Lately, the front wheels of my '23 GLS450 has been covered in some brownish/copper-colored grime. I initially thought it was mud due to all the rain we've had but then the back wheels should have had it too.

Is this brake dust?

 

The brake dust on all four of our MB's is black. They all have standard brake pads, not ceramic. I can say that the fronts emit what seems like ten times the amount of the dust as the rears.

 

What color is ceramic brake dust?

 

It's probably just brake dust mixed with some flash rust off of the rotor surface that forms overnight when they get wet or in high humidity settings. You said its been raining a lot. All rotors will do that, and the fact that it's on all 4 wheels at the same time, makes me believe that's what it is. Very small chance you have a problem like that on all 4 wheels at the exact same time if it weren't a natural occurrence. Ours does it too on all of our cars. My w212 has silver wheels, and you can really see it on them. One of the things I like to do when I spend the time to detail our cars is to clay the inside of the rim, spray some of that stuff that dissolves the iron deposits, and then when clean and dry, put a decent amount of the ceramic protection on them. Doesn't make the dust just magically fly off, but helps to make it a lot easier to clean up and helps to prevent elements from sticking/bonding to the rim.

 

Brake dust.

 

Yup if it is the rust you are talking about, that's fallout. Fallout Remover should do the trick.

To OP: As for why the front wheels are more covered, as someone mentioned already it gets way more dust, that is because the front brakes are bigger and have more stopping power than the rear anyways. That said, modern MBs usually use the rear brake first and then when you floor the brakes or if another situations calls for it, it will use both brakes. DISTRONIC for example likes to use the rear brakes more than front and so is lane keep etc.

 

Same. My front wheels get WAY dirtier than my rears. Most of the braking happens in the front.

 

Thanks, everyone!

 

Brake dust, it has a black/brownish color. MB OEM Brakes make TONS of dust. Switching to ceramic pads is one of the best things I have done for the car. Otherwise it needed to be washed at least 2 times a week to stay looking clean

 

What brand of brake pads did you install and do you have any squeaking? My fronts are so brownish after every wash and its really bothering me. I've never had a car that gets so much brake dust before.

 

Mine are a small manufacturer who does not sell direct to consumers. They were sourced by my independent mechanic. If I were buying retail I would buy Powerstop Z23 pads.

Seriously though, I enjoy the car SO much more with the ceramic pads. It looking dirty all the time really diminished my enjoyment of it