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What Is a Tire Ply Rating?

A new tire is mounted to a wheel.

Are you planning on getting new tires? Or maybe you intend to use your vehicle to carry or tow a very heavy load and need to check them. In both cases, it’s essential to have an understanding of tire ply rating. Let’s examine what this rating is all about.

Definition and HistoryTire of car parked outside

Tire ply rating is a measurement that’s also referred to as tire load range. It tells you what type of load your vehicle’s tires can handle when inflated at the maximum recommended air pressure.

Many years ago, tires were made with several layers of cotton fabric. The term “ply rating” referred to how many layers — or plies — of cotton had been used to construct the tire. This rating was meant to indicate a tire’s strength. The higher the number of plies, the stronger the tire.

Today’s tires are no longer made of cotton. But just like the earliest examples, today’s ratings communicate a tire’s strength. They do this by referencing the tire’s load-carrying capacity.

If you’re planning to haul an unusually heavy load, it’s a good idea to check your tire ply rating to make sure your current tires are up for the task. Also, if you’re towing, check the trailer’s tires as well. And, if you’re planning on buying new tires for your vehicle, it’s vital that you make sure the ones you choose are rated to handle a weight that’s appropriate for your situation.

Where to Find It and How to Read It

A tire’s ply rating is located on its sidewall. Passenger tires come in three load ratings:

  • Light load. This is abbreviated as LL on the tire’s sidewall. LL tires can handle a maximum load pressure of 35 psi (pounds per square inch).
  • Standard load. Tires with a standard load rating either show SL or no letters at all on their sidewall. SL tires can handle a maximum load pressure of 35 psi. This type of tire is the most common variety offered.
  • Extra load. This is abbreviated as XL on the tire’s sidewall. These tires can accommodate a maximum load pressure of 41 psi.

LL and SL tires are meant for everyday driving. They aren’t built to withstand heavy loads.

XL tires are made with a reinforced internal structure, and they can handle heavier loads than SL tires of the same size.

Air pressure plays a role in how much weight a tire can carry. Tires that can hold higher air pressure can carry heavier loads. That’s one reason XL tires can handle more weight than those made for standard loads.

How to Choose the Right Tires

Here are some points to keep in mind when choosing tires:

  • Most cars use SL tires. If XL tires are needed, the owner’s manual will list this information.
  • You can replace SL tires with XL tires if you need rubber that’s equipped for heavier loads. However, if your car’s owner’s manual indicates that XL tires are required, stick to those and never switch — doing so could create a safety hazard.
  • XL tires aren’t used solely for carrying heavy loads. They’re also recommended for many high-performance vehicles.

Your tires facilitate safe driving, so make sure they are always properly inflated. Now that you know what tire ply rating is, you’ll be able to choose the best tires for your needs.

Check out all the tire products available on NAPA Online, or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on tire ply rating, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.

Photo courtesy of Unsplash.

Warren Clarke View All

I'm a writer and editor who's a regular contributor with the New York Daily News and Carfax, and my content has appeared in over 20 publications. I've written content that covers industries such as automotive, medical, insurance, healthcare, real estate, plumbing, pest control, dental and hospitality.

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