thanks for all the responses on nitrogen in tires. It makes sense.

What if you get a hole or a leak and you need to fill it up? are they safe to mix and such?

Air is like 80% nitrogen, so yeah. Should be fine, it'll just behave a little more like a traditionally filled tire.

If you request no weights on the outside, some places try to do all the balancing on the inside. this very seldom works well. Sticky weights behind the spokes on the inside of the rim work the best. And at high speed have less chance of coming off. Good job Boost for remembering me.

You mean there was a choice about where the weights go?

Tires on my Jeep are filled with nitrogen so it has those stupid green valve caps too Since it'* on the Jeep it doesn't bother me too much since more times than not they're coverred with mud

Mr. Bill, those green valve caps need to go on Ramani'* vehicle

Here'* what they look like if you haven't seen them

The tires on my SSEi were weighted with a combination of inside, outside, and stick on weights during road course balancing (out of necessity for that type of balancing).

Well...Monday being Halloween I was unable to drive the car much. Too many little ones out and about.

Ran to the post office last night.... I almost forgot how nice quality tires felt on a car. Bothers me that the previous owners on both my cars put cheap tires on...

Look out world..I'm on rails.

(Aaron..let'* take that cruise down the on ramp again.. This time we could really get moving)

ok, so if the air we breathe is 78% nitrogen, then after X period of time, the smaller molecules, 22% (for the sake of argument) will leak out before the nitrogen, correct?

to keep things simple lets imagine that there are 100 air molecules in the tire, 22 of which are non-nitrogen that will leak out faster

this leaves the tire 78% inflated

a properly maintained vehicle will have the tires checked and filled regulary, so that the tire will get topped off with another 22 molecules to fill the void left by the assumed smaller than nitrogen molecules, with my calculations this would add roughly 17 nitrogen molecules and 5 misc others. thus after one tire pressure check and refill, the tire will contain the origional 78 molecules plus the new 17, totalling 95, or 95% nitrogen

this 95% is probably just as much as a tire filled with nitrogen will have due to the initial space in the tire filled with ambient air before inflation.

Therefore, i hope no one pays extra for something that can be accomplished through one pressure top-off