How does tire size affect gas mileage?

Larger tires are heavier and have more resistance on the road, which can drastically decrease the overall fuel economy of a vehicle. Larger tires may also require larger wheels, which can increase the weight of the vehicle. A driver is expectant to see up to a 10 percent loss in fuel economy when increasing a car's tire size.

When a stock vehicle's drive shaft spins, the wheels spin accordingly. Stock tires reach a shorter distance than those distances that their larger, after-market counterparts reach due to the how much less power the engine needs to exert. Because heavier tires require more power, loss in acceleration is another common effect of their size.