Aluminum doesn’t rust, but there could be other reasons why rust is on the wheel. Rust on aluminum rims could be from a worn caliper piston, seized caliper pins, rusty brake pads, or a rusted brake rotor. This article and video reviews why you might find rust on an aluminum wheel and how to get rust off an aluminum rim.
Why Is Rust on My Aluminum Rims?
If you have a rusted wheel it may not actually be rusted. While parts made of steel, like a steel wheel, can rust, especially if left exposed to outside elements like rain for long periods of time, parts made of aluminum can’t rust. This means if you have a rusted aluminum wheel, you might just have to clean it to fix it.
You might wonder why a part like an aluminum wheel would have a rusted discoloration. Rust can get there if parts in the brake system are rusted and broken.
How Do I Know If My Wheel Is Made of Aluminum?
You can tell if you have an aluminum or steel wheel by putting a magnet onto it. The magnet won’t stick to an aluminum wheel.
How to Inspect Brake Parts for Rust and Wear
Check for Rusty Rotors and Brake Pads
Behind wheel there will typically be a steel rotor or brake drum. Since steel rusts, moisture that collects on exposed areas can corrode the rotor over time.
Brake pads or brake shoes will have different types of materials, such as ceramic, semi-metallic material, or metallic material. Metallic pads have types of metal inside, they last a little longer, may be a little noisy, and the brake dust will have a lot of metal.
Manufacturers designed brake pads to move around inside the caliper bracket freely. If a pad is stuck, it can grind away as the rotor spins, and this causes constant friction that will wear the pad away and create an opportunity for material to collect on the rim.
If you like to wait on replacing your brakes, for example still driving when they are worn down and squealing from the warning indicator, that can cause dust as the scraped metal particles accumulate on wheel.
Steel with moisture on it will rust, and the pads that have metal flakes that can rust also. A sign that the brakes are rusted is, after the vehicle has been sitting for some time, hearing a grinding noise when first stepping on the brakes. This is also more likely to happen if it’s humid.
Broken Brake Caliper Piston
Brake fluid forces the caliper piston out. It presses on the pads, which press to the rotor and allow the car to come to a stop. The piston can seize up. If the brake caliper piston boot rots or breaks, moisture can get inside, cause rust, and seize up the piston.
You test the brake caliper piston to check its condition. A seized caliper piston will not go into the caliper despite the assistance of tools like a C-clamp. A working caliper piston will contract and expand easily.
Seized Brake Caliper Slide Pins
The slide pins move every time the caliper is squeezing and releasing. If the slide pins are frozen, the caliper won’t release. If the pads are stuck on the rotor, it causes excessive friction and more heat. This pad material can spray out inside the wheel and wheel well, like on an aluminum rim.
Scraping Brake Pad Brackets or Backing Plate
The brake pad brackets and the backing plate can cause an issue by scraping against the rotor. These two will create a loud squealing noise and may kick up rust and dust.
How to Clean a Rusted Aluminum Wheel
There’s a big difference between leaving a little bit of dust like after a drive or leaving metal particles on the wheel for an extended period of time. To get rust off an aluminum rim, you might try using household items or other automotive cleaners like glass cleaner, degreaser, rust penetrant, or disinfectant wipes. We tried some of these methods, and some can clean some rust off, while others were not so effective.
How to get rust off aluminum rims
- Do not clean a rusty aluminum rim with a brush, grinder, or water
Spraying and cleaning a rusted aluminum wheel with water will not effectively remove the rust.
A brush and grinder is a common way to get rust off of automotive bodies, but it can scuff up and scratch an aluminum rim’s coating, and a grinder will wear away the wheel. - Glass cleaner, rust penetrant, degreaser, or disinfectant wipes may clean a rusted aluminum wheel
Glass cleaner, rust penetrant, degreaser, or disinfectant wipes and a rag may clean parts of the wheel like the outside of the rim, but it might not be effective at removing rust from other areas. These may work if you want to get some of the rust off and don’t mind if the wheels aren’t looking brand new.
- Sand and smooth the rust off from the aluminum wheel
The ideal way to get rust off aluminum rims is to remove the tire from the wheel. Sand it down to smooth it, and then recoat it with a protectant.
- Leave the rust on the wheel
If you find rust on your aluminum rims, you don’t really need to remove the rust if you don’t mind the appearance. The rust won’t corrode the wheel any further, so there isn’t much of a concern if you aren’t worried about your car looking brand new. However, it may be a sign another part is worn or wearing, like the brakes.
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