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How to Read Tire Size

Are you in need of new tires for your Mercedes-Benz and wondering, “What do tire sizes mean exactly?” Tire sizes help you pick the right tire to support the needs of your vehicle. Deciphering your tire size based on your tire’s markings may seem like reading another language, but Fletcher Jones Imports’ guide to how to find tire sizes will help you understand your tire markings and choose the right size replacement for your vehicle! 

Learning How to Tell Tire Sizes

tiresOne look at the sidewall of your tire will show a string of letters and numbers that represent different aspects of your tire construction and size. These markings can be understood using our breakdown below: 

Tire Type

The class of the tire is indicated by the very first letter. An “LT” indicates the tire is rated for light trucks, a “P” means the tire is for a passenger vehicle, and no letters mean that this is a Euro metric tire. 

Tire Width

After the tire class, you’ll find a three-digit number. This number is the width of the tire in millimeters as measured from one sidewall to another. So if you see “P245/” on your tire, that means you have a passenger vehicle with a tire width of 245 millimeters. 

Aspect Ratio

The aspect ratio is represented by a two-digit number following the tire width and slash mark. This is the ratio of the height of the tire’s cross-section to its width. 


Following the aspect ratio is a letter that denotes the construction of the tire. Indicated by the letter “R,” the most common tire is a radial tire. This type of tire is built with layers of fabric with cords that run at right angles to the circumference of the tire. This method of construction reinforces the tire tread for increased strength and performance. 

Wheel Diameter

Wheel diameter is the next two-digit number and specifies the measurement in inches of the wheel a tire will fit, so the number “19” means your tire will fit a 19-inch wheel. 

Load Index

This number represents the maximum load this tire can carry while properly inflated and is found after the wheel diameter. When choosing a tire, you need to make sure your tire load index meets or exceeds the specifications set by your vehicle’s manufacturer.

Speed Rating

Past the load index number, you’ll find another letter which represents the speed rating of the vehicle. “Q” rated tires with a top speed of 99 mph are where speed ratings typically start, and speed ratings end with “(Y)” which denotes tires built for speeds above 186 mph. No matter what your tires are rated for, you need to consider road conditions and obey posted speed limit signs while driving. 

Other Tire Codes & Markings

Beyond tire size and construction, you’ll find other tire markings and optional codes on your sidewall. These symbols can include: 

DOT Symbol

The letters “DOT” stand for the Department of Transportation and are a required marking to show that the tire has passed all the minimum DOT standards to be sold in the U.S. Succeeding this, another letter and number will note the plant the tire was manufactured at, as well as two more letters indicating the size. 

Tire Identification Number

Following the “DOT” symbol, there may be an optional marking consisting of a series of letters and numbers. Some manufacturers include this to note things like tire tread, construction, and the week and year the tire was produced. 


UTQG, or Uniform Tire Quality Grading, is a system that rates tires based on tread wear, traction, and temperature resistance. Developed by the U.S. Department of Transportation, ratings run from A to C for traction and AA to C for temperature, with C indicating a lower ranking. Keep in mind these rating tests are performed by the manufacturer and rate durability, not the projected lifespan of the tire. 

Maximum Tire Pressure & Load

To find the maximum amount of tire pressure the tire can hold and operate with, look for a number followed by the letters “PSI.” The maximum load in pounds that a tire can carry when the tires are at maximum inflation is indicated by a number followed by “LBS.” It’s important to note that these are true maximums, not the pressure or load that’s recommended for optimal vehicle performance. To find your ideal tire pressure and load capacity, you’ll want to reference your owner’s manual. 

What Size Tires Do I Need?

You may be able to read your tire size, but that doesn’t answer the question, “What size tires do I need?” To find the correct tire size for your vehicle, you can check your owner’s manual. Or, if you want to have the professionals take a look, you can bring it to the Fletcher Jones Imports tire center, and our Mercedes-Benz techs will find you the ideal tire for your vehicle. 

Get Mercedes-Benz Tire Help at Fletcher Jones Imports!

Whether you want to find tires in the right size or have questions about tire maintenance or repairs, you can schedule a tire consultation at our dealership near Pahrump and Spring Valley. We have the approved tires for your Mercedes-Benz and offer service and parts specials!

View Our Tire Specials

Tire Inspection Special

Receive your Complimentary Tire Inspection, courtesy of Fletcher Jones Imports.

Proper tire maintenance is crucial to the performance of your Mercedes-Benz.

Must present offer when your service order is written for offer to apply. Valid at Fletcher Jones Imports. Mercedes-Benz vehicles only. Cannot be combined with any other offer or applied to past services. Does not include applicable taxes, shop supplies, and hazardous waste fees. Limit one original offer per person. Other restrictions may apply. Void where prohibited. See Dealer for details.

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Fletcher Jones Imports

7300 West Sahara Avenue Las Vegas, NV

Phone: (702) 364-2700


Phone: (702) 364-2700

7300 West Sahara Avenue Las Vegas, NV


Phone: (702) 364-2701

7300 West Sahara Avenue Las Vegas, NV
36.144889 -115.252885
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Fletcher Jones Imports
Fletcher Jones Imports
7300 West Sahara Avenue
Las Vegas, NV, 89117 United States
(702) 364-2700
Fletcher Jones Imports 36.144889, -115.252885.