The short answer
A dedicated non-acidic wheel cleaner, a soft brush, and do them when the wheels are cool. Acidic cleaners strip the lacquer and the damage does not show for months.
- Do the wheels when cool, never straight after a drive. Hot metal makes cleaner dry instantly and etch.
- Rinse first, then apply a pH-neutral wheel cleaner.
- Let it dwell for the stated time and use a soft brush in the spokes.
- Rinse thoroughly, including behind the spokes.
- Use separate brushes and buckets from the paintwork, always.
What will ruin it
Strongly acidic wheel cleaners, and household limescale removers used as a substitute, attack the lacquer on alloy wheels. The result is a dull, pitted, milky finish that cannot be cleaned off and needs the wheel refurbishing.
Why it works
Brake dust is hot iron particles that embed into the lacquer. Acid dissolves them fast, which is why the aggressive products work so well and why they take the lacquer with them.
Household chemicals can be dangerous in combination. Never mix them, keep the room ventilated, and test anything on a hidden patch first. Full disclaimer.