Gunk on my tire

A few miles from the end of my ride on Saturday, I noticed a big patch of something on my front tire. Apparently I rode through something gooey and sticky. It looks like chewing gum, except it was a big patch -- 3-4 inches long and a couple of inches wide.

I removed most of it with paper towels, but there's still some gunk stuck to the tire. Anyone have any suggestions for how to remove it?

Thanks!!

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Scrape carefully with a razor blade or putty knife and just let the rest wear off? I wouldn't want to put any kind of solvent on a tire. I hate it when my pretty blue tires get tar on them, but I just let it wear off.