I've been riding every day since early last autumn,
and maybe five or six times I've used a very light weight
sandpaper to scrub the rims and brake pads, after a nasty rain ride.
Cleans them right up, and makes them quiet again.

So today, my LBS said "NO - don't do that. Use acetone
on the rims, and the sandpaper on the pads."

I asked if I'd damaged the rims; he said no, but don't do it again.
Okay - I've seen elsewhere here that Scotchbrite pads and/or
alcohol are good to clean the rims.

Sometime after the conversation (naturally), I thought,
"but won't acetone melt the tires?" (I'm no chemist)

I've got to get my rims clean after riding in the rain.
What do you recommend?