Yeah, their tires expand and grow dramatically as they travel down the track and pick up speed.

 

there tire "grow" right off the line.

 

were a bit backwards here...their tires are "wrinkle walls" and 'expand' while doing the burnout, and when they launch the tires will crush down...i have a picture of mine doing it, ill have to find it...the tire maintains the same size until they begin to slow down...

they dont actually expand or contract really, but the centrifugal force during the rotation of the tire causes the rubber to appear to stretch out...keep in mind that they also run very low air pressure in the tires, which also accounts for the odd characteristics of the tires. i only run about 16 psi in my rears, and that is high compared to some people