Wheel fitment guide

A wheel fits when five measurements are right. Two of them decide whether it bolts on at all; the other three decide whether it clears the things around it once it does. Getting the first two right and the last three wrong is the common expensive mistake, because the wheel mounts, sits there looking correct, and then rubs on the first turn.

1. Bolt pattern — will it bolt on

Written as lug count × circle diameter: 5x114.3 is five studs on a circle 114.3mm across. The circle is measured stud centre to stud centre for even lug counts, and centre-to-the-far-side for odd ones, which is why a five-lug pattern is awkward to measure with a tape.

The confusion here is notation, not engineering. The same circle gets written in millimetres or inches depending on who is speaking: 5x114.3 and 5x4.5 are one pattern. Meanwhile 5x114.3 and 5x115 are genuinely different, and 0.7mm apart.

2. Hub bore — will it centre

The hole in the middle. On most vehicles the wheel is hub-centric: it locates on a machined lip on the hub, and the studs only clamp it. The bore must therefore be at least as large as the hub, and ideally the same.

Aftermarket wheels are usually bored oversize to fit many vehicles, and are centred with plastic or alloy hub rings. That is normal and fine. A wheel whose bore is smaller than the hub is not fixable — it will not sit flat.

Skip the rings and the wheel is centred only by the taper of the lug nuts, which is good enough to drive on and not good enough to be smooth. Most "the new wheels vibrate" complaints are a missing set of hub rings rather than a balance problem.

3. Offset — where the wheel sits in the arch

Offset is the distance from the wheel's mounting face to its centreline, in millimetres, written ET or +35.

• Positive offset puts the mounting face toward the street side, pulling the wheel inboard, toward the suspension. Standard on front-wheel-drive cars.
• Negative offset pushes the wheel outboard, toward the fender. The deep-dish look, and standard on trucks.
• Zero is the mounting face exactly on the centreline.

Lower the offset number and the wheel moves out. Raise it and the wheel moves in. Each direction runs out of room somewhere: outboard you hit the fender lip, inboard you hit the strut or the control arm. Ten millimetres either way is usually absorbed; thirty usually is not.

4. Backspacing — the same idea, measured differently

Backspacing is the distance from the mounting face to the inboard lip, in inches. It describes the same geometry as offset, from the other end, and truck people tend to use it while car people use offset.

The practical difference is that backspacing already includes the wheel's width, so two wheels with the same backspacing and different widths sit differently. Offset is the more portable number.

5. Width — what the tire needs

Every tire size has a range of rim widths it is designed to mount on, typically about two inches wide. Inside that range the tire takes its intended shape. Outside it the sidewall is pulled or pinched: too narrow a wheel rounds the tread crown and reduces the contact patch, too wide a wheel stretches the tire and exposes the rim.

Reading a full fitment

A complete specification looks like 20x9 5x114.3 +35 66.1 — twenty inches by nine wide, five lugs on 114.3mm, offset +35, hub bore 66.1mm. Five numbers, in that order, every time.

Every wheel on this site is listed with all five, and filtering by your vehicle checks all of them against what that chassis actually takes — including clearance, which is the part no calculator can work out from dimensions alone.