Wheel Offset Calculator
Enter wheel width, offset, and backspacing to check fitment.
Affiliate links — we may earn a commission at no cost to you. Learn more
Get your results + weekly automotive tips
One email per week. Tips, tool deals, new calculators. Unsubscribe anytime.
Free tools, useful tips. We recommend products we'd actually use.
Understanding Wheel Offset
Wheel offset (ET) determines how far in or out the wheel sits relative to the hub. Positive offset tucks the wheel inward; negative offset pushes it outward.
When changing wheels, compare the new offset to stock. A difference of more than 10-15mm can affect handling, cause rubbing, or put stress on wheel bearings.
Wheel offset is the distance from the wheel's mounting face to its centerline, in millimeters. Positive offset: mounting face is toward the outside of the wheel (most modern FWD and AWD vehicles). Negative offset: mounting face is toward the inside (typical of trucks and off-road vehicles). Zero offset: mounting face is exactly at the wheel centerline.
Changing offset moves the wheel in or out relative to the hub. Decreasing offset by 10mm (e.g., from +45 to +35) moves the wheel 10mm outward. This pushes the tire further out toward the fender — potentially causing rubbing at full steering lock or with suspension compression — while improving the visual stance.
Backspacing = (rim width / 2) + offset (in inches, divided by 25.4). A 9-inch wide wheel with +38mm offset: backspacing = 4.5 + 38/25.4 = 4.5 + 1.496 = 5.996 inches. Backspacing is critical for checking clearance against control arms and brake calipers on the inner side of the wheel.
Safe offset range: most applications tolerate ±10mm from OEM offset without hub bearing wear or handling changes. Going more than 25mm from OEM increases the lever arm on bearings, accelerating wear. Always verify caliper and strut clearance with the actual wheel before purchasing a full set.
See also: Tire Size Calculator · Bolt Pattern Calculator