Went tubeless earlier this summer. Has been great up to this point. Was riding in relatively cold weather yesterday (low 20s F) and managed to get a puncture that Stans wouldn't seal - heard lots of hissing, stopped and positioned the tire so that the Stans would flow toward the hole (which it did - sealant was oozing out with the escaping air), but the hole never sealed. Popped the tire from the bead but didn't find anything sticking through (I think a small stick frozen to the ground punched through but didn't stick in the tire). I had limited air (a couple of CO2 carts) so I threw in a tube rather than hoping and trying to make the Stans seal. Guess I'm looking for input and tips regarding Stans in cold weather - or maybe this was just "one of those times" where nothing was going to help? For what it's worth, the tire in question is a UST Nevegal mounted to a Stans ZTR 355 wheel. Thanks for any help/suggestions to avoid this in the future (if possible).