The two-digit number after the slash mark in a tire size is the aspect ratio. For example, in a size P215/65 R15 tire, the 65 means that the height is equal to 65% of the tire's width. The bigger the aspect ratio, the bigger the tire's sidewall will be.
The first letter on a tire indicates the tire’s class. P designates this tire as a passenger car tire, an LT before the tire size would mean the tire is a light truck tire, and a European metric tire would have no letter before the tire size.
How to read tire size in inches is very straight forward. Example A : 33X12.50R15 The first number is your overall diameter of the tire. In this example the tire diameter or "height" is 33 inches tall.
This results in size designations such as 225/45RF17 91Y (for self-supporting run-flat tires that have a speed rating identified in their Service Description and 255/40ZRF20 (for Z-speed rated self-supporting run-flat tires in which the speed rating is contained in the tire size).
The load index and speed rating, or service description, are the numbers that follow the tire size. The load index tells you how much weight the tire can support when properly inflated. Load indices range from 75 - 105 for passenger tires, with each numeric value corresponding to a certain carrying capacity.
The tire size "P225/45R17 91V" may not mean much to the average person, but to tire geeks like us it speaks volumes. Read on to learn how to crack the tire code with this handy guide dedicated to tire types, sizes, and construction.
How To Read Your Tire Everything You Need To Know Is on the Sidewall. by Ronald Montoya. ... replace P-metric tires with equivalent-size Euro-metric ones because you gain load capacity that way.
A tire's dimensions can be determined by reading the markings on the sidewall. An example tire size is 245/45R18, which tells us the width, sidewall height, internal construction and matching wheel diameter.
Tire Type The letter "P" at the beginning of the "Tire Size" tells us the tire is a P-Metric tire, referring to tires made to certain standards within the United States, intended for Passenger vehicles.
Sidewall Inspection A tire’s sidewall is the thinnest area of your tire and is susceptible to many different kinds of damage. We recommend inspecting your tires regularly for damage of any kind.