How does tyre size affect fuel economy – efficiency?

There is no doubt about the fact that tyres happen to be an essential part of almost all vehicles out there apart from things like tanks or hovercraft.

When you looking to invest in a new set of tyres you might invest a significant amount of time reading through tyre specs, descriptions and in some cases watching videos.

Through all this research you have probably observed that manufacturers of tyres make use of various types of selling points for attracting a buyer these days. All this sales hype can prove to be quite confusing and overwhelming for the a buyer especially if they don’t have much experience with buying new tyres. For most people all tyres look the same. So it will be extremely hard for them to come to a conclusion regarding which brand to go for.

So why have I been talking about buying tyres. Well through our research we have found that for the majority of the drivers at present, the most essential aspects or spec they are interested in when buying a new set of tyres happens to be the fuel economy as well as the handling capabilities.

So we thought we would dedicate this article to take a look at how the fuel efficiency of an automobile is affected by the size of its tyres.

Tyres happen to be the only parts of a car that is in direct contact with the ground. In fact, it controls the performance of the vehicle to a great extent. However, the term performance is quite subjective; some people consider the acceleration when talking about performance, some will think of the traction, while others take will consider performance to relate to the affect on the car’s fuel economy. There are also some drivers who think of the comfort level of the passengers as well as the noise when it comes to performance. As mentioned we will be discussing how the tyre size can affect performance

Hows tyres affects fuel efficiency

As a matter of fact, it is possible for every aspect of the car to be affected by a change in the wheels diameter. It will influence the car’s acceleration, braking, not to mention the fuel economy as well. It has been observed that fuel efficiency can be either increased or decreased by as much as 25% simply by altering the diameter of the tyres. Several factors are going to affect this including the torque curve of the engine, the weight of the car, aerodynamics, as well as gearing.

Diameter of Tyre

Perhaps the most well-known notion on how the fuel economy is going to be influenced by the size of the tyres is that more ground will be covered per revolution by a tyre having a bigger diameter and this will minimize the overall gearing of the vehicle which will then allow the powertrain to function at a reduced number of revolutions every minute (the powertain includes the components of the vehicle from the engine to the wheels including the driveshaft.

The lower RPM (revolutions per minute) equates with reduced fuel used for moving across the identical distance. In spite of the fact that this notion comes with its own positive aspects which is genuine on some occasions, the effect isn’t a universal one by any means and is going to vary significantly according to the car itself as well as any change in diameter.

Torque curves

Perhaps the most essential factor influencing how the fuel economy of the vehicle will be affected by the size of the tyres happens to be the torque curve of the engine in relation to the weight of the vehicle. Lesser torque per revolution is produced by the engines featuring smaller displacements and it is imperative for them to spin at an increasing number of RPMs so as to generate power. In general, the engines are most productive while operating at that RPM which helps them to generate peak torque or the maximum force every revolution.

Gearing effects

It is important for any car to be geared to help it to remain quite close to the maximum torque RPM for producing maximum productivity. In case the tyre happens to be exceedingly large, the powertrain is going to generate reduced efficiency, thus needing more fuel to continue operating at the identical RPM. However, in case the tyre happens to be quite small the engine is going to spin at a faster rate than what is required so as to maintain the speed and wasting fuel as well as power in the process.

When to consider changing tyre size

Vehicles that will benefit from having larger diameter tyres happen to be those which are able to generate more torque than what is needed for maintaining speed. This will consist of vehicles featuring a final drive gear ratio which has been maximized for acceleration or diesel cars and trucks which have the ability to produce torque more than the drive speed at all times. It is possible for the vehicles which are driven by diesel to get the advantages of having a slightly bigger tyre given that their peak torque takes place at idle practically.

It is feasible to affect the fuel economy of the car by increasing the tyre’s width as well. In fact, wider tyres are endowed with the ability to create a greater surface area with the ground. In spite of the fact that it might be good when it comes to the overall performance of the vehicle, a higher resistance can be created whilst driving which implies that the powertrain needs to use more fuel as well as power so as to maintain the speed. The car will likewise be raised at a higher elevation from the road by the taller tyres which might be responsible for reducing the fuel efficiency and also enhancing the wind resistance of the vehicle.

Advantages of Increasing Tyre size

Increased fuel efficiency – when driving a vehicle at consistent higher speeds.

Increase load capacity – if you up-size the wheels then you will find that the load capacity of the vehicle will increase.

Grip – The larger tyre will allow more of the tread to be in contact with the ground resulting in better grip.

Stopping distance – the increased grip should help to reduce the stopping distances.

Stability – larger tyres will help to stabilize the vehicle/car more effectively than smaller tyres.

Disadvantages of increasing tyre size

Increased Turing circle – smaller tyres will allow a driver to take tighter corners. If you have to do a 3 point turn then it might take you a few more turns with a bigger tyre.

Speedometer Reading – the speedometer is calibrated based on the manufacturer recommended size tyres so if the tyre size is changed then it could affect the speedometer reading.

Acceleration- larger tyres will weigh more so will add to the overall weight of a vehicle. This will in turn affect the acceleration time.


In summary after going through the above-mentioned article it must now be evident that more traction is offered by the wider tyres and this can affect the car’s fuel economy. The upsized tyres are usually going to give a vehicle better grip which can result in enhanced rolling resistance (the force which resists the rolling of the tyres), and this will need more revolutions from the powertrain so as to make the vehicle move. All these will result in an enhancement of fuel consumption and this effect will be more noticeable in stop-start traffic out there.

To really gain from the benefits of using large tyres you would need to generally need to be driving your vehicle on the motorway above 60mph for consistent periods of time. If most of your driving involves short trips around the town at commuting speeds that you may not see any benefits.

When buying a new tyre you will often find that manufacturers will have fuel efficient tyres that will provide low rolling resistance and will not compromise the tyres grip. Labels on the tyres use a letter system to show a how fuel efficient a tyre is with it running from A to G with A being the most fuel efficient ant G being the least fuel efficient.

Fuel economy happens to be an essential issue for the majority of the drivers across the globe, and by driving responsively and also providing your machine with the proper tyres, you will be able to reduce your yearly fuel costs.

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