I have an analog ciruclar guage with a release button. The guage will hold the last recorded reading until you release it. Costs < $10 . . .

 

I just put nitro in my tires for the first time, however recently they went low and I didn't have time to put in more. I mixed regular air with it, and brought it back up to 40psi. My question is mixing the two a bad thing?

 

here you go, this is the one I use............




http://beta.lexus-parts.com/parts_detail.asp?id=89737

 

No problem.
Plain air has nitrogen but a lesser percentage.

 

The advantage to the nitrogen is it has no water in it. Compressed air includes the water in the air, so you are putting water in the tire with the air. The water is far more heat sensitive than any of the other gases in the tire and it expands with heat raising pressure more readily than the rest of the air components in the tire. The other "advantage" to N2 is it has no oxygen to help break down the rubber. N2 is fairly inert except under certain conditions, so the rubber (or any hydrocarbon) lasts longer in a pure N2 environment. Ever see the wine preservers that are just N2 in a can? Same idea, different implementation.

I think it's funny Joeb427 says it lasts longer on a fill. We used it in racebikes for years, and the tires went flat sooner than whole air. Maybe it was because they're slick racing tires and have relatively porous sidewalls, but N2 certainly didn't last longer than whole air.