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Tire Size Calculator

Enter tire code and specification in the calculator and the tool will describe the dimensions of the tire.

Tire Calculator
Tire Comparison
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Tire Size Visualizer
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Tire Size Comparison Visualizer
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Tire 2 Front View
Tire 1 Side View
Tire 1 Wheel
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Tire 2 Side View
Tire 2 Wheel
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(Set Size1 to OEM Size)

Alternate Tire Sizes

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The tire size calculator calculates the diameter, width, sidewall, circumference, and revolutions per mile of a tire. You need to enter the metric or standard tire size and find the tire specifications. All tire options shown by our tire size comparison calculator are within 3% plus or minus variance within the Original Equipment Manufacturer (OEM) tire size. Choosing a tire higher than the 3% tolerance may cause brake failure or other serious damage to your vehicle while driving.

How to Calculate the Tire Dimensions?

The following formula calculates the dimensions of the tire:

Section Height = Aspect Ratio × Tire Width

Tire Diameter = Wheel Diameter + 2 × Section Height

There are various terms, we need to understand for tire size conversion. These include:

Aspect Ratio:

The aspect ratio of a tire is calculated as follows: Aspect Ratio = Height of tire rim/width of tire rim The tire size conversion of aspect ratio is written in percentages. An aspect ratio of 70 means the tire's height is 70% of its width. aspect ratio   A tire size calculator comparison is the most reliable to determine the strength and capacity of the tire. It can be quite essential to compare the tire size comparison to choose a tire for your personal requirements.

Tire Width:

The tire dimensions of the width refer to the measurement from one sidewall to another. The tire width conversion of the “P225” is for a passenger vehicle and it has a nominal width of 225 millimeters. You can choose the width of the tire by tire calculator which makes your purchasing more reliable and choosing the width of the tire for your vehicle becomes easy.

Tire Diameter:

The tire diameter is the height of the rim from the top to the bottom and it is the tire best set at the top to the bottom of the tire.  Now for the code of  P225/70R16, 91S would fit a rim with a 16-inch diameter. For a precise estimation of the tire diameter in standard and metric units, use the tire size calculator and get diameter calculations in moments.

Wheel Diameter:

The Wheel or rim diameter is the actual distance calculated in inches across the face of the wheel or the size of the rim.  The wheel diameter or the tire dimensions are described in the code after the letter that indicates the internal construction of the tire. The tire calculator ensures you get the perfect tire fitment for your vehicle and rims without any guesswork.

Section Height:

It is the height of the tire measured from the rim to the outer edge of the tire of the vehicle.  The section width of the tire dimensions is the sidewall to sidewall of a tire. A tire code xxx/65 represents that the section height of the tire is 65% of the width of the tire. You can choose a tire from a range of tire circumference calculators, making your choice more precise. Regardless of the vehicle you drive, our tire comparison calculator assists you to compare differences. These tires involve high-performance sports cars full-sized trucks and SUVs. Our tire calculator can compare the tires of any make or model from major auto manufacturers.

How to Read the Tire Code?

There are certain tire conversions included in the tire code:   Image For Read the Tire Code

The Intend of Use: 

The first portion of the code is made up of 1 or 2 letters (P, LT, ST, T) and defines the type of vehicle that the tire is intended to be used to.  There are 4 vehicle classes:
  • P stands for a passenger car. 
  • LT stands for a light truck. 
  • ST stands for a special trailer. 
  • T stands for temporary. 
Our tire size conversion calculator will assist you find the difference in external dimensions of the wheels, height clearance, revolutions per mile, and other characteristics and capacities of the tires. This is essential when installing tires of other sizes on your vehicle

Nominal Section:

The first number of the tire code is the width in millimeters. You need to divide this number by 25.4 to get the inch equivalent as there is 25.4 mm 1 inch of the tire measurements. In this case, the 285/75/R16,  the 285 is the width of the tire. The number preceded by R is the aspect ratio of the tire. And the number after the tire is the diameter of the tire.

Internal Construction:

The letter (B, D, and R) indicates the internal construction of the tire. The internal structure of the tire is responsible for the strength and durability of a tire. 
  • R stands for radial. 
  • D stands for diagonal.
  • B indicates a bias-belted tire

Load Index or the Capacity: 

The number before the “H” is the load index or the capacity of the load the tire can bear.

The Speed Rating:

The last alphanumeric parts indicate the speed rating, in this case, it is “H”, “M” etc. 

US DOT Code:

The DOT code is a code in the USA for the company, factory, batch, mold, and date of production of the tire.

Working of the Tire Size Calculator:

For converting the tire dimensions with a tire conversion calculator, you need to follow the steps: Input:
  • Choose the appropriate option
  • Enter the tire specification
  • Hit the calculate 
  • Diameter of tires dimensions
  • Width of tire
  • Sidewall of tire
  • Circumference  of tire
  • Mileage of the tire

Tire Conversion Chart:

The tire conversion chart for the tires and their specifics are given in the table. You can adjust and find more possibilities and choices in metric tires with the tiresize calculator. You can adjust tire conversion relative to your own specific requirements.
Tire Size Diameter Rim (H x W)
285/70R18 33.7″ (+3%) 18″ x 7.5-9.5″
305/65R18 33.6″ (+2.7%) 18″ x 8.5-11.0″
285/60R20 33.5″ (+2.4%) 20″ x 8.0-10.0″
295/75R16 33.4″ (+2.1%) 16″ x 7.5-9.5″
315/70R16 33.4″ (+2.1%) 16″ x 8.5-10.0″
325/60R18 33.4″ (+2.1%) 18″ x 8.5-10.0″
295/70R17 33.3″ (+1.8%) 17″ x 8.0-9.5″
375/45R20 33.3″ (+1.8%) 20″ x n/a
275/70R18 33.2″ (+1.5%) 18″ x 7.0-8.5″
305/55R20 33.2″ (+1.5%) 20″ x 8.5-10.0″
255/85R16 33.1″ (+1.2%) 16″ x 6.5-8.0″
255/80R17 33.1″ (+1.2%) 17″ x 6.5-8.5″
295/65R18 33.1″ (+1.2%) 18″ x 8.0-10.0″
275/60R20 33″ (+0.9%) 20″ x 7.5-9.5″
245/70R19.5 33″ (+0.9%) 19.5″ x n/a
285/75R16 32.8″ (+0.3%) 16″ x 7.5-9.0″
305/70R16 32.8″ (+0.3%) 16″ x 8.0-9.5″
375/50R18 32.8″ (+0.3%) 18″ x n/a
295/55R20 32.8″ (+0.3%) 20″ x 8.0-10.0″
325/50R20 32.8″ (+0.3%) 20″ x 9.0-11.5″
265/80R16 32.7″ (Equal) 16″ x n/a
235/85R17 32.7″ (Equal) 17″ x 6.0-8.0″
305/65R17 32.6″ (-0.3%) 17″ x 8.5-11.0″
265/70R18 32.6″ (-0.3%) 18″ x 7.0-9.0″
285/65R18 32.6″ (-0.3%) 18″ x 8.0-10.0″
245/75R18 32.5″ (-0.6%) 18″ x 6.5-8.0″
265/60R20 32.5″ (-0.6%) 20″ x 7.5-9.5″
305/60R18 32.4″ (-0.9%) 18″ x 8.5-11.0″
315/50R20 32.4″ (-0.9%) 20″ x 8.5-11.0″
285/55R20 32.3″ (-1.2%) 20″ x 8.0-10.0″
375/55R16 32.2″ (-1.6%) 16″ x n/a
275/70R17 32.2″ (-1.6%) 17″ x 7.0-8.5″
255/75R17 32.1″ (-1.9%) 17″ x 6.5-8.5″
255/70R18 32.1″ (-1.9%) 18″ x 6.5-8.5″
275/65R18 32.1″ (-1.9%) 18″ x 7.5-9.5″
255/65R19 32.1″ (-1.9%) 19″ x 7.0-9.0″
255/60R20 32″ (-2.2%) 20″ x 7.0-9.0″
305/50R20 32″ (-2.2%) 20″ x 8.5-11.0″
225/90R16 31.9″ (-2.5%) 16″ x n/a
345/55R17 31.9″ (-2.5%) 17″ x n/a
235/75R18 31.9″ (-2.5%) 18″ x n/a
275/55R20 31.9″ (-2.5%) 20″ x 7.5-9.5″
225/70R19.5 31.9″ (-2.5%) 19.5″ x n/a
235/80R17 31.8″ (-2.8%) 17″ x 6.0-7.5″
The tire size comparison calculator instantly displays the difference between tire size chart comparisons in the table. This enables the user to compare the various tire size calculations and to know their respective strength and capacity.


From the source of Wikipedia: Tire code, Tire Conversion From the source of Tire aspect ratio, Tire ratio
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