Tire (Mario Kart)
From the Super Mario Wiki
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Tires are vehicle parts that appears in all the Mario Kart installments, but are only customizable in Mario Kart 7 and Mario Kart 8. Tires alter the speed, acceleration, and weight stats. The tires have changed constantly throughout the two games, varying in size and features.
Mario Kart 7
The tire customization first appears in Mario Kart 7. Each tire affects the speed and weight of the vehicle.
Mario Kart 8
Tire customization returns in Mario Kart 8. The stats have not changed much from the previous game, but in anti-gravity the speed and handling are affected. In addition to the new tires, every customizable tire from Mario Kart 7 excluding Mushroom and Red Monster reappears in this game.