So, Ive been running fine on my crossmax xl ust rims with bonti tubeless tires. Well, wanted to run during the snow season here in wisconsin and try some different tires. Its been a while since I mounted the bontrager tires. The other set of tires I have are with tubes, so I figure, pop out the valve and core, did that. Then, got a different set of tires that are tubeless, ok, drop the valve and core back in. After struggling to get the tires on, the threaded valve unit doesnt hold air. I hold the core, screw the unit down, but it just twists, no real tightening feeling, but air is getting out? What am I missing here? Its hard enough to get the tire to initially hold air, then the valve/core leaks like nutz! Any advice. Thanks.