How to find your Tire Size

October 2nd, 2016

If you’re in the market for new tires, one of the first things you’ll need to do is identify the correct tire size for your car. In fact, choosing the wrong tires for your car could impact optimal vehicle performance and safety. Fortunately, it’s rather simple to identify what tire size you need. Your car’s original tire size can be found in the owner’s manual and on the vehicle's tire information placard (located on the driver's side door jamb), but you can also check your current tire’s sidewall. The sidewalls of your tires provide information about your tires dimensions, load index and operational purpose. 

 

The markings on your tires can be broken down to understand your tires size and features. 

 

Let’s break a popular passenger tire size down to find out what those letters and numbers mean: 

P235/70R16 90H

 

The “P” stands for passenger so these tires are often called P-Metric. 

Other letters you might see in this area include:

LT: Light Truck

ST: Special Trailer

T: Temporary (spare tire)

NO letter at the beginning of the size description indicates that the tire is Euro-Metric. The biggest difference in a Euro-Metric tire is the difference in load carrying capacities. 

“235” represents the width of the tire from sidewall to sidewall.  The larger the number, the wider the tire

 

“70” is the aspect ratio. This is the official sidewall height shown as a percentage of section width.  So the sidewall height on this tire is 70% of 235 or about 164.5 millimeters

 

“R” is the radial construction. This is the industry standard for passenger car and truck tires

“16” means this tire is designed to fit on a rim with a 16 inch diameter

This number is important if you plan on upgrading your wheel size. If your wheel diameter changes, you’ll have to purchase a new set of tires that match the new diameter

“90” is the tires load index. It is a measurement of how much weight each tire can support. “90” indicates a maximum weight of 1,323 pounds per tire. Be sure you multiple your load carrying capacity by 4 to get the total capacity for a complete set of tires

 

This number can vary but each number can be found on the Load Carrying Capacity Per Tire Chart below.

“H” measures the speed rating.  “H” signifies that this tire can safely drive up to 130 mph for an extended amount of time.

 

Again, this value along with the associated definition can vary so please consult the Speed Rating Chart below.

 

We hope you find this information helpful. If you need any assistance or have questions about your tire size, we welcome you to call 334-298-8476 for help.

  Tags: new tires
  Posted in: Tires 101