I don't -think- that it will acyually dissolve the rubber used in tires. Well, not all of the rubber compounds in the tire (although it's particularly hard on natural latex). But what it will do is cause the rubber to harden faster than it would from simple age.

The rubber compounds in tires are not 100% cured. Mostly, but not all the way. There are oils in the rubber that allows them to remain flexible, soft, and grippy. These oils will naturally evaporate with time, which is why rubber hardens with age. (Well, this plus oxidation makes them harden in time...)

The acetone (a solvent) mixes with, breaks down, and thins some of these oils. When the acetone evaporates (which it does, you've noticed I'm sure, very quickly) it takes some of the "good" oils with it. The result, dry, hardened tires suffering from accelerated age.

Yes, the rubbing alcohol does this too, but to a much smaller extent. It's also a lot less hard on the person using using it than the acetone is.

You can also very effectively thin the alcohol with water; they mix very readily. The sharp of eye would also have already noticed that most bottles of rubbing alcohol already are mixed with water. Usually about 30%.

-Erik