Diamond-cut wheel repair.

Diamond-cut wheels cannot be repaired with paint. The fine concentric grain on the face comes off a lathe, and the only way to restore it is to put the wheel back on one.

How to tell if you have them

Look at the face of the wheel in direct light. If you can see very fine concentric rings, like the grooves on a record, that is a machined or diamond-cut face. The bright areas are bare cut aluminium under a thin lacquer; the recessed areas are usually painted.

Common on BMW, Mercedes-Benz, Audi, Range Rover, Lexus and many Tesla wheels — see Tesla wheel repair.

Why they fail the way they do

The lacquer over a machined face is thin, and bare aluminium sits directly beneath it. Once a kerb, a stone chip or an aggressive wheel cleaner breaks that layer, moisture gets underneath and the face corrodes — showing as a white milky bloom spreading out under the clear coat. It does not stop on its own, and every month of delay means more material has to come off in the repair.

The repair

1. Strip the lacquer and assess how deep the corrosion has gone.
2. Repair kerb damage and check for runout — see wheel straightening.
3. Re-cut on the lathe. The face is mounted true and a fine layer machined off, restoring the concentric grain across the whole face so it matches edge to edge.
4. Repaint recesses where the design is two-tone.
5. Re-lacquer and cure.

Beware anyone offering to "match" a diamond-cut face with paint or a silver aerosol. It reads as a repair from three metres away, in any light.

How many times can a wheel be re-cut?

Not unlimited. Each cut removes material, so there is a finite number of times before the face becomes too thin to be safe — typically a small handful over a wheel's life, depending on how much was taken each time. We measure and tell you honestly where a wheel stands. If it has been cut too often already, we will say so rather than take one more pass and hand you back something we would not run ourselves.

Common questions