Wheels

This section covers the wheels and the hardware that holds them on: alloy wheels by diameter, wheel spacers and adapters, wheel bolts, locking bolts and nuts, and wheel studs.

A wheel is described by five figures, all given in the listings:

• diameter;
• width, in J;
• bolt pattern or PCD, such as 5×112 or 5×120;
• offset (ET);
• centre bore.

The PCD has to match the hub exactly. Width and offset together decide where the tyre sits in the arch, so changing either can bring the tyre closer to the suspension or the wing. A wheel with a larger centre bore than the hub is centred with a spigot ring. Where a load rating is listed, it should be at least half the maximum permitted load on the car’s heavier axle.

New wheels usually bring other changes. The bolts or nuts must suit the wheel’s seat, whether conical or ball, and be long enough for the wheel and any spacer. A larger diameter needs a lower-profile tyre to keep the overall rolling diameter, and big brake calipers need enough clearance inside the spokes. Cars with tyre pressure sensors need the sensors moved across or new ones fitted.

Torque the fixings to the car maker’s figure in a star pattern, and check them again after the first few miles.