Originally Posted by
dscheidt
I wouldn't accept a tube that leaks 2 psi overnight on a mountain bike. On a road bike, with skinny tires at 100 psi, I'd exepect that. I run michelin airstop tubes, mostly, my bike with 700X50 tires loses about 2 psi a week (40 psi front, 50 rear). That's checked inside, so temperature isn't an issue. I would expect to be able to find a 2psi overnight leak with leak detection fluid, but maybe not in a sink.
That’s why I said that diffusion isn’t linear. A mountain bike tire at 40 psi is going to diffuse at a lower rate than the same tire at 60 psi. And the 60 psi wide tire is going to diffuse at a slower rate than narrow road bike tire at 100 psi.