and needs no account, no login and no API key. It receives only vehicle names and numbers, stores nothing and calls nothing outside the site. It shows no prices, no shop links and no affiliate links; every answer links to the matching free page on checkfitment.com. Results are planning estimates: confirm them against the vehicle's documentation and have fitment checked before you drive. Built and run by CheckFitment (Rainer Lang, Ellwangen, Germany). Not affiliated with any vehicle, wheel or tire maker, OpenAI or Anthropic.