You do not drive a Formula 1 race car, you do not need to fill the tires with Nitrogen. It causes the tire pressure to not fluctuate as much under heat, but it's not that big of a deal.
I've been using 80% nitrogen for years - air. Some car racers and the aircraft industry use 100% nitrogen beacause there is no Oxygen to support combustion in a fire or oxidation on the inside of the wheel.
I think it is just another way to bull**** money out of the public. I'll stick to 80%.
On a street car it really shouldn't make much difference. On our circle track car, it does make a difference, but they are going all out around the curves all the time. We send the car out with 25 psi in the right side tires (car turns left, so the heat builds most on the right). With compressed air, after 15 hot laps, on a hot summer day, it may come back in excess of 40 psi. With nitrogen more like 32 to 35. The race tires "grow" more with extra air, and on an oval track car, the rights grow more than the lefts. This causes an increase in stagger (Rights are always taller then lefts to help turn left) which changes the way the car handles, usually for the worse. On street cars, a couple quick turns or burnouts aren't going to have the same effect with heat, and even it they do, the right/left balance is less likely to change.
I have easy access to nitrogen, but it's not worth the effort.
are they any good today the place i took my car for tire rotation was saying they are good,, i think its BS but what do you guy think,, it costs around $20 for 4 wheels i think its a rip-off
If you have fancy chrome wheels; using 100% Nitrogen will protect them. After 10 years or so of using air, your wheels will be full of rust. Performance wise I don't see it for street cars.