Effects of Upsizing Tyres

Several car owners ask CarToq about how they can upsize their tyres, as with all things, there are negative and positive effects. Here we look at the pros and cons of doing so and thus help you further in deciding if you should be upsizing or not.

Effects of Upsizing Tyres

Earlier, we discussed on how to go about upsizing tyres and rims: All you wanted to know about upsizing tyres

Pros of upsizing

Car manufacturers use tyres and wheels for cost-cutting by supplying narrower wheels and tyres which are safe enough in most conditions. However, these may not necessarily be safe for your driving style and other tyres may be better suited for your specific needs. Here we take a look at some of the benefits of upsizing.

Also read: Why some common car modifications are illegal

Better Grip and Traction: “The more rubber on the track, the more grip you get”. This is a line commonly used by race engineers and does hold true in the real world too. Wider tyres offer a better contact patch on the road thus making the car more planted; offering you more grip and traction. Especially if you car’s engine produces more than average power. All that power needs to be transferred onto the road and wider tyres help do that.

Better Cornering: Body roll is directly associated with the stiffness of the suspension but tyres also play an important role here. Higher sidewalls induce more flex, due to which the car may roll more during high speed cornering. On the other hand, low-profile tyres have lesser but stronger sidewalls thus minimizing body roll to give you better stability around a tight corner.

Also see: Make your car’s suspension stiffer or softer

Better Braking: You might have a fast car but you won’t be able to drive fast if you can’t stop in time. Better brakes can help you in such a situation but an easier way to reduce braking distance is by going for wider tyres. Again, due to the larger contact patch and more grip, wider tyres help in effectively reducing braking distance, also reducing chances of skidding.

Better Looks: Wider low-profile tyres are usually replaced along with bigger alloy wheels. Lower profile tyres also enhance the look, design and size of the wheels and car overall as low-profile tyres have smaller sidewalls and lesser rubber to show.

Better Fuel Efficiency: In some cases, installing bigger wheels may increase fuel efficiency. That happens if the overall diameter (OD) of the wheel and tyre is more than the stock tyres and wheels. This is due to the change in gear ratios. Due to the bigger OD, the wheel will travel more distance with each revolution than the stock tyre.

Related: How to increase the ground clearance of your car

With stock OD, hypothetically, 1 rotation of the crankshaft would be equal to 1 rotation of the wheel. With a bigger wheel, that same single rotation of the crank would be equal to less than a single rotation of the wheel. This would be due to the increase in diameter. This means that the crank would now need to put in more effort to turn the bigger wheel. That extra effort is governed by the amount of throttle input.

Assuming that your driving style remains unchanged and that you will not be accelerating more, your mileage will increase (by covering more ground with the bigger wheel).

In the real world, this will only happen in the top gear as in lower gears you will feel a loss of power. Similarly if the OD is reduced then, acceleration will increase and top-speed will drop, decreasing fuel efficiency.

However, this is not a recommended practice as it requires good understanding of your car’s gear ratios. 

Also read: Signs that it’s time to change your tyres

Now, let’s take a look at the cons of upsizing

Reduced Fuel Efficiency: Wider tyres with stock OD may reduce fuel efficiency as the car now has extra grip which needs more power to move and more power means more fuel. This will be more evident while driving in stop-and-go traffic where the engine will need more revs to move due to the wider and grippier tyres.

Steering: Wider tyres will make the steering heavier due to the larger contact patch.

Wet weather driving: Wider tyres are at a higher risk of aquaplaning (also called hydroplaning) again due to the wider contact patch. So, if you live in a city with constant rainfall, you might want to avoid wider tyres unless they are specially designed for wet weather driving.

Also see: Tyre buying guide – What type and brand to choose

Extra-wide tyres and wheels: These tyres may look cool but will damage the fenders and put extra burden on the suspension and axles, apart from the negatives listed above.

Upsizing is a calculated practice which should be done according to the needs of the car and driving practices more than just aesthetic appeal. One can benefit largely from right upsizing while on the other hand one may end up regretting the same. We hope the above information helps you decide better.