How to read your tire size!

How Do I Read My Tire Size On My Sidewall?

The tire size branded on the sidewall provides a significant amount of information about the tire's intended purpose, dimensions, load capacity and high temperature/high speed durability.

Our primary example will be based on variations of the 225/50R16 size, although other sizes will appear where appropriate.

"The tire size branded on the sidewall provides a significant amount of information about the tire's intended purpose, dimensions, load capacity and high temperature/high speed durability."

How to identify the type of tire you have or the first letter of tire size from sidewall

Service Type

Most tire sizes begin with a letter or letters that identify the type of vehicle and/or type of service for which they were designed. The common indicators are as follows:

P = When a tire size begins with a "P," it signifies the tire is a "P-metric" size that was designed to be fitted on vehicles that are primarily used as passenger vehicles. If there isn't a letter preceding the three-digit numeric portion of a tire size, it signifies the tire is a "Metric" size (also called "Euro-metric" because these sizes originated in Europe).

HL = When a tire size begins with an “HL,” it will also end with an “XL.” This signifies the tire has higher load carrying capacity than an “XL” tire of the equivalent dimensions.

T = If a tire size begins with a "T," it signifies the tire is a "Temporary Spare" that was designed to be used temporarily only until a flat tire can be repaired or replaced.

LT = If a tire size begins with "LT," it signifies the tire is a "Light Truck-metric" size that was designed to be used on vehicles that are capable of carrying heavy cargo or towing large trailers.

LT = If a tire ends with "LT," it signifies the tire is a "Flotation" Light Truck size designed to be used on vehicles that are capable of carrying heavy cargo and towing trailers.

C = If a Euro-metric sized tire ends with a "C," it signifies the tire is a "Commercial" tire intended to be used on vans or delivery trucks that are capable of carrying heavy loads.

ST = If a tire size begins with "ST," it signifies the tire is a "Special Trailer Service" size that was designed to only be used on trailers.

How to identify the width of your tire from sidewall

Section Width

Following the letter(s) that identify the service type, the three-digit numeric portion identifies the tire's "Section Width" (cross section) in millimeters.

Sidewall Aspect Ratio

Following the three digits identifying the tire's Section Width in millimeters is a two-digit number that identifies the tire's profile or aspect ratio. This is the “height” of the sidewall, expressed as a percentage of the section width.

Internal Construction

A letter (R in this case) that identifies the tire's internal construction follows the two digits used to identify the aspect ratio.

R identifies that the tire has a Radial construction.

D identifies that the tire has a bias-ply (Diagonal) construction.

RF identifies that the tire has a self-supporting Run Flat construction.

How to identify your wheel diameter using the last numbers from sidewall

Tire and Wheel Diameter

P225/50R16 91S The 16 indicates the tire and wheel diameter designed to be matched together.

Service Description

P225/50R16 91S The 91S represents the tire's Service Description. A Service Description identifies the tire's Load Index (91) and Speed Rating (S).