I was told this morning of several ways to remedy this problem. I just found out this morning, so I haven't had a chance to try it for myself.

1) You can put them in a pot of hot water (almost to the point of boiling the water). Let them sit a while and it is supposed to soften the glue.

2) You can put them in the oven on a low setting, and the heat is supposed to soften the glue.

3) This actually makes more sence to me. Put a little acetone in the bottom of a coffee can, and set something in the bottom so your tire will not touch the acetone. Put a lid on the can and let it sit until the glue softens. The fumes from the aceton will soften the glue.