About a year ago, in lieu of using the Ultraguard (because I didn't have any), I used leather dressing on the rubber housing on one of my Deltaflex reflectors. There was plenty of cracking in the rubber. The cracks seemed to heal for the most part, with about 3 applications in a weeks time. The worst ones were about 85 percent better. Now when I look at it, I'm still as pleased with the results, but gave it another helping of leather dressing just for good measure. I saw no deterioration. Would this work on tires? Probably. Use this suggestion at your own risk, as I claim no responsibility for damaged parts.