Whether you drive a sedan or a truck, having the right sized tires is something you can’t cut corners with. When buying a new tire, checking the tire sidewall reveals a code that tells you more than you would think the product. It means little unless you understand how each product trait pertains to your vehicle. In this tire buying guide, we will start with the various criteria that differentiate every type of tire.


The information that you need to know includes:


Finding the Right Type


P-Metric tires are generally used for passenger vehicles in the U.S. The tire code will start with a “P” if it is this type. If not, then it is a Euro-Metric tire. The two types have different load capacities, while “LT” refers to a tire designed for light trucks, which usually require a higher inflation pressure.


Tire Size


The size of a tire is defined by several measurements, including:


  • Width: Tire width is measured from one sidewall to another (at the widest point), in millimeters. It is indicated directly after the initial letter code to indicate, for example, a width of 215 millimeters or other value.


  • Aspect Ratio: Indicated by a two-digit number, this compares the height of the cross section to the width of the tire. For example, if the value is 65, this means the height equals a value that is 65% of the tire’s width. Sedans and SUVs have aspect ratios from 45 to 60, while low-profile tires run from 30 to 40.


  • Construction: If an “R” is included next, this indicates the product is a radial tire, which means its layers run radially across the structure. Most modern tires are radial.


  • Wheel Diameter: Reveals what sized wheel the tire is designed for. Representing the size of a wheel from end to end, it may be represented by a label such as R15 (meaning the tire is designed to fit a 15-inch diameter wheel).


Other Ratings


Additional traits you need to know about when buying a new tire include:


  • Load Index: The maximum load, in both pounds and kilograms, can be found on the sidewall. It shows the peak load that the tire can support when it is fully and properly inflated.


  • Speed Rating: The maximum speed of the tire is indicated by its speed rating; it usually matches the top speed of the vehicle it’s intended for. Letters go from L to Y. These span maximum vehicle speeds from 75 to 186 mph.


  • UTQG: The Uniform Tire Quality Grading informs consumers about tires’ relative treadwear, traction, and temperature capabilities. A letter grading system, developed by the U.S. Department of Transportation, identifies where the tire stands in these categories.


Other important indications on the sidewall include the letters “DOT”, which indicate the tire is in compliance with the Federal Motor Vehicle Safety Standards, and the Tire Identification Number (TIN) that represents where and when the tire was made.


The tire’s tread-wear rating is a number; the higher it is, the longer the it is likely to last. However, this is just a rough estimate. The tire mileage/tread-wear warranty can give you a general idea of how long the tire might last.


Truck Tire Sizes


Light Truck tires are suited for vehicles that haul heavy loads or tow other vehicles. A standard LT tire can support up to 1 ton of towing capacity. The designation “XL” means “Extra Load”, which means the tire can support a higher weight/load than an “SL” (Standard Load) tire. Designed for trailers, “ST” (Special Trailer) tires can handle heavy loads but are not suited for use on trucks or vehicles other than trailers.


Choose Wisely


Whether you choose to replace or upgrade the tires on your vehicle, or invest in all-season, summer, or winter tires, it’s important to consider the size first. The ones you install must support the weight of the vehicle, any towing loads, and driving conditions such as inclement weather or rough roads. It’s best to avoid guesswork. Instead, consult with the owner’s manual, manufacturer, or dealer about the best tire options for your sedan or truck.


Visit Hawthorne Auto Square


As a buy here, pay here car dealership, we can set you up with one of a wide range of high-quality, pre-owned vehicles from top brands. Our full inventory is available online. You can pick out a car in-person or online and take advantage of our specials and exclusive financing options. Service and maintenance are included in our 6-month comprehensive warranty. Visit our dealership or call 866-707-7664 to learn more.