What Do The Numbers On A Tire Size Mean

Tires June 14, 2021

What Do the Numbers on My Tires Hateful? How to Read Tire Sizes

Being able to quickly glance at the sidewall of your tire and determine the tire size your specific vehicle needs tin salvage you time, trouble and money. Even still, not many people know how to really read a tire size fifty-fifty though it's printed right at that place on the sidewall. As a mix of messages and numbers, information technology's not as easy to read as finding a size ix shoe.

Why Tire Size Matters

Other than the fact that tires need to physically fit on your vehicle, in that location are several reasons why having the right tire size is necessary.

Your tires support the entire weight of your vehicle and are the only parts of your car that actually make contact with the road. Making certain that you select the proper tire size when it's time to shop for new tires is critical to the wellness of your tires and vehicle.

A tire's task is to comport your vehicle and guide it where information technology needs to go, and so when a tire is too large or too small-scale, not only is functioning hindered but your safety is also put at risk. Your tires need to be broad, strong and thick plenty to behave the weight of your vehicle while yet being able to turn and move. Scratching forth the sides or getting defenseless while trying to plow could cause serious harm to your tires, forcing you to supersede them much sooner than you'd otherwise need.

What Do the Numbers on My Tires Mean?

Looking at tire size for the get-go fourth dimension tin can feel like reading a foreign language, but once you lot learn how to intermission down what each department of the tire size means, you'll detect they're not all that complicated.

Tire Type

Tire type refers to the service or type of vehicle that the tire was designed for. "P" stands for "passenger" and is the most common type of tire. "LT" (lite trucks that carry heavy loads) is another common tire blazon designation that you'll probable run into. Other tire types include "T" (temporary), "ST" (trailer) and "C" (commercial). If there is no letter, that usually indicates that the tire was manufactured in Europe for European cars. These types of tires are called metric or Euro-metric tires and are like in many ways to a passenger tire.

Tire Width

Measured in millimeters, this is the distance from sidewall to sidewall across the width of your tire.

Attribute Ratio/Contour

Aspect ratio refers to the relationship between the tire's sidewall height and the tire's width in the form of a pct. Sidewall top can be determined by measuring the distance between the edge of the rim and the elevation of the tire at the edge of the tread. Attribute ratio translates to how well your vehicle can handle the tire. The college the aspect ratio, the longer it takes for your tire to reply to a turning command, making lower aspect tires oft easier to control.

Construction Type

This refers to how the tire was constructed. Typically, you'll only see "R" for "radial tire" since that is the most mutual type of tire produced nowadays. Radial tires are constructed past assembling piles perpendicular to the management that they travel, assuasive for a smoother ride, longer tread life and reduced fuel product.

Wheel Size/Rim Bore

Measured beyond the middle of the tire from 1 finish to the other, bicycle size refers to the diameter of your wheel and is typically measured in inches. Overall wheel size is often indicated by the rim diameter as a shorthand for what size tire your vehicle needs.

Load Index

Load alphabetize is a shorthand way of describing the total weight that the tire tin can handle when it is fully inflated. The college the load index rating, the more weight the tire tin can carry. You need a tire load alphabetize rating chart to see how your load index rating correlates to the weight the tire can carry. For example, a load index of 81 means that the tire tin acquit upwardly to 1,019 pounds. Load index ratings for the average vehicle range from 75-100, but some tires can range all the way up to 150, which equates to seven,385 pounds.

Speed Rating

Like load index, speed rating is another autograph way to reference how fast the tire is designed to go. It is indicated by a alphabetic character that corresponds to the maximum speed of the tire. For example, a speed rating of "T" means that the tire is designed to go up to 118 miles per hour.

Read: A Guide to Tire Load Index & Speed Ratings

How to Read Tire Sizes

Breaking downwards a tire size measurement into its individual parts makes it easy to read in one case you're in the know. At present that yous know what each element of tire size means, we can walk through an case of how to read a tire size off of a sidewall.

Example: P255/45R18 103H

P (Tire Blazon): This tire is a passenger tire, one of the near mutual types of tires.

255 (Tire Width): The tire width is 255 millimeters from sidewall to sidewall (simply over x inches).

45 (Aspect Ratio): The tire's sidewall is 45% of the tire's width, which ways the sidewall is about 114 millimeters or just over 4 inches.

R (Structure Type): Radial tire, the nearly common type of tire produced today.

18 (Wheel Size/Rim Diameter): Going from edge to edge, the tire'due south bore is 18 inches across.

103 (Load Index): A load index of 103 means this tire can carry upwards to 1,929 lbs.

H (Speed Rating): A speed rating of "H" means that this tire is designed to withstand speeds up to 130 miles per hour.

In summary, a P255/45R18 103H tire would be a passenger tire with a width of 255 millimeters, a thickness or aspect ratio equal to 45% of the tire elevation which here is 114 millimeters. It is also a radially constructed tire with a diameter of eighteen inches that can conduct up to 1,929 pounds and can go up to 130 mph.

We'll Assist Yous Decode All Your Tire Needs

If reading tire sizes still seems like a mystery, drop by your local Virginia Tire & Automobile and allow our tire experts walk you through the process. We'll help you notice the exact tire your vehicle needs. Schedule an engagement online or call 855.425.3677 to talk to a tire practiced.