Why does tire size effect fuel economy?

All-season tires

The reason tire size affects fuel economy is because tire size plays a role in rolling resistance which in turn has an effect on fuel economy. Rolling resistance is the combination of forces that work against the forward motion of your vehicle. The weight of the vehicle, gravity and inertia, the amount of friction between the tires and the road surface, and air drag all play a part.  With lower rolling resistance tires there is increased fuel efficiency or in the case of electric cars an increase in the distance they can travel on one single charge. This makes low rolling resistance important for hybrid and electric cars as well.

So, what happens if you put larger than recommended tires on your car or SUV? Larger tires decrease fuel efficiency, this is because of the simple reason that larger tires are heavier than smaller tires because they have higher rolling resistance. It takes more force to move the larger tire from its resting position. Also, the wider the tires the higher the rolling resistance is so the engine has to work harder to move the tire.

It is therefore very important to stick to the manufacturer’s recommended tire dimensions when buying new tires for your car especially if you have a hybrid or electric car. If the recommendation is for the dimensions 265/70R17 and you are in the market for all-season tires, then you need to buy 265/70R17 all-season tires. This assures that you have tires that are the most adapted for your car and will allow you to benefit from the best fuel efficiency.

If you don’t follow manufacturer’s recommended tire dimensions, then you would be jeopardizing both fuel efficiency and handling of your vehicle. This is because the tire size can affect everything from braking (ABS), handling and your odometer, for instance, a larger tire reduces the car’s effective gear ratio which can in turn negatively affect the transmission and even the braking system. In addition, a wider tire can put your car in danger of hydroplaning. With electric and hybrid cars having battery packs that already make them heavier and slower to stop than regular combustion engine cars, the risk of hydroplaning is already increased.

When it comes to car tires, size does matter so for the best handling, performance and fuel efficiency stick to the manufacturer’s recommended dimensions. It is also important to get tires with low rolling resistance as not only the size plays a role in rolling resistance. How the tires are made, the rubber compound, the tread pattern and the stiffness of the tires, also play a role in rolling resistance. In general, all-season tires have lower rolling resistance then winter tires or all-weather tires, as they have a less aggressive tread pattern.  Low rolling resistance tires make a lot of sense as they improve both fuel savings and reduce pollution which is better for the environment.

For more information on low rolling resistance tires, visit: nokiantires.com

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