gauge pressure is a difference between inside and outside pressure. If you inflated a tyre to 70 psi, then took it into space, the gauge pressure would increase by just under 15psi, so tyre pressure would effectively be 85psi. Nothing to worry about, even if you tried cycling on the moon. High-altitude cycling should be a non-issue, especially as there is a safety factor built in to the tyre's rated pressure.
Cargo holds in airliners are at exactly the same pressure as the passenger cabin. It's far easier to pressurise the entire aircraft (cylinder shaped) than just the cabin (cylinder with flat edge)