Selecting Right Tire Size For My Car: The Beginner’s Guide

Right tire for mercedes G class

Do you face steering or balance issues while driving? Do you know how many serious car crashes occur because of vehicle rollovers? Well, more than 3% of the severe crashes are due to loss of steering control and car rollovers.Choose a right tire before you upgrading your wheels.


The only way to stay miles away from such a risk is to choose the right tire size that helps you keep control of the car. A cautious and expert driver would always know when the tires are not right for the car and need to be changed.


However, even if you’ve just begun driving, don’t worry! We will help you on how to find the right tire size for your car. Whether you’re stuck with where to find Tire specifications or can’t read the manual, we are here to take you to step by step. Scroll below for a complete guide!

  1. Manufacturer’s Advice: The Tire Size Guide

The Tire Size Guide you get along with your car is the best source in this matter. No one but the car or tire manufacturer would know what’s best and accurate for your car. Oftentimes it is hard for people to understand the complex structure and terminologies used in the manual.

There are usually only two places inside the car where you can find your guidebook. It could either be inside the driving side’s door or in the sidewall of the tire.

There are some key parts of a tire that you should be aware of. Knowing these numbers can help you choose the right tire size for your car even without the help of an expert!

Rim Diameter: This is the outer part of the wheel that handles the tire firmly. The right rim size can save you from many mishandlings and control issues.

Ply Rating: Ply rating counts “rubber” layers on the tire. This is crucial to notice if you’re buying a heavy jeep tire. A good average ply rating is 8 layers of rubber.

Carcass: This is also called the “casing” of the tire. It comprises the most important parts of a tire, plies and wire beads.

Radial: positioning of the ply cords of a tire. Radial construction is a necessary tire specification to note while choosing the right tire size for your car.

Aspect Ratio: the ratio between the cross-section width and cross-section length of the tire.

  1. Radial Construction and Rim Diameter

Radial construction refers to the design used in placing the ply cords in a specific direction. In this type of construction, the ply cords are situated in a “radial” direction. Moreover, the Plies extend “bead to bead” – as technicians might call it – at 90 degrees to the center of the tire. This is good to know when choosing a tire for any type of vehicle.

Another useful feature to look for is the Rim Diameter. This is also called a wheel diameter or ‘diameter code’ that is measured in inches.

Make sure to check the diameter code of your tire. It is written on the guide or the tire itself and is ideally between 14-19 inches. An example of how Rim diameters are written is:

“R17”, meaning the diameter code is 17 inches.

3. Road Conditions and Weather

Driving on a clear and smooth urban road or flyover isn’t the same as passing by snowy countryside. You need to choose tires that can handle a ride on tough and unusual surfaces.

Driving in snow or on wet and oily surfaces has its own risks, and it is crucial to look out for any loopholes in your car’s functioning! Choose a more tough rubber tire if you’re driving in dense mud and wet snow.

4. Three “T’s” Of Tire Specs

Treadwear, Temperature grade and Traction grade are the three main specifications of a tire. Even the government in many places uses these figures for grading tires of different companies. There are certain ways on how to read tire size and tire grades.

Temperature grade is measured in degrees, maximum heat the tire can handle. If the limit is very high, you can travel around the desert and enjoy a whole tour! On the other hand, treadwear is measured about its baseline number.

This is the measure of the longevity of your tires. By looking at the treadwear grade or its relation with the base number, you can estimate how long the tires will last.  A treadwear of 100 is considered the least (baseline).

If the tread wear of your tires is more than 300, it means they will last more than three times the average. This is certainly good news for you! Always look for the best value for your money when choosing the right tire size for your car.

Lastly, traction grade measures how good the tire can handle friction levels. On a wet or oily road where friction is least, you need a good traction grade to enjoy a smooth and safe drive. On the other hand, a low traction grade can cause serious accidents, especially on wet roads.

These three figures are also called the “Uniform Tire Quality Grading” measure and are widely popular across many states. These are crucial for the government to measure such tire specs and for a buyer to stay far from serious risks while driving.

5. Load Index

The load index is the limit of load or burden that it can handle. For loading trucks or heavy vehicles, tires with a large road index are preferred.

This measure is crucial because loading the tires above their capacity can cause controlling issues for not only the driver but the car or vehicle’s engine as well.

Staying aware of the perfect load index your car requires is an important step if you’re wondering how to find the right tire size for your car.

6. Speed Index

The speed index is the capacity of speeding of the tire. There is always an extent to which you can speed on a certain company’s tires. Speeding causes heat, friction and other physical changes that impact the body of the tire.

Therefore, be careful with how often you Overspeed with a certain type of tire. After all, there’s a reason they have separate tires for racing around!

Now that you’re aware of the key specs of a good tire, make sure to check every detail when you choose!

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