Guide
Wheel fitment specs: bolt pattern, offset, hub bore
Year/make/model is the start. Bolt pattern, offset (ET) and center bore decide whether a wheel actually mounts without spacers, rubbing or vibration.
Wheel fitment is the set of measurements that determine whether a wheel mounts on a vehicle safely: bolt pattern, offset, center bore, and width/diameter relative to fender clearance.
Bolt pattern
Bolt pattern is the number of lug holes and the diameter of the circle they sit on, written like 6x135 or 5x114.3. If this does not match the hub, the wheel does not bolt on.
Offset
Offset (ET) is the distance in millimeters from the wheel’s centerline to the mounting face. Positive offset tucks the wheel in; negative offset pushes it out. Wrong offset causes rubbing or inner-liner contact even when the bolt pattern is correct.
Center bore (hub bore)
Center bore is the hole that centers the wheel on the hub. Hub-centric fitment matches this diameter (for example 87.1 mm on many F-150 applications). A larger bore can run with a hub-centric ring; a smaller bore will not seat.
Why this belongs on Shopify, not in a PDF
Shoppers on phones will not decode a spec sheet. A YMM selector that hides non-fitting SKUs cuts “does this fit?” tickets and wrong-fit returns. The same structured specs are what AI assistants read.
Written by Jack Nalbandian, Momentum Fitment. Momentum Fitment is the fitment and AI visibility platform for Shopify wheel and tire stores.