Hello,

I might be buying some used Falken Rt-215. Two tires have plenty of tread while the other two are down to 3/32nds.
I'm wondering how low of tread can you use them untill they are junk?
Would they still grip with almost no tread? (like ra1)
I will only be using them for dry track use.

Thanks!

They should work great at 3/32nds but the question is how much abuse have the seen to get there. If they've been used for previous racing events and/or are a couple years old, they could be heat cycled out and won't provide as much grip as they would be capable of. If you are familiar enough with the tire, ask yourself if you think the grip levels haven't dropped and check to see if they feel as though they've hardened up a little to tell if have been heat cycled. Either way, you can still you them, they just won't perform their best. Oh, and these tires don't like heat so expect them to drop off in performance the more time you're out on the track.