What is the bolt pattern (PCD)?

The bolt pattern, or PCD, describes the number of mounting bolts and the diameter of the circle they sit on. For example, 5x112 means five bolts on a 112 mm circle. The rim’s pattern must match the car’s hub exactly: even a couple of millimetres of difference means the bolts cannot be tightened correctly and the wheel will not seat safely. You can find your car’s pattern in the owner’s manual or via a wheel retailer’s fitment search.

What does a wheel’s ET mean, and what happens if it is wrong?

ET, the offset, is the distance in millimetres between the wheel’s mounting face and its centreline. It determines how deep the wheel sits under the arch. An ET different from factory changes the track: a lower ET pushes the wheel outwards, where it can rub the arch, and a higher ET moves it inwards, where it can touch suspension parts. Larger deviations also add load on the wheel bearings. Stay close to the factory value.

What is the centre bore, and are hub-centric rings safe?

The centre bore, or CB, is the diameter in millimetres of the hole at the centre of the rim, which centres the wheel on the car’s hub. If the rim’s bore is larger than the hub, a plastic or aluminium hub-centric ring fills the gap — a normal, safe and widely used solution. The opposite case has no remedy: a rim with a bore smaller than the hub simply will not fit. Adaptation only ever works downwards.

Steel or alloy wheels for winter?

For a winter set, steel wheels are the practical choice: they cost less and cope better with potholes and kerbs — on impact a steel wheel tends to bend, while an alloy can crack. Road salt also attacks an ordinary alloy faster. If looks matter to you in winter, choose alloys specifically approved for winter use, which carry a salt-resistant coating. For a summer set, an alloy’s lightness and appearance make it an easy pick.

How to choose rims: bolt pattern, ET offset and centre bore explained

A rim must match your car in three measurements: bolt pattern, ET offset and centre bore. If any one of them is wrong, the wheel cannot be fitted safely, no matter how good it otherwise is. Here is what each figure means, plus the logic of choosing between steel and alloy.

Three measurements that must match

The bolt pattern, or PCD, gives the number of bolts and the diameter of the circle they sit on. For example, 5x112 means five bolts on a 112 mm circle. The pattern must match exactly — a 5x112 rim cannot be mounted on a 5x114.3 hub.

ET, the offset, is the distance in millimetres between the wheel’s mounting face and its centreline. A wrong ET changes the car’s track: too low an ET pushes the wheel outwards where it can rub the arch, too high an ET moves it inwards where it can touch the suspension. Stay close to the factory ET.

The centre bore, or CB, is the diameter in millimetres of the hole in the middle of the rim, which must fit the car’s hub. If the rim’s bore is larger than the hub, the gap can be filled with a hub-centric ring. The reverse has no fix: a rim with a bore smaller than the hub cannot be fitted at all.

Steel or alloy

Steel wheels are cheaper and tougher against impacts — hitting a pothole tends to bend them rather than crack them. That makes them a popular choice for a winter set, where road salt and potholes take their toll.

Alloy wheels are lighter and better-looking, and the lower unsprung mass slightly improves ride and handling. An ordinary alloy can suffer from winter road salt, but some alloys are approved for winter use and carry a salt-resistant coating. If you want alloys year-round, look specifically for those. You can browse suitable wheels in our range at /rims.

Frequently asked questions

What is the bolt pattern (PCD)?: The bolt pattern, or PCD, describes the number of mounting bolts and the diameter of the circle they sit on. For example, 5x112 means five bolts on a 112 mm circle. The rim’s pattern must match the car’s hub exactly: even a couple of millimetres of difference means the bolts cannot be tightened correctly and the wheel will not seat safely. You can find your car’s pattern in the owner’s manual or via a wheel retailer’s fitment search.
What does a wheel’s ET mean, and what happens if it is wrong?: ET, the offset, is the distance in millimetres between the wheel’s mounting face and its centreline. It determines how deep the wheel sits under the arch. An ET different from factory changes the track: a lower ET pushes the wheel outwards, where it can rub the arch, and a higher ET moves it inwards, where it can touch suspension parts. Larger deviations also add load on the wheel bearings. Stay close to the factory value.
What is the centre bore, and are hub-centric rings safe?: The centre bore, or CB, is the diameter in millimetres of the hole at the centre of the rim, which centres the wheel on the car’s hub. If the rim’s bore is larger than the hub, a plastic or aluminium hub-centric ring fills the gap — a normal, safe and widely used solution. The opposite case has no remedy: a rim with a bore smaller than the hub simply will not fit. Adaptation only ever works downwards.
Steel or alloy wheels for winter?: For a winter set, steel wheels are the practical choice: they cost less and cope better with potholes and kerbs — on impact a steel wheel tends to bend, while an alloy can crack. Road salt also attacks an ordinary alloy faster. If looks matter to you in winter, choose alloys specifically approved for winter use, which carry a salt-resistant coating. For a summer set, an alloy’s lightness and appearance make it an easy pick.