Originally Posted by
FBinNY
Toluene is a common solvent for rubber based compounds. If that's what was in the solution, commercial paint thinner should help remove it. In any case, as you try stuff, be aware to NOT USE any caustics like lye, oven cleaner, etc, since these will attack aluminum rims.
Toluene should work, but might not be readily available. I have found xylene at my local hardware store, and its solvent power is close to toluene (because it is close in chemical structure).