Should you change your original tire size to a bigger one? What are the Pros and Cons?

Tire upgrades – Yay or Nay

Tires are a part of your automobiles that require proper maintenance as a lot of factors like the vehicle’s braking, ride quality, etc. depend on its size and running condition. Most people tend to use their stock tires but it is an increasingly popular trend to upgrade your tires to a bigger size currently.

Ford Car Tyre

Tire upgrades are not exactly mandatory as the stock tires the car comes with are more than good enough. The stock tires are fitted onto any model after their balance, performance, quality is tested in depth. So most tire upgrades are commonly done to enhance the car’s appearance more than its performance.

Just like any other upgrade, this also has a number of pros and cons relating to various factors. The final decision of choosing to change your normal tires for bigger ones will wholly depend on your preference.

This article has a detailed explanation of how you can upsize your tires and also of the advantages and drawbacks of upsizing them.

Tire Markings

Before we go on to upsizing them, let us take a brief look at the markings on them and what they mean.

Car Tyre Upgrade

Tire Width: The first number following the name of the tire indicates the width of the tire in millimetres

Aspect Ratio: This is the first number after the / and indicates the height of the sidewall in percentage.

Rim Diameter: This is the number with the letter ‘R’ in front of it. It indicates the diameter of the rim in inches.

Load Index: This indicates your tire’s maximum safe weight carrying capacity and is mentioned right behind the rim diameter.

Speed Index: It is denoted by a letter that indicated the maximum sustained speed for the tire when the vehicle is fully loaded.

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Determining the Right Size for your Tire

  • It is imperative while upsizing for the width of the new tire to stay within 3% of the total diameter of your stock tires.
  • Another rule to remember is that your tire width and sidewall height are inversely proportional. So when you increase one, the other has to decrease to maintain the balance.

You can upsize your tires by either of the following methods.

  1. Wider Tires While Retaining Original Wheels:

Here, the alloys or the rims remain untouched and wider tires are chosen to be fitted. Keep in mind that the new, wider tires must remain within 3% of the total diameter of the stock tire.


Your tire size is 185/65 R15 and the total diameter is 24.47 inches. From this, you can get the following,

Width of the tire – 185 mm

Sidewall Height – 65% of thread width

Rim size – 15 inches

Say, you add 20 mm to your stock tire width making your new tire width as 205 mm.

This will require you to reduce the sidewall height by 10% which means your new sidewall height is now 55%.

In this method of upsizing tires, we are keeping the same rims as from our stock wheels. So the maximum upsize we can obtain for a stock tire of size 185/65 R15 will be 205/55 R15.

2. Upsizing both Wheels and Tires:

The other way to upsize the tires is by modifying the company fitted wheels in diameter. The tires known as low-profile tires are fitted to the upsized rims. We need to keep the same factors that we utilised as for the previous example.

Let’s look at an example to understand this. For a 185/65 R15 tire,

The total diameter will be calculated by: (Sidewall width x 2) + Rim diameter

That is, the total diameter for our tire will be equal to 25.469 inches

Pros and Cons of Tire Upsizing

Check out the pros of upsizing your tires first.

  • It gives your car a bold stance and makes it cooler than it was.
  • Tire upsizing is one quick and easy way of making your car stand out. It is a simple way of modifying it to match your personality.
  • The wider tires also offer more grip on the ground due to the increase in the surface area of contact. It should technically offer better control over the car and stability at higher speeds.
  • It also brings down the braking distance and safeguards you from skidding when you brake at higher speeds.
  • Since widening the tires makes the sidewall flex thinner and eases the cornering for the driver.
  • Moreover, upsizing is a sure way to boost the overall performance of your car, especially for drivers who tend to understeer or oversteer while driving. The wider tires compensate for your steering techniques and balance the vehicle.

Now, for the Cons of Upsizing your tires:

  • Tire upsizing in your vehicle is going to cost you more than the stock tires. How much higher will depend on the model of your car and the type of tire you choose.
  • With bigger wheels, you have significantly increased the weight of the vehicle’s body and thereby the load on its engine. This will in turn pull down the engine performance and reduce the acceleration capability of your car.
  • Wider tires mean more stability. It also means you need to have a heavy hand on the steering to control the ride. This will hinder drivers who are used to driving around with a light touch on steering whereas those who usually oversteer will find it as an improvement.
  • The fuel efficiency of the car will be reduced by tire upsizing as the larger wheels with wider tires have increased grip on the road and a negative effect on the car’s rolling resistance. So the car automatically revs more than usual to keep moving and uses up more fuel.
  • A failed tire upsizing will mess up your speedometer reading. So make sure you select the right tires that match your car’s proportion for it to keep performing efficiently. When the new tires are larger in diameter than what is recommended, your speedometer is disrupted and other systems like ABS, ETC, TPMS and ESP are also affected.
  • The ride quality of the car is affected and not always for the better. Since the sidewall length is reduced, the sidewall flex becomes next to nil for the vehicle to absorb the shock from bumps on the roads.

Now, that we have given you all the factors to consider, what will you decide with your tires? Going for bigger ones or still keeping your stock tires?

If you have decided to upsize, then always consult a professional expert before settling on a size for the new tires.

Let us know in the comments section if you found this article useful.

Read CarJasoos Auto Blog for more similar articles.

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