I snowfoam with close to pH neutral homemade foam.
Soak for 10mins. Bucket wash with warm water and lambswool mitt.
Dry off with a brand new microfibre every time.
Never powerwash them and don't leave harsh chemicals on them for any duration.
Also be careful when applying tyre cleaner, I use a VW cleaner which I apply sparingly and dry off so it doesn't drip onto the alloy.