Your Trusted Auto Repair Shop for 40+ Years
Shop Talk Logo

Does Tire Size Affect Fuel Economy?

Car refueling at gas station

In our rapidly evolving world, fuel economy has become a crucial aspect to consider. A vehicle’s fuel consumption has a twofold impact: on our savings and the environment.

While we often focus on various factors influencing a vehicle’s fuel efficiency, we tend to overlook one crucial element: the tires. That raises the question: do bigger tires affect MPG?

Yes, the size of your tires directly influences your vehicle’s overall performance and fuel economy.

Tire Size & Fuel Economy

Understanding the relationship between tire size and fuel efficiency involves two key concepts: wind resistance and rolling resistance.

At higher speeds, a car experiences increased wind resistance, requiring it to overcome the force exerted by moving air. This resistance leads to greater fuel consumption and lower fuel economy. The size of your tires plays a role in determining the amount of wind resistance your vehicle experiences.

On the other hand, rolling resistance refers to the force exerted against the tires as they roll along the ground.

Rolling resistance is crucial for providing the grip and traction necessary for safety. However, higher rolling resistance also means more energy is needed to overcome it, increasing fuel consumption.

Tire Size & The Road

The size of your car tires plays a significant role in fuel economy.

A larger tire with more width has a greater contact patch, meaning there is more surface area in contact with the ground. As a result, more energy is dissipated to propel the vehicle forward, leading to increased rolling resistance and reduced fuel efficiency.

While wider tires do offer additional traction, this advantage comes at the cost of increased fuel usage. This is primarily due to their wider contact patch with the ground.

Do Bigger Tires Affect MPG?

While tire size significantly impacts fuel consumption, there is a common misconception regarding the fuel efficiency of larger-diameter tires. Contrary to popular belief, larger-diameter tires are generally less fuel-efficient.

The key aspect of tire size is how it affects the engine’s torque curve relative to the vehicle’s weight. The right tire size should help align the engine’s peak torque RPM (revolutions per minute) with the vehicle’s weight, optimizing fuel efficiency.

The gear ratio of the highest gear in a car plays an important role in determining RPM levels and fuel consumption. Generally, a taller gear ratio, also known as an overdrive gear, leads to better fuel mileage, reduced noise, and smoother cruising.

Generally, the ideal cruising speed for diesel engines is around 1600-2000 RPM, while for gas engines, it ranges between 2000-2500 RPM.

Effects of Too Large or Too Small Tire Diameter

It’s important to note that larger and heavier tires contribute to the overall weight and inertia of the vehicle and require extra power during acceleration.

If the tires are too large, the engine will have to work harder to rotate them and use more fuel to run at the same RPM, reducing engine efficiency.

Likewise, if the tire is too small, the engine will need to spin faster to maintain the desired speed, resulting in increased fuel consumption.

Tire Width and its Influence on Gas Mileage

When optimizing gas mileage, one of the many factors to consider is the width of your vehicle’s tires.

As mentioned above, wider tires usually increase fuel consumption. So, what about narrower tires?

Narrower tires have a smaller contact patch, leading to less friction and lower rolling resistance with the road. The slimmer shape and less weight also help reduce wind resistance while driving.

Narrow tires, known for their aerodynamic characteristics, are reputed to be eco-friendly and can yield long-term gas savings. However, they can also pose handling challenges in certain scenarios.

One quick way to optimize the eco-friendly benefit of narrow tires is to maintain proper tire pressure. Consistent tire pressure checks, ideally conducted once a month, are vital to ensuring optimal fuel efficiency and mitigating handling issues associated with narrower tires.

In Conclusion