ok, gotcha. Mine have plenty of tread on them, but I've never heard of grooving. That's great to know about! I wasn't concerned so much about the tread as them being old, dried out, cracked and unevenly worn, which I think causes some driving vibration and a wobbly driving feel. I'm guessing that's not such a great thing for the health of the suspension, and other parts, especially for a '99. It's really the long drives, and even shorter high speed highway drives that make me uneasy. Here in New Orleans we're going to hot soon and stay hot for a while, so if heat increases the risk of blow out... I also didn't consider selling them. What do you think I should list them for, $25\tire, and hope to get $20? Are there any products that might rejuvenate the rubber at all? I'm getting new tires tomorrow morning. I'll post pics.