When looking at a new car or EV, you may notice that some trim levels have larger tires than others. For example, the 2023 Honda Accord Hybrid has 19-inch wheels and tires, while the EX-L has 17-inch ones. Comparing the fuel economy figures between these two models, the Accord Sport gets an EPA-estimated 46 mpg in the city, while the EX-L is rated at 51 mpg.

That’s a big difference, and the only change between the two cars at the wheels and tires they are rolling on. But why do larger wheels and tires affect a car’s fuel efficiency or EV range so much? Here are three reasons why.

1. Larger tires are heavier and require more energy to move

The main reason larger wheels and tires on a car kills its gas mileage is simple physics. The bigger the wheel and tire setup, the heavier they will be. As such, the car’s hub will require more energy to get the wheels moving, thus hurting the car’s fuel efficiency or EV range.

2. Larger tires are wider, which creates more wind resistance at higher speeds

A larger wheel and tire setup doesn’t only have a larger diameter, but it’s also wider. And while that wider width could make the car look better because the wheel sits flush with the fender, it also creates more wind resistance. While the car drives, the wind resistance makes it less aerodynamic, which in turn hurts its fuel efficiency.

3. Bigger tires have a larger contact patch with the ground, which creates more rolling resistance

The physics lesson continues; larger tires have a larger contact patch with the ground. And while that larger contact can equate to better performance in a motorsport situation, since there’s more traction, it also creates more rolling resistance. That resistance leads to a drop in fuel efficiency or EV range.

This is also why many automakers outfit their EVs and hybrid cars with low rolling resistance tires from the factory. According to Discount Tire, “Tires with low rolling resistance often feature thinner sidewalls, shallower tread blocks, and specialized rubber compounds. These features work in tandem to reduce the energy required to spin the tire, thus increasing fuel efficiency.”

How much do larger wheels and tires affect a car’s fuel efficiency?

There’s no set percentage or amount that a larger wheel and tire setup will affect a car’s fuel efficiency since every car is different. However, the editors at Car and Driver tested different wheel and tire setups on a 2010 Volkswagen Golf and saw a two-mpg difference between the set of 15-inch wheels and the 19-inch ones.

However, the difference can be greater depending on the type of tires used. As in the first example with the 2023 Accord, there’s a whopping five mpg difference between the trim levels. Some of the difference could be due to the type of tires Honda installed on each trim as well. Either way, if better gas mileage is what you seek, a smaller and lighter wheel/tire setup is the way to go.