How to find a tyre size

For the safety and overall performance of a vehicle, it is important to install right Tyres. If you want to buy a Tyre for your vehicle, the first thing you have to do is to locate the right Tyre size.

There are many things like width and diameter, load index and speed rating etc, which are integral in order to find the correct Tyres.


How to determine the correct Tyre size for your vehicle is not as tough as it seems, in fact it is very simple. If you already know your Tyre size, then it is easy to choose right Tyre but if you don’t know then, all the information you need is available either in the “Owner’s Manual” for your vehicle or somewhere within the vehicle itself.

If In a case, you can’t locate the manual; you can easily check Tyre fit guide in these locations:

  • The driver’s side door jamb
  • Inside your glove box door
  • Within your gas tank hatch







On the sidewall of the Tyres, Tyre size data is available. Let’s take a look what all those numbers and letters mean.








As shown in the above image, One by one, in the order, Tyre data appears in your Tyre. The above image will be used as an example to discuss in detail to facilitate you about Tyre data.


P225/70R16 91S

"P" designation means that it is a passenger car Tyre. This “Signifies that the Tyre is designed to primarily be used on passenger vehicles; passenger vehicles can not only include cars but also minivans, SUV’s, and other light duty pickup trucks. This “P” is a short for “P-metric”.

And on the other hand "LT" designation is meant for a light truck. Light truck Tyres are designed to be used on vehicles which are capable of carrying heavy cargo or pulling trailers“LT” is short for “LT-metric”.


P225/70R16 91S

Tyre width is the width which is always referred to the measurement from one sidewall to other sidewall. The very first number which appears in your Tyre size information is the width. Thus, a Tyre with the measurement of “P225” is for a passenger vehicle and which has a nominal width of 225 millimeters.

Aspect Ratio

P225/70R16 91S

Aspect ratio comes right after the slash mark; itis actually the ratio of the height of the Tyre cross-section to its width. In percentages Aspect ratios are always delivered. Tyre makers calculate the aspect ratio by dividing a Tyre height off the rim by its width. If a Tyre has an aspect ratio of 70, it means the Tyre height is 70% of its width.


P225/70R16 91S

Construction comes after the aspect ratio; Construction indicates you how the layers of the Tyre were put together,there are two types of construction that you may see on the sidewall of a Tyre:

R– Radial

D– Diagonal or Bias Ply

TheRin P225/70R16 91S identifies that the Tyre has aRadial construction in which the Tyre's body plies "radiate" out from the imaginary center of the wheel. Radial Tyres have become the most popular type of Tyre today representing over 98% of all Tyres sold.

On the other hand, if theRin the size is replaced with aD(P225/70D16 91S), it identifies that the internal Tyre body plies crisscross on aDiagonal and that the Tyre has a "bias ply" construction. Tyres using this construction are used for light truck and spare Tyre applications.

If theRin the size is replaced with aB(P225/70B16 91S), it would identify that the Tyre body plies not only crisscross the Tyre on a diagonal as before, but that they are reinforced with belts under the tread area. This type of Tyre construction is called "Belted." practically extinction has occurred on these Tyres.

Load Index

P225/70R16 91S

The next figure in the sequence is your Tyre’s load index, Load index is an assigned number that corresponds with the load-carrying capacity of a Tyre. In other words, how much weight, the Tyre can support when fully inflated. It is vital that you check with your manufacturer what capacity should be put on your Tyre.

Speed Rating

P225/70R16 91S

The final figure in a Tyre size sequence is the speed rating.The speed symbol is made up of a single letter or an A with one number. It indicates the maximum speed at which the Tyre can carry a load corresponding to its Load Index.

Maximum service speed for a Tyre is indicated through Speed rating. Speed rating letter directly corresponds to a particular speed capability which is strictly based on a standardized laboratory test. A speed rating isn't, a recommendation to exceed over speed limits, and it also doesn't indicate how well a Tyre handles or corners. Tyres with higher the speed ratings, usually tend to offer increasing handling performance. It is must to have replacement Tyres the same or higher speed rating to maintain vehicle’s speed capability.

Below is a list of speed ratings along with the corresponding speeds they represent. Important to remember that speed ratings apply only to the Tyre itself, and not to a particular vehicle.

  • B - Up to 31 mph
  • C - Up to 37 mph
  • D - Up to 40 mph
  • E - Up to 43 mph
  • F - Up to 50 mph
  • G - Up to 56 mph
  • J - Up to 62 mph
  • K - Up to 68 mph
  • L - Up to 75 mph
  • M - Up to 81 mph
  • N - Up to 87 mph
  • P - Up to 94 mph
  • Q - Up to 100 mph
  • R - Up to 106 mph
  • S - Up to 112 mph
  • T - Up to 118 mph
  • U - Up to 124 mph
  • H - Up to 130 mph
  • V - Up to 149 mph
  • W - Up to 168 mph
  • Y - Up to 186 mph
  • Z - 149 mph and over

If a listed speed rating contains two letters (such as VR), the first letter represents the speed rating and the second letter (R) indicates that it is a radial Tyre