Larger tires can in fact, increase a vehicle’s gas mileage if the vehicle is regularly traveling with consistent speeds over 60 miles per hour. Tire weight is certainly a significant factor in determining fuel economy but everything down to the tire’s tread pattern can affect a car’s gas mileage.Click to see full answer. Beside this, do you get better gas mileage with bigger or smaller tires?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.Likewise, does a car use more gas if its heavier? The heavier the vehicle is, the more energy it needs to get moving. Heavier vehicles have greater inertia and greater rolling resistance, which both contribute to increased fuel consumption. Keeping this in consideration, does higher tire pressure affect gas mileage? You can improve your gas mileage by 0.6% on average—up to 3% in some cases—by keeping your tires inflated to the proper pressure. Under-inflated tires can lower gas mileage by about 0.2% for every 1 psi drop in the average pressure of all tires. Properly inflated tires are safer and last longer.How much does tire width affect mpg?Increasing the width of a tire can impact fuel economy as well. Wider tires create a larger contact patch, the area of the tire actually touching the road. While this is good for performance, it can create a higher resistance to coasting, meaning that the engine will have to use more power and fuel to maintain speed.