I've got 100 of the smallest size in the track of my Tundra, this is the third season with them in, and i've been super happy with them. I put mine in with a dab of GOOP adhesive on the threads, and I don't think I've lost one yet. I haven't put many miles on the sled on hard surfaces, so I can't comment on how they wear, but so far I haven't noticed any wear on them at all.