Tire Translating: How to Read and Understand Your Car or Truck’s Tire Codes

How To Read Car Tires

At first glance, looking at a tire and attempting to understand the markings can seem overwhelming. There are a lot of numbers and letters on the sidewalls of vehicle tires, but these each have a significant meaning.

Whether you drive a hybrid sedan, a compact Smart Car, love Honda crossovers, or have a penchant for Ram trucks, all of these vehicles will have markings to denote various statistics about their tires. Having this information can tell you not only when your tires were made, but also other beneficial details such as how fast your tires can safely go and what kind of payload they can handle.

Tire Class

The first letter you will see when looking at the series of numbers and letters will designate the type of tire class. Think of this as the kind of vehicle for which the tire is meant. On most automobiles, you will see a P, which stands for a passenger vehicle. These are made for not only smaller cars but also many vans, pickup trucks, and SUVs.

Motorcycle tires will have the letter M instead of P, for motorcycle rather than a passenger vehicle. If you see an LT, this designates a tire for a light truck. Light trucks are specified as vehicles that can tow trailers with a ¾-ton to 1-ton capacity.

If the first two letters are ST, this means “special trailer,” or trailers with a fifth wheel, as well as other types such as boat trailers. European tires have no letter at the beginning as these are metric tires.

Section Width

The second part of a tire reading, a number, will specify the section width of your tread. This measurement is the width of your tires, measured from one side wall to the other, from bead to bead, and designated in millimeters. For instance, 215 means you have a width of 215 mm.

Aspect Ratio

The third designation is the aspect ratio of the tire, or how high or tall the sidewall of your tire is. This measurement is occasionally referred to as the profile of your tires. There is a slash to designate the percentage of the section width, such as 55, or 55 percent of the 215 mm.

Construction Type

A single letter following the aspect ratio designates the construction type of your tire. This indicates the interior, such as radial tires, bias construction, and so forth. If you see the letter R, that means you have radial tires. D is for a tire builds with a diagonal ply. Diagonal-ply tires are also called bias, conventional, or cross-ply tires.

Wheel Diameter

After your construction type letter, you will find another number that indicates your wheel diameter. This number simply states the measurement of the diameter of your wheels in inches or the width across the center. This can be helpful to know to understand what size tires you need to fit on your specific wheels.

Having the incorrect size tire can be a problem that poses safety issues, so make sure your tires are the exact size designed for your automobile. Incorrect sizing can rub on the body of the vehicle, wear down by chaffing on the suspension, pull at the steering, or result in a rigid, bumpy ride.

Load Index

The next number will be your load index. Both load index and speed ratings have numerous designations that do not necessarily correspond with the number on the tire. For example, a load index of 77 has a capacity of 908 pounds. A load index written as 140 has a load capacity of 5,512. Searching load index charts is helpful if you need this information since the numbers do not intuitively correspond to the average person.

Speed Rating

Finally, you have your speed rating denoted with the final letter. A speed rating on any tire tells you the highest speed you can travel safely on those tires. Even if your vehicle has a top speed above your tires—which is rare—driving faster than the speed rating on your tires poses an extreme danger.

Never drive faster than the speed rating of your tires. Many speed rating charts are available if you are curious about your specific tires. Not only is it perilous, but tickets can also negatively affect your insurance rates.

Tire Costs

Just as the cost of different types of a vehicle varies significantly, the price of tires does, also. Luxury, new car prices will be higher than, say, used truck prices built 10 years ago. Tires are similar—you can get premium quality all-season or snow tires, or pick the most economical set, so an exact price is hard to nail down.

You can at least go in with a broad idea of prices in mind, though. A set of four tires being installed on a typical car in the mid-price range will generally have a price tag anywhere between $500 on the lower end and $750 on the higher end. So, the average set of new tires for a vehicle runs around $600 to $650 for four tires.

If you opt for something such as all-season tires, they will range between $50 and $200 per tire. On many SUVs or pickup trucks, tire prices will generally be a bit more.

For luxury and sports cars, tires can be significantly higher in price. High-performance tires for these types of vehicles can run anywhere from $150 to $1,500 per tire. Just another reminder of the ongoing maintenance costs of expensive luxury vehicles. Even your tires can run in the thousands when they need to be replaced.

DOT Label

If you search your tire, you will also see the phrase DOT with a combination of letters or numbers after it. The DOT labeling stands for the Department of Transportation and all tires in the United States are required to have this marking, as well as past the safety standards to be registered. The specific code indicates the manufacturer as well as the plant at which your tires were made.

There will also be a date indicated by the week of the year and the year itself that your tires were produced. This date is at the end of the DOT code and will be four numbers. For example, if your tires were made in the 12th week of 2019, it would read 1219.

Knowing where to find your DOT registration on your tires can be vital when it comes to recalls. Sometimes it is easy to ignore recalls, but tire safety affects yourself, your family, and others on the road. There have been historically significant recalls on tires, such as the Firestone/Bridgestone recall back in 2000. Dozens of deaths resulted in that particular recall, so it is smart to know where to look on your tires just in case future recalls arise.

Knowing Your Tires

You can check more on your specific vehicle’s specifications by looking up their vehicle history report. Having more knowledge about your automobile can never hurt and will help you walk into a tire shop with more confidence next time you need a tire rotation or a new set of rubber for the road.

Understanding all of the designations on your tires can also be beneficial when searching to buy tires, as you will know precisely what you are looking for regarding size, measurements, payloads, and speed ratings for your vehicle. Just be sure always to purchase your tires from a reputable or reliable source.