Where can you have wheels repaired?

“Especially with damage that goes beyond a small scratch on the wheel, a specialist should urgently be consulted, because only a specialist can judge whether a safe repair is still possible at all. Professional wheel repair businesses also have the technology to check badly damaged wheels for cracks and deformation, for example by 3D laser measurement, X-ray or eddy-current testing. In case of doubt the defective wheel should always be replaced with a new one.”

Dipl.-Kfm. Thomas Beez, wheel expert and managing director of Mainhattan-Wheels GmbH

Since the very beginning of our wheel repair activity, the most frequent question on the phone has been: “Do you repair wheels too?” We often hear from customers that it is not at all easy to find a competent contact, and how glad they are to have finally found one. That honours us on the one hand; on the other hand it gives us pause.

Almost daily we receive enquiries preceded by a bad experience with a wheel repair. When we inspect the wheels concerned, we often find that the work was done unprofessionally. The range is wide, from the wrong colour shade to a wheel cracked in several places that was nonetheless welded. Where an unsightly surface after a repair is “only” annoying, welded cracks are no laughing matter. Here it is negligently accepted that the wheel will not withstand the loads of road traffic in the long term and that personal injury may even result.

Especially with damage that goes beyond a small scratch, a specialist should be consulted, because only a specialist can judge whether a safe repair is still possible at all. Professional businesses also have the technology to check badly damaged wheels for cracks and deformation, for example by 3D laser measurement, X-ray or eddy-current testing.

Two categories of wheel damage

In principle wheel damage falls into two categories:

1. Superficial damage with material loss of up to 0.5 mm.
2. Structural damage where the wheel is cracked or deformed or shows heavy material loss (over 0.5 mm).

Superficial damage: what to look for when choosing a workshop

With superficial damage up to 0.5 mm there is normally no danger from the damage itself. When choosing a suitable wheel repairer, make sure it actually offers the required processes. To restore almost all surfaces true to the original, wet painting, powder coating and CNC diamond cutting belong to the standard repertoire of a specialist wheel repair business. Otherwise the available processes are used to imitate the result of the missing ones, which usually leads to an inferior result. Even if all processes are offered, we recommend asking specifically how the work is carried out. Examples:

• Many original paints are effect paints that usually cannot simply be reproduced 1:1. Ask about a possible colour deviation.
• With painting, spot repair or smart repair is often offered. Ask whether the whole wheel is sealed with clear coat after the partial work. Otherwise there are often durability problems.
• CNC diamond cutting is often advertised while in fact a manual rotary grinding process is used. The result has little in common with CNC machining.
• If a diamond-cut wheel is CNC-machined, always ask whether the business is able to remove material only in the damaged area and merely over-turn the clear coat on the rest of the wheel, or whether material is removed evenly across the whole face. Between the two variants can lie important millimetres that help ensure the wheel is not weakened by the repair. Non-uniform over-turning is always preferable. That is how we work in CNC diamond cutting.
• Make sure the business carries out all work in the course of the wheel repair itself. If work is outsourced, this can affect price and turnaround time.

Structural damage: this is about your safety

With structural damage the choice of a suitable business is even more important. A specialist must judge whether the wheel can be repaired without a risk of fractures or cracks afterwards. Examples:

• The wheel is deformed.
• The wheel shows damage reaching deep into the material.
• The wheel has one or more cracks.

There are no guidelines for wheel repair, but there is a position of the Federal Ministry of Transport on returning repaired wheels to public road traffic. The special committee “Wheels and Tyres” of the Motor Vehicle Technology Committee (FKT) states in an opinion “… that a repair of damaged light-alloy wheels is fundamentally to be rejected. Repair means any intervention in the material structure, heat treatment and re-forming. …”

With deformed wheels one must assume that even a structure-preserving repair weakens the wheel. If at all, only minimal deformations can be corrected, depending on where the deformation is and what material the wheel is made of.

With damage reaching deep into the material, it must be decided case by case whether a safe repair can be guaranteed. Besides the damage itself, the manufacturing process and the material used should be taken into account.

In our experience cracks should never be repaired. Firstly, the wheel has already suffered considerable structural damage through the formation of the crack, which can lead to cracks forming elsewhere after welding. Secondly, welding introduces an enormously high temperature; this changes the aluminium structure, which can make the alloy brittle and crack as well.

In case of doubt the defective wheel should always be replaced with a new one.