Goes hand in hand with each other. While being spun on the balancer (in a road force balancer) there is a wheel that comes down and rides on the tire tread applying pressure (hence road force) to the tire during its spin balance.

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'04 Sonic Blue Ranger, 2 tone Katzkin leather seats, Custom Ford script spray in liner, Spyder LED tails, 8000k Morimoto HID's, LED 3rd brake light + signal mirrors, 06 badges, grille, corners, K&N intake, Magnaflow exhaust, AR Shelby series 17x8 chrome wheels, Pioneer P4300DVD, Hybrid Audio Technologies Imagine 6.5 components up front and Pioneer TS-D681R's in rear, Alpine PDX-V9 5 channel Amp, Image Dynamics IDQ 12" sub. Optima Red Top, "Painted to match" interior pieces