# Do Bigger Tires Affect MPG? (All You Need To Know)

Before upgrading the tires on your car, there is a lot to keep in mind, as changing the size of the tire just slightly can affect your car in big ways, such as going up in tire size.

However, exactly how do bigger tires affect mpg? If you’d like to find out, keep reading this article to see what I gathered on this topic!

## Do Bigger Tires Affect MPG?

Generally, bigger tires decrease your mpg a little bit because they’re heavier. They also have a higher rolling resistance due to this added weight. Therefore, your engine has to try a bit harder to get your tires moving. However, there are many other factors that also affect gas mileage, such as your tire’s treads.

### How Do You Calculate MPG with Bigger Tires?

Calculating your new mpg with bigger tires is pretty simple. First, figure out how much bigger the new tires are in percentage.

For instance, they may be 10% bigger than your previous tires, so you simply multiply your mpg based on that percentage.

If you want to find out how long your car can travel, simply multiple your new mpg with your car’s gas capacity.

However, this isn’t terribly accurate all the time, as you’ll also need to factor in the weight, which will decrease your mpg somewhat.

Some tires are heavier than others while not actually being much bigger. Therefore, these will have a lower mpg than tires of the same size.

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Note that there are lots of other factors that affect mpg. However, with that said, calculating off size alone is at least somewhat accurate.

### Will 33-inch Tires Affect Gas Mileage?

Generally, you can expect to lose a few miles when switching to 33-inch tires from larger tires.

However, this difference usually isn’t huge (it may be a mile or two when switching from 35-inch tires, for instance).

The type of tire also matters. For example, some tires are made for driving on the highway, while others are designed for off-roading.

For the most part, these off-roading tires will not be as fuel-efficient on the highway as other tires.

Therefore, if you’re interested in saving money on gas, you should aim to choose the right kind of tire as well.

Some tires are also heavier than others. If your tire is particularly heavier, it will take more energy to get it to move. Therefore, you can expect the tire to have worse mpg.

### Will Bigger Tires Hurt My Transmission?

While you may be interested in using larger tires to boost your mpg, you should consider the potential damage to your transmission as well.

If the tires aren’t changed properly, they can cause issues such as transmission failure. Transmissions need regearing after tires are changed, because if they’re not re-geared properly, then your transmission may fail.

Simply put, the bigger tires will damage the gearbox, meaning the few dollars you’ll save on gas likely won’t make up for these transmission issues. Therefore, you’ll end up losing money in the end.

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### Do Fender Flares Affect MPG?

Fender flares may have a very small effect on mpg. However, this effect is thought to be extremely small (you likely won’t find yourself needing to fill up more often, for example)

### Do 20” Wheels Affect Gas Mileage?

Changing the wheel size on your car will always affect gas mileage.

However, which way it changes can vary substantially. In most cases, upgrading to 20” wheels often decreases your gas mileage, because the wheels are not as peppy.

Therefore, your wheels won’t react to the road the same. However, this change is likely only going to be 2-3 mpg, which probably won’t matter much.

Therefore, you probably won’t notice a huge difference once everything is said and done, meaning this slight change in gas mileage doesn’t need to be part of the decision-making process in most cases.

To know more about tires, you can also see our posts on what are bias tires, what are XL tires, and if bigger tires affect speedometer.

### Conclusion

Anytime you upgrade your tires, you can expect your mpg to decrease. Often, this decrease will only be by a mile or two. However, the difference between tire sizes will determine the difference between mpg ratings.

There are many factors that affect mpg, such as how you drive and where you drive. In fact, these other factors will likely have more of an effect than the size of your tires.