Originally Posted by
noglider
I heard folklore that said that leaving the plastic on could keep the humidity of the glue under the patch, making it lose its stickum. Is that merely a rumor? I'll be glad to learn I can leave the plastic on!
You don't have to worry about humidity. The glue is hydrophobic, i.e. water hating, and the solvent for the glue should have evaporated before you stuck the patch on. The plastic
will crumble and break up in the tire but that doesn't cause any problems other than having small bits of plastic in your tire.