How To Read The Size Of A Tire

Tires June 14, 2021

What Exercise the Numbers on My Tires Mean? How to Read Tire Sizes

Existence able to quickly glance at the sidewall of your tire and determine the tire size your specific vehicle needs can relieve you time, trouble and money. Even withal, non many people know how to really read a tire size even though it's printed right in that location on the sidewall. As a mix of messages and numbers, information technology's not as like shooting fish in a barrel to read every bit finding a size 9 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 correct tire size is necessary.

Your tires support the entire weight of your vehicle and are the only parts of your car that really brand contact with the road. Making sure that you select the proper tire size when it's time to store for new tires is critical to the health of your tires and vehicle.

A tire's task is to conduct your vehicle and guide it where information technology needs to go, so when a tire is too big or too small, not only is performance hindered just your safety is too put at take chances. Your tires demand to be broad, potent and thick enough to carry the weight of your vehicle while nevertheless existence able to plough and motion. Scratching along the sides or getting caught while trying to turn could cause serious damage to your tires, forcing you to supervene upon them much sooner than you'd otherwise need.

What Practise the Numbers on My Tires Hateful?

Looking at tire size for the showtime time tin experience like reading a foreign language, but in one case you learn how to break down what each section of the tire size means, you'll notice 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 mutual blazon of tire. "LT" (lite trucks that carry heavy loads) is some other mutual tire type designation that you'll likely run into. Other tire types include "T" (temporary), "ST" (trailer) and "C" (commercial). If at that place 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/Profile

Aspect ratio refers to the relationship between the tire'southward sidewall height and the tire'southward width in the grade of a percentage. Sidewall height can be determined by measuring the distance between the edge of the rim and the summit of the tire at the edge of the tread. Aspect ratio translates to how well your vehicle can handle the tire. The higher the aspect ratio, the longer it takes for your tire to respond to a turning command, making lower attribute tires often easier to command.

Construction Blazon

This refers to how the tire was constructed. Typically, you lot'll only run across "R" for "radial tire" since that is the nearly common type of tire produced nowadays. Radial tires are constructed past assembling piles perpendicular to the direction that they travel, allowing for a smoother ride, longer tread life and reduced fuel production.

Wheel Size/Rim Diameter

Measured across the center of the tire from one end to the other, cycle size refers to the bore of your wheel and is typically measured in inches. Overall bike size is often indicated by the rim bore every bit a autograph for what size tire your vehicle needs.

Load Index

Load index is a autograph way of describing the total weight that the tire can handle when it is fully inflated. The college the load index rating, the more weight the tire can carry. You need a tire load index rating chart to see how your load index rating correlates to the weight the tire can carry. For case, a load alphabetize of 81 means that the tire tin carry up to 1,019 pounds. Load index ratings for the average vehicle range from 75-100, simply some tires can range all the manner upwardly to 150, which equates to 7,385 pounds.

Speed Rating

Similar load alphabetize, speed rating is some other shorthand way to reference how fast the tire is designed to go. It is indicated past a letter that corresponds to the maximum speed of the tire. For example, a speed rating of "T" ways that the tire is designed to get up to 118 miles per 60 minutes.

Read: A Guide to Tire Load Index & Speed Ratings

How to Read Tire Sizes

Breaking downward a tire size measurement into its individual parts makes it easy to read once you're in the know. Now that you know what each element of tire size means, nosotros tin 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 rider tire, one of the most common types of tires.

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

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

R (Structure Type): Radial tire, the most mutual type of tire produced today.

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

103 (Load Index): A load index of 103 means this tire can carry upward 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 synthetic tire with a diameter of eighteen inches that tin acquit upwardly to 1,929 pounds and can go up to 130 mph.

We'll Help Y'all Decode All Your Tire Needs

If reading tire sizes all the same seems like a mystery, drop by your local Virginia Tire & Auto and let our tire experts walk y'all through the procedure. We'll help you notice the exact tire your vehicle needs. Schedule an date online or phone call 855.425.3677 to talk to a tire proficient.