Of course you're right re nitrogen
Someone, maybe an engineer, explained to me filling jet aircraft tyres with nitrogen for the reason I have stated YEARS ago and I just didn't think it through and the Tire mart fella mumbled something along those lines a few weeks ago and it just washed past me untested...everytime that happens I live to regret it
The simplest answer is nearly always correct...just the buffer built in for pot holes more than covers any increased pressure differential from climbing a mere 10000'...or even 30.
Bloggs...sorry
