Dude, white spirit, a rough cloth and a butterknife with lots of elbow grease.
Although, the glue i had to remove was some very hard red stuff.
Is the stuff you're talking about not very solid like almost gooey? It sounds like what's on a set of rims I've got that I'm in the process of removing the glue and polishing. If I find something that works better I'll let you know.
I think one of the tires I was riding Mayday had that stuff on it. I removed as much as I could without damaging the tire and glued over it, so far so good.