In Russian, the word for “disc” covers two different parts. The wheel is what the tire is mounted on. The brake disc sits behind it on the hub, and the brake pads clamp it. They fail in different ways and are repaired in different ways: a wheel is straightened, a brake disc is resurfaced.
| Wheel | Brake disc | |
|---|---|---|
| Where it is | On the outside; the tire is mounted on it | Behind the wheel; the pads clamp it |
| What goes wrong | Bends from hitting a pothole or curb | Wears and warps from heat when braking |
| Repair | Straightening | Resurfacing (machining) |
| Replace only when | It is cracked | It is thinner than allowed |
Wheel straightening
Signs the wheel is bent
- Vibration at speed appeared after hitting a pothole or curb.
- The tire loses pressure over a few days, with no puncture.
- A dent is visible on the wheel flange.
A tire holds air because its bead seals against the wheel’s bead seat and flange. If they are bent, the seal breaks: the wheel leaks air and vibrates.
Straightening at the shop
The wheel is removed, the tire is taken off and the wheel is inspected. A bent wheel is straightened on a machine, then the wheel is reassembled and balanced. Balancing is needed after any hard pothole impact, even if the wheel did not bend.
The tire is also checked from the inside. After an impact the cord can break inside while the tire looks fine from the outside. A bulge on the sidewall means the tire must be replaced.
When straightening cannot help
Kazakhstan’s rules forbid driving on a cracked wheel. A cracked wheel is replaced.
Brake disc resurfacing
Signs
- The steering wheel or brake pedal shudders when you brake. A common cause is a brake disc warped by overheating.
- Grooves are visible on the disc’s braking surface.
Resurfacing at the shop
The brake disc is machined so its braking surface is flat again. This makes the disc thinner.
When resurfacing cannot help
A brake disc has a minimum thickness, marked on the disc itself as Min. Th., for example on the hub. If resurfacing would leave the disc thinner than that, it is replaced. A tall ridge at the edge of the braking surface also shows the disc has worn thin.
When brake discs are replaced, the pads are replaced too.
Common questions
How do I tell whether the wheel or the brake disc is shaking?
If the steering wheel or pedal shudders only when you brake, a common cause is a warped brake disc. If the steering wheel shakes at speed without braking, usually somewhere between 80 and 120 km/h, have the wheel checked for a bend or lost balance.
Does a wheel need balancing after straightening?
Yes. After straightening the wheel is reassembled and balanced. Balancing is also needed after any hard pothole impact, even if the wheel did not bend.
Where do I find a brake disc's minimum thickness?
On the disc itself, for example on the hub, marked Min. Th. If resurfacing would make the disc thinner than that, it is replaced.
Can I drive on a cracked wheel?
No. Kazakhstan's rules forbid driving with a crack in a wheel disc or rim. A cracked wheel is replaced, not straightened.
Sources
Visual Tire Inspection Before Installation
Michelin
Continental
Michelin
Brembo
Braking a Ford Mustang: the complete guide on when to replace pads and discs
Brembo
Adilet legal database
