hi leasaunce.... on the topic of filling your tyres with nitrogen, it means first you have to take all the air out first and then refill the tyres with nitrogen, rite? and to do it, you'll have to elevate the car, which means the car (and the wheels, of course) would be off the ground, rite? to my knowledge, once the wheels are off the ground, they are no longer "in-line" which means after filling the tyres with nitrogen, you would then need to redo wheel alignment...you agree? did you have to redo wheel alignment after filling your tyres with nitrogen? thanks, S1LV3R