I have a set of wheels and tires originally off of a Roush 428R and i need to top off the tire pressure. Are these tires filled with nitrogen or plain 'ol air? And if it is nitrogen, can I add regular air to top em off?

Thanks!!

 

air is 70$ nitrogen so topping them off with air is OK.
They will have green valve caps if they have pure (ha ha) nitrogen in them.

 

Air is actually ~80% nitrogen, so you will be fine. I had nitrogen in my tires, but then I moved and none of the dealerships had nitrogen so I just used regular air.

 

Is a 100% nitrogen fill REALLY noticable?

 

I just had mine filled with nitrogen at the dealer because they screwed a few things up, and i cant really tell a difference. Also my valve caps are blue

 

If their filled with nitrogen it should have a green or blue valve cap, yes you could use air if nitrogen not avalible, their is another thread with nitrogen air debate it works for me in Fl.

 

awesome, thanks for the info everyone

 

there is actually 78.09% nitrogen in air. god!

 

TBH wth is the point in doing nitro fills(i have reg air had nitro before and i feel no dif) >_>

 

Supposedly, the advantages of nitrogen are:

1) Less variation of tire pressure with temperature changes.

2) Less chance of the tires rotting on the inside.

3) Less pressure loss over time. Tires filled with regular air tend to lose .5-1 psi per month even if the vehicle is not driven.