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title: 'Tire Size Calculator - Calculate Your Car''s Tire Size![](https://i.imgur.com/GrOvgvh.jpg)'

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# Tire Size Calculator - Calculate Your Car's Tire Size![](https://i.imgur.com/GrOvgvh.jpg)

How Important Is Tire Size?

With a larger tire, your vehicle will have a more secure grip on the road because it covers more surface area. The more contact your vehicle has with the pavement, the better its handling and manoeuvrability. Tires are a part of the wheel setup, not interchangeable words. They are an integral part of the wheel setup. Generally, a vehicle with bigger rims can accommodate larger tires than a smaller one. It is also possible to buy tires that are smaller than your vehicle's rims, as long as their middle is the correct size though find out yours with Allcalculator.net’s tire size calculator. 

Tire Sizes: How to Read Them?

In the market for new tires, you'll find size names 235/75R15 and P215/65R15. These labels are confusing at first, but once you learn how to read them, they become much easier to understand with tire size calculator. Usually, three numbers and sometimes letters are usually found on the slash symbol's left side. The numbers indicate how wide the tires are, in millimetres, from sidewall to sidewall. The larger the number, the wider the tire covers. 
Letters on the left side refer to the type of tire. Examples include:

When there is no letter means the tire meets European standards. The two types of tires have different load capacities. The letter P indicates that the tire is made to meet U.S. standards. 
A light truck tire size begins with an "LT," which means it is meant for use on light trucks. These tires have a higher psi recommendation to handle trailers and heavier loads better than regular truck tires.
These tires are only used on trailer wheels if marked "ST.".

An example would be a tire size P215/65R15, which indicates that it is for a passenger vehicle and measures 215 millimetres wide. The right side of the slash symbol has two numbers, a letter, and two more numbers. For example, the P215/65R15 tire has a sidewall height of 65, meaning its width is 65% as large as its height. These numbers represent the aspect ratio of the tire's height to its width. You'll find the tire's construction method beside the slash, typical "R" or radial. Radial layers run across the tire, meaning they run across it radially. As you can see, the last number represents the size of the wheel the tire fits. In our example, the number 15 indicates the tire will fit wheels with a diameter of 15 inches. 

What is the effect of wheel size on your car's performance?

From the alloy rims to the tyres and all their features, such as thickness, sidewall, tread and so on, we are using the word "wheel" to refer to all components of this crucial part of our car. Media attention is often more focused on appearance than technical aspects, which can lead to a misperception that the overall size of the four wheels can impact engine performance and fuel economy more than looks. This topic applies not only to supercars but also to the regular vehicles we drive daily. 

We will explain how wheel size affects car performance with a practical example: a tyre change on a Fiat 500. In our example, the owner selected 185/55 R15 Pirelli Cinturato P1. Let's take a moment to describe what these numbers mean: the first – 185 in this example – is the tire's width in millimetres. This metric is the sidewall height ratio to the tyre's width. It indicates the tyre's internal construction as radial, while the rim diameter is expressed in inches. A wheel's total diameter must be accurately calculated with Allcalculator.net’s tire size calculator to understand how its size influences performance.

How to check tire size for your vehicle?

Easily determine which tyres fit your vehicle by entering your vehicle's details on our website. A list of all tyres that fit your car will be automatically generated once you enter your make, model, trim and year of manufacture. You may need to know what size of tyres you need; however, if you have aftermarket alloy wheels on your car that are different from the original wheels. The easiest way to determine the size of your existing tyre is simply by checking the sidewall with Allcalculator.net’s tire size calculator. Each tyre manufacturer will list all the information you need to know on the sidewall, such as speed and load ratings.