How to Read Your Tires: A Guide

The performance of a car is greatly influenced by the tires, which come in many categories that cater to different driving situations, such as off-road trips, grip in ice and snow, and the greatest road traction. Many consumers frequently know nothing more about their tires than the kind that came on the car or what the mechanic at the car dealership suggested. What you actually need to know about the type, tire size, and more are included in the string of letters and numbers on the side of your tires. Tire dimensions can be perplexing. On the sidewall, some of the numerals are stated in millimeters, while others are displayed in inches. The ideal size for your automobile, truck, or trailer may also vary based on where you drive and how you do it.

Your owner’s manual or the sign often found on the driver’s side door jam can both tell you what size original equipment tires you have. This is the size that the car’s manufacturer suggests. Understanding how to read your tires is an important skill to have and can make the tire-buying process simpler. Knowing the numbers can help you choose the right tire for your vehicle and driving circumstances. Understanding the significance of the letters and numbers on your tire’s sidewall will be simple with the help of a little explanation. The following explains what the symbols and numbers on the sidewall mean and how to interpret them:

Tire Type

The class of tire is indicated by the first letter of the code.

• P is for passenger car tires. P-class tires are usually suitable for automobiles, SUVs, crossovers, minivans, and compact pickup trucks.
• LT refers to a light truck tire, which is made for trucks and other vehicles with the capacity to tow trailers, haul heavy cargo, or just those that need a particularly robust tire. Three-quarter or one-ton vehicles and SUVs frequently have them.
• ST is an acronym that is short for Special Trailer. ST tire sizes are designed for trailers, such as utility and boat trailers, fifth wheels, and other types of travel trailers.

In rare instances, you might come upon a tire with just numbers and no letters. This indicates that the tire is a Euro-metric tire produced in accordance with European tire standards. These frequently have differing load indices than a tire of comparable P-metric size.

Tire Width

The string then continues with three numbers before the slash. This is the section width, which corresponds to the tread width of the tire. From one sidewall edge to the next across the tire, this is expressed in millimeters. Note that the three-digit number is bigger the wider the tire.

Aspect Ratio

The sidewall, or “profile,” of the tire will be higher or taller the larger the aspect ratio. The aspect ratio is shown as a percentage on the tire sidewall. It is the sidewall height represented as a percentage of tire width, calculated from the wheel rim to the top of the tread.

As an illustration, if the number next to the slash is 65, the aspect ratio is 65, which indicates that the sidewall is 65 percent as tall as the tire is wide. Take the tire width in mm and convert it to inches to get the sidewall height. After that, multiply it by 65%. (.65). This provides you with the sidewall height information in inches.

Construction Type

You may learn about the interior design of the tire from this one letter.

• R stands for radial tires, which are currently the industry standard for the majority of tires. They outperform earlier generations of tires in terms of traction on the road, rolling resistance for higher fuel economy, riding comfort, and endurance.
• D stands for bias-constructed tires, which are made of diagonal plies. Additionally, they go by the names conventional, x-ply, or cross-ply tires. This internal design is still used in some motorcycle and trailer tires.

An F followed by the kind of internal construction is sometimes used to identify some run-flat tires.

Wheel Diameter

The wheel diameter is indicated by this two-digit value in inches. A tire is securely sealed to a wheel in the space between the two bead seat regions.

Load Index

The tire load index is shown by the two- or three-digit figure that comes after the space. Based on the standard chart, the load index symbol indicates how much weight a tire can support. The figures in the load index pertain to weight capabilities of 99 to 7385 lbs. The load index has a starting value of 1 and a maximum value of 150. It is crucial to only use tires whose load index meets or exceeds the manufacturer’s suggested specification for your vehicle while having tires installed.

Speed Rating

The tire speed rating appears as the final letter. This shows the maximum speed that can be traveled without endangering yourself. When traveling at higher speeds, a tire with a higher speed rating will offer more control and handle heat better. The lowest speed rating of all the tires that are currently mounted on the vehicle is the maximum operational speed of the vehicle. Naturally, it’s best to always drive under the posted speed limit for safety. Typically, although not always, a speed rating is represented by one letter.

Lai’s Auto Service is Your Trusted Source for Tires & Tire Services

You should now be able to read your tires with confidence. The sidewall of your tire contains all of the pertinent details. But if you have any inquiries, Lai’s Auto Service’s experts are happy to assist. Our tire specialists in Saskatoon can address any concerns you may have and assist you in choosing the right tire type and size for your car and driving requirements.

You can depend on our knowledgeable mechanics whether you need to buy new tires or have extensive auto work done. Drivers have relied on our staff for years for vehicle maintenance, trustworthy auto repair, and unmatched customer service – all at the best and most competitive prices available. Contact us by phone at 306-652-4787.