I race xc and have been using kenda kutters on the rear mounted on stock rims. After almost every race one of them is flat but the beads are still seated and i have valve stem caps on them. I have dunked both of them under water no bubbles and they hold air till the end of the next race any ideas?

Gotta be a leak somewhere. I've had to pump some tires up to 40 lbs. to find tiny punctures. And even then I could barely see the bubbles.

Agreed. Pump them suckers up, hold under water. Could be a small piece of debris
between the rim and tire. Only leaking when cornering.

i get that a lot when i run my stock front rims they dont have a leak but if i hit something they'll pop off the bead a reseat themselves and still have about half the air in them its kinda funny

yeah ill try airing them up some more and dunking them again. Could be time for bead locks, thanks for the help.

are you sure your getting the bead seated fully?

You should press on the sidewall of the tire near the bead and see if you get any bubbles like that. If so break the tire down and clean the beads.

yeah, pop the beads off and clean between the rim and tire, its something in there that leaks when you corner, my old truck once was really out of balance and couldnt be fixed with weight so we pulled the tire and there was a half pound of grass and dirt in the tire, and no it never went flat!!!

Thats what it was apparently i cliped a tree cuz there was tree bark stuffed all the way around between the bead and rim but couldnt see it unless you pulled the bead back, thanks for the help.