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Shopping for new tires and unsure how to find the tire size for your vehicle? Wondering, “What tire size do I need anyway?” The team at the Mercedes-Benz of Chicago tire center will show you how to find the tire size on your Mercedes-Benz tires, and how to read the tire size so you get the tires you need for your Mercedes-Benz!

What do Tire Sizes Mean for Choosing a Tire?

When it comes to choosing a tire for your Mercedes-Benz, it needs to be the right size to support your vehicle. See the size indicated on a tire sidewall to find out what type of vehicle it’s made to support. Here, you’ll see information including wheel size to maximum pounds the tire is capable of carrying. If you still have questions about how to tell tire sizes apart and choosing the best model for your vehicle, reach out to the Mercedes-Benz of Chicago tire center.

How to Tell Tire Sizes: Meaning of the Markings

At first glance the markings on your sidewall may not seem to mean much, but if you know how to read tire sizes and markings, you’ll see they actually tell a lot about your tire-including size, construction, and capabilities. Compare you’re sidewall to our guide below: 

Tire Type

The first thing you’ll see indicated on your tire is the tire type. “P” shows your tire is for a passenger, “LT” is the code for light trucks, and an absence of lettering indicates Euro metric tires. 

Tire Width

A three-digit number will follow the tire type, and indicate the tire width. This width is measured from one sidewall to the other in millimeters. 

Aspect Ratio

Next up is the aspect ratio, which is the ratio of the height of the tire’s cross-section to its width. This will be denoted by a two digit number. 


Aspect ratio numbers will be followed by a letter which indicates the tire construction. Tires are created using layers of fabric, and the most common tire type is a radial tire. Radial tires are constructed in a way that improves performance and are noted by the letter “R” on the sidewall. 

Wheel Diameter

If you’ve been wondering, “What size tires do I need,”– wheel diameter will tell you. The wheel diameter shows the measurement in inches of the wheel a tire will fit. In order to find a tire that fits a 20-inch wheel, you’ll need to choose a tire with a number “20” in this spot. 

Load Index

The load index is the maximum load a tire can carry while properly inflated and is found after the wheel diameter on the sidewall. To make sure your tire can meet the demands of your vehicle, you’ll need a tire with a load index that meets or exceeds the specifications set by your vehicle’s manufacturer.

Speed Rating

Speed rating of your tire is up next, and is not to be confused with the speed capabilities of your vehicle. “Q” rated tires can reach a top speed of 99 mph, while “(Y)” tires rating are built for speeds above 186 mph. No matter what your tire is rated for, you’ll still need to keep to posted speed limits. 

More Tire Markings & Codes

You know the basics on how to read tires sizes, but there are other tire markings that you may be wondering about. Some of these additional markings that you may find on your vehicle include:

DOT Symbol

For tires to be sold in the U.S., they must meet the minimum standards of the Department of Transportation. Tires that have passed this required testing will be marked with “DOT.” This will be followed by a letter and number which show which plant the tire was manufactured at, as well as two more letters indicating the tire size.

Tire Identification Number

After the required “DOT” symbol, there may be some optional markings. These will be a series of letters and numbers, and may be included by the manufacturer to share information about the tire tread, construction, and the week and year the tire was fabricated 


Uniform Tire Quality Grading, or UTQG for short, is a rating system that has been developed to grade tires based on tread wear, traction, and temperature resistance. This system was created by the U.S. Department of Transportation and has ratings running from AA to C for temperature and A to C for traction. C is the lowest ranking on the UTQG scale. Testing for these ratings are conducted by the manufacturer and indicate tire durability, not necessarily tire lifespan. 

Maximum Tire Pressure & Load

The next set of numbers that proceed the letters” PSI” indicate the maximum amount of tire pressure the tire can hold and operate with. The following numbers before “LBS”show the maximum load in pounds that a tire can carry while the tires are at their maximum inflation. Neither of these numbers tell what should be maintained for ideal performance. Those suggestions can be found in your owner’s manual. 

What Size Tires Do I Need for My Mercedes-Benz?

You know how to read tire sizes, and can answer the question, “What do tire sizes mean,”, but how do you find the recommended tire size for your Mercedes-Benz? Mercedes-Benz of Chicago technicians can help find the tires you need, or you can check your owner’s manual.

Shop Mercedes-Benz Tires in Cook County!

If you’re in Chicagoland and looking for help with size and replacing your Mercedes-Benz tires, you can count on our expert Mercedes-Benz technicians. Contact us today with questions about how to read your tires sizes, or bring your vehicle in for tire replacements today!


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