Fuel economy and performance suffer when rims are upsized (plus-sizing) because heavier rims weigh more. Car and Driver measured a 10-percent decrease in fuel economy and a 4-percent decrease in performance when it tested 19-inch tires compared to 15-inch tires on a Volkswagen Golf.
Plus-sizing is commonly done to improve a car's handling and appearance. Benefits of plus-sizing include improved cornering ability, better braking, a more comfortable steering feel and a smoother ride. Consult the manufacturer for the best performing rim and tire size combinations for your vehicle. Tires are typically downsized for winter driving because narrow tires tend to perform better on snow and ice.