I seem to have had a life long battle trying to keep wheels clean of brake dust
I've tried about every wax and sealant out there with limited success. Performance brake pads in general produce more brake dust of the tyre that is harder to remove, with lots of iron content that normal soap and water won't shift.
tl;dr - if you use your brakes a lot, there's not much you can do to prevent brake dust and you just have to get used to cleaning wheels!
Back in the 90s, Halfords sold black rubber discs with a thin metal fitting plate in the centre that fitted between the hub and the wheel, giving a good seal and preventing dust getting onto the face of the wheels. Sounded good in theory and I bought a set and ran them for about a year. After a while the wheels got more and more out of balance for some reason. Fine below about 50-60mph, but above that and you got horrible vibrations. I also thought they allowed the brakes to get too hot under extended use, and it annoyed me not being able to see how much brake pad material was left, so I ditched them.
I then discovered Wonder Wheels, which was great at cleaning all sorts of brake dust effortlessly. This is an acidic cleaner that stings like hell if you have cuts in your hands. I loved this stuff until I ruined a set of wheels with it by leaving it on far too long on the wheels which had a few stone chips and minor scratches. The wheels hadn't been washed in months after several track days and some heavy road usage. A few months later large areas of lacquer and paint had come off the face of the wheels as the acid cleaner had worked it's way underneath allowing the salt from the (now winter) roads to attack the meatl.
I then tried various waxes, polishes and sealants. Most of these had little or no effect, but perhaps made the cleaning slightly easier if the brake dust was only light. Under heavy braking though, the brake dust particles get very hot and just seem to melt through any wax and stick to the wheel surface anyway. End result is that 99% of the brake dust washes off easier, but you are still left with those annoying raised spots of brake dust in the corners of the spokes.
One of the best cleaners 15-20 years ago was Dr Wack P21-S, which you could safely leave to dwell on the wheels for hours if you wanted, and then just jet wash off. It was quite expensive though (about £20/litre) and not readily available in the UK.
Then came the range of iron-cut wheel cleaners, which work in a similar way but much better for stubborn dust. The first products smelled really bad of rotten eggs, but worked like magic, dissolving those nasty iron spots of brake dust into a purple liquid that rinsed off easily. There are now lot of these products on the market, and they generally smell a lot better and work better also. My current choice is the Autosmart Red-7 product which you can buy in 5 litre containers. As good as it is, there are still some dust and stains that it doesn't remove, particularly if you have left the wheels many months, and a more aggressive cleaner may be needed. There are many "non acidic" wheels cleaners on the market, but most of these are alkaline. These work well enough, but you can't leave them to dwell on the wheels too long, or dry in. I'm currently using a product called Autosmart Smart Wheels for this, again available in a 5L size
. Generally I'll jet wash my car, spray on the red 7 stuff on the wheels and leave it to work whilst washing the rest of the car, then rinse if off along with the soap using the power washer. Every few months, I'll then give the (still wet) wheels a spray with the Smart Wheels, agitate with a brush and then rinse off after a few minutes at most.
A couple of years ago I tried ceramic coating the wheels. Took the wheels off and spent a day cleaning and polishing them by hand and applying the ceramic sealant (Auto Finesse). Initial impressions were good, and the wheels would come out like new after just a pressure wash, but over time as more debris (tar spots) and stubborn brake dust attached itself to the wheels, they would need a good clean. I refreshed using the red 7 and smart wheels which took off the worst of this, and they were back to the way they were, with the water and most of the dust just beading off with the presure washer. After 2 years though, the coating had effectively stopped working or had been worn off through washing. Faced with the choice of spending a day cleaning them and re-applying a ceramic sealant again, I opted for the easy option and reverted to my previous cleaning regime. When I swap onto my winter wheels and tyres in about November, I'll most likely spend the time cleaning them and apply another ceramic sealant at that point, as it really did make a noticable difference over many months.
