Not any more.
"Stagger" is a technique used to make race cars with bias ply tires more stable. You put either bigger tires or higher tire pressure on the right side. Sprint cars and other series where they're not trying to "make everyone equal" use bigger tires; because NASCAR has always mounted the tires for you they put more air in the rights.
This has naturally led to some of the more vicious wrecks in the history of the sport - if you are running five pounds of stagger and accidentally put a right-side tire on your left front, you go straight into the wall at full racing speed.
They don't use stagger with radial tires because it doesn't do anything for you.
Firestone tire is a NASCAR sponsor. Some of the cars use firestone tires other cars use NASCAR tires. Firestone also sells NASCAR tires in addition to their own brand.
They fill their tires with nitrogen.
For maximum grip.
NO
Yes the new tires are faster and do not slip.
About 1500 dollars a set.
1995
The biggest tires that are common have about an 29" outer diameter.
Probably sell them as souvenirs.
Ill advised, it can wreck havoc with suspension and drivetrain.
It is just a form of celebration.
Unlike the Nascar Nationwide Series, the Sprint Cup Series does not use rain tires.