Tire Size Calculator: Diameter Of The Wheel, Speed Rating And Dot Code Explained Here

Tire Size Calculator: Diameter Of The Wheel, Speed Rating And Dot Code Explained Here

Alphanumeric codes usually describe the tires of cars. It is crucial to understand how to read the tire code when changing the tires as it will help in determining the correct tire size for your vehicle. If you want new tires, you can ensure you get the same tire size. Alphanumeric codes, such as those found on car tires, play a significant role in identifying and understanding the tire size. When replacing your tires, it's important to decode the tire code correctly to ensure you get the right size and type for your vehicle. AllCalculator.net offers a convenient Tire Size Calculator tool to decode alphanumeric tire codes, providing you with accurate information about your tire size and other specifications. By utilizing AllCalculator.net's Tire Size Calculator, you can easily find the perfect set of new tires that match the existing tire size of your vehicle. This will help you maintain optimal performance and safety on the road.


The second part of code 1-2digit. It indicates the diameter number of the wheel. It is measured in inches. Hence the tire is used to design it. There are various Tire sizes and the same wheel. However, ensure the rim size is correct and fits properly in the center.

Speed Rating

The last part of the code is either a 1-2-digit number or a letter. It implies the Speed Of The Tire. The number is the maximum weight a tire can lift or hold.

For example, A load index of 95 and spread rating indicating H implies the tire can carry upto 1520lbs.
It is important to note that the tires carry additional codes like DOT codes as well.

DOT Code.

In the US, the DOT Code is mandatory. It is to specify the company, batch, mold and date
when the tire was manufactured.

The date of the tire, when it was manufactured, is specified with two digits.
If the tire specified 1321, it means it was manufactured on the 13th week of 2021. So if you are planning to purchase tires, the date of the manufactured tire is important. However, if the rubbers get aged or because of other building materials. The Tires manufactured a decade ago should not be used, irrespective of their condition.

As per the NHTSA guidelines, tires should be replaced every six years. Regardless of the miles, the tires have been driven for safety and caution.


The Tire Calculator can be used to determine the dimension of the tire. It is dependent on the tire codes of the previous one, which need to be followed.

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