For example, larger tires decrease your fuel economy because they are heavier, while smaller tires increase fuel efficiency. Bigger tires also have a higher rolling resistance than smaller tires which means they require more resistance and effort to get them rolling. ... Tire treads can also impact your fuel economy.

Does tire size affect Miles?

Remember, power and economy are affected by transmission, drive axle ratios and tire size (revolution per mile). Change one, and you throw the equation off. With today's new tires, there is virtually no difference in mpg due to tire size.

Do bigger tires add more miles?

If you don't recalibrate the odometer, bigger tires won't affect it. Changing your car's tire size to bigger ones will not necessarily automatically affect your odometer because you still have to recalibrate it. However, while the odometer isn't automatically affected, the actual mileage of your car is affected.