When I worked for a coach company for a while they used a product called G101 for everything. They used it for the interiors and exteriors of their vehicles. They just diluted it to suit what they were going to do.

I've used that Auto Glym wheel cleaner, it burns if you get it on your hands.

I don't know what they use at work but, if the mix is too high it makes the windows streaky and is hard to get off.

You say that shop-bought wheel cleaners aren't very effective, but I've always found that Auto Glym Clean Wheels always does the job on my alloy wheels, as long as you use the [fake badger hair shaving] brush as well. Spraying the cleaner on and then hosing it off just gets the loose stuff off. Caked on dirt (possibly a mix of brake dust and mud) takes a bit of effort with the brush after leaving the spray to do its work for 30 seconds or so, but it does come off.

Then rinse with the hose on low and keep brushing until all the cleaner-muck combination has gone, and ta-da! IMO anything that only needs just a pressure washer to lift off the grime is very corrosive and in the longer term surely must start to damage the wheels' surface themselves - ok for a lorry where you might not be so worried about appearance, but on a car, hmmm.

All the stuff requires is to be sprayed on neat and left for about as long as it takes to drag the pressure washer out and fire it up-it hasn't corroded my current vehicle wheels in 7 years or motorcycles wheels discs or calipers in a longer time- as long as it washed off with a hose on a moto,

Bear in mind this isn't that company's full-strength cleaner, they do a super strength one as well.

Auto-Glym stuff is brilliant but a bit expensive for cleaning wheels with.