Wheel Offset ↔ Backspacing Calculator
Two ways of saying the same thing — where the hub face sits in the wheel. Type either number and watch the diagram move.
Bead-seat width, e.g. the 6 in 15X6
Edit either one — the other updates.
Positive offset = hub face toward the street side (wheel tucks in). Negative = face toward the brakes (wheel pokes out, deep dish).
Picking wheels? We'll match the fitment.
Give us bolt pattern, width and offset or backspacing — we'll quote steel and custom wheels from stock.
Common questions
What's the difference between offset and backspacing?
Both describe where the wheel's mounting face sits. Offset is measured from the wheel's centerline in millimeters (positive = toward the street side). Backspacing is measured from the back flange to the mounting face in inches. Same information, two conventions — trailer and off-road catalogs love backspacing, import and passenger catalogs love offset.
How do I convert offset to backspacing?
Backspacing = (wheel width + 1) ÷ 2 + offset ÷ 25.4. The +1 inch accounts for the flanges on each side of the bead width. Example: an 8-inch-wide wheel with 0 offset has 4.5 inches of backspacing.
What offset do trailer wheels use?
Almost all standard trailer wheels are zero offset — the mounting face sits on the centerline, so backspacing is simply half the overall width. That keeps the load centered over the bearings.
Will a different offset rub?
More negative offset pushes the wheel outward (fender side); more positive pulls it inward (suspension and caliper side). Staying within about ±5 mm of stock is generally safe; beyond that, check caliper, suspension and fender clearance — and remember bearing loads grow as the wheel moves outboard.