Can a cracked alloy wheel be repaired safely?

How to tell if your wheel is cracked

Cracks are frequently invisible with the tyre on, because they live on the inner rim flange or in the barrel where you cannot see them. The symptoms are more reliable than the eyeball:

• A slow, consistent pressure loss. Two or three PSI a week, every week, from the same wheel. Not the sort of thing a valve does — valves tend to be worse or fine.
• A vibration that survives balancing. Balanced twice, still vibrating? The wheel is either buckled or cracked, and a balancer will not tell you which.
• A recent, memorable impact. If you know exactly which pothole it was, get it looked at even if nothing seems wrong. Cracks propagate.
• A visible line at the flange. Often with a faint dirt trail where air has been escaping through it. That is the obvious one, and it is the minority.

Where a crack can be repaired

The rim flange and the barrel — the parts that hold the tyre and contain the air — are repairable in the great majority of cases. These areas are loaded, but they are loaded in a way that a correctly executed weld handles well, and rim repair is a long-established practice across the industry.

"Correctly executed" is carrying weight in that sentence. A proper repair means:

• The area is cleaned back to bright metal — welding over contamination gives you porosity and a repair that fails.
• The crack is veed out — ground into a V-shaped channel along its length — so the weld penetrates the full thickness of the section rather than bridging the top of it.
• It is TIG welded with a filler matched to the alloy, with heat control that does not distort the rim.
• The weld is machined and dressed back to the original profile so the tyre bead still seats correctly.
• The wheel is pressure-tested before it goes anywhere near a car.

If a repairer cannot describe that sequence to you, ask more questions. A crack that has been filled and painted over is not a repair. It is a decoration on a fault.

Where a crack absolutely cannot be repaired

This is the short, non-negotiable list:

• Through a spoke. Spokes carry the load between the hub and the rim. A welded spoke is a wheel with a known weak point in the exact place you cannot afford one.
• Through or into the hub face or the bolt holes. Same reason, more so.
• Multiple cracks radiating from one point. That is a casting that has failed, not a wheel that has been hit.
• A crack in a wheel that has already been welded there. It failed once.

If someone offers to weld a spoke, that tells you what you need to know about the rest of their work. We will tell you a wheel is scrap and why, and we would rather lose the job than put that on a car.

What about split rims?

Split rims are a separate conversation. Manufacturer guidance on refurbishing them varies enormously, and dismantling and reassembly is the owner's responsibility rather than ours — that is set out in our terms. If you have got them, talk to us before you book rather than after.

The practical answer

Most cracked alloys that come through our door are repairable, because most cracks are flange cracks from potholes. But "most" is not "all", and the only way to know which yours is involves getting the tyre off and looking at it properly. That is a ten-minute job and we would far rather do it than guess down the phone.