I'm planning to build a few 60's and 70's sprint cars that ran on dirt tracks (Opperman, Snellbaker, Nace). I've been looking for suitable rear tires and haven't found any yet. I've ordered the correct knock-off wheels from Larry at Big Donkey, but the tires he sent me are resin versions of the Revell sprint kit tires and are too wide for that period of time. Today I took a rear tire (slick, no tread) from a Tobias modified kit and sliced and diced to narrow it down and am actually happy with the result. It's about 1 5/16 tall and 7/16 wide, so it looks right to me for a right rear sprint tire. I then took a shot at adding grooves to it. I measured and marked three grooves around the circumference, then started the grooving process with a fresh #11 X-Acto blade (used both the front and backside of the blade). Once I had a groove started, I switched to a razor saw blade. Once those were done, I added some diagonal grooves. They weren't cutting deep enough, so I tried a fiberglass cut-off wheel in a Dremel. That tended to melt the tire plastic as it cut the groove. The end result looked messy and uneven.
Anybody got any tricks that they have used to cut realistic looking grooves? I'm open to any suggestions you want to toss my way!