Tires come in all sizes and weight ranges. Differentiating between a 6-ply tire and an 8-ply tire might seem difficult at first but understanding what it means and how it applies to you and your car can change everything.
Tire ply is based on PSI (pounds per square inch of pressure), at its optimal fill of air. Every tire has several layers of tire plies within its make-up. These plies allow for more stability and performance support when driving. Tire plies are so good for the construction of a tire that sometimes a tire can just be repaired instead of replaced, depending on the damage.
What Are Tire Plies?
Tire plies are what make up a tire and by that, it means more than what is on the outside but the inside too! Tires are compiled of layers and it’s these layers that determine the Ply.
Spanning the infrastructure of a tire, these compounds are made of rubber and various other materials. Reinforcement is completed with an additional layer that has steel or nylon cables as well as other mediums. All of this allows for tires to keep their shape and stability at working pressures.
History of Tire Ply
The modern ply tire, as we know it, was first patented in design only in 1914 in London. It was in 1946 that the first radial-ply tire was invented by Michelin in France. Here it was designed, patented, created, and finally mass produced as the passenger tire of choice.
From here, this tire became the standard and design for all tires succeeding it. Ply tires are known as radial due to the fact that cord plies are set in a pattern of 90 degrees from the center of the tire. From this, it is further reinforced by a belt of fabricated steel that goes into the layers that create the wheel.
What Does 6 Ply or 8 Ply Even Mean?
The difference between 6-ply and 8-ply is rather small. However, it can make a big difference depending on the type of vehicle you drive. Therefore, it is very important to check the owner’s manual or look up the details of your specific vehicle type to determine what works best.
Some tires have a spot on them that has the words Load Range and a letter from A – F. Going up in increments of 2, an A range has 2 plies, B has 4, C has 6, and so on. However, Load Range is an older measure of ply rating, as today ply rating is no longer directly tied with the number of plies used in the tire structure.
Ply ratings are used to refer to the number of physical plies in a tire. Modern-day technology has allowed us to create fewer plies for the same load ratings. Today, an 8-ply tire may only have 3 to 4 physical plies but still carry a larger weight load than a 6-ply tire. Although modern-day 8-ply tires have fewer physical plies they maintain the same load capacity as their predecessors.
How to Tell Your Tire Ply
Tire ply information can be found on your tire’s sidewall. The first thing you might see is something that looks like a bit of a special code. So, let’s break it down for you.
- The first thing is a letter. This determines tire type. P stands for Passenger and generally is 4-ply or lower. LT stands for Light Truck and is normally 6-ply or higher. XL stands for Extra Load and is generally 4-ply rated but with a higher-than-normal load index. ST stands for Special Trailer.
- Following this letter will be a 3-digit number. This is the tire’s width.
- After these 3 numbers, there will be a slash symbol and to the right of that, there will be a 2-digit number. This is the aspect ratio, also known as the profile, stating height.
- From here there will be another singular letter. This will detail the construction type. R stands for Radial, and D is for bias ply tires.
- Another 2-digit number follows this letter and specifies the diameter of the wheel.
- These next two or sometimes 3 numbers are stating the load index of the tire. The load index is calculated by each tire and measured when the tire is inflated to its’ maximum air pressure.
- The final bit of information in this series of numbers and letters on the sidewall of a tire is a singular letter, or in some cases 2 letters. This tells of the speed rating and what top speed is safe for traveling along on this tire.
All of this information sums up just about everything regarding the tire, how it is made, and what can be expected of it as far as performance goes.
The Importance of the Right Ply Tires for Your Car
Radial tires already give us so many advancements in performance, tire life, gas mileage, longer tread life, and more. Whether the tire has an inner tube design or is tubeless, ply helps the rubber maintain its structure when inflated.
These are some of the advantages that modern radial tires and their plies have given automobile drivers in the past 50 years:
- Contact from the tire to the road is more stable with less slipping.
- Reduced costs all around making and selling the tire.
- Longer tread life with wider wheels than previously manufactured.
- Plies with steel belting last longer and are stronger.
- Sidewalls that are flexible.
- Better fuel efficiency due to less rolling resistance while operating the vehicle.
It may look like fun having larger tires than is normally fitted for your car, but these things actually affect how your vehicle handles and performs on the open road. Checking with your local auto authority on what works for your car, truck, or SUV that will be best. The wrong size tire or incorrect ply can cause unwanted issues.
In daily life, it is generally best to use radial ply tires as they are designed for our more modern-day uses on manufactured highways and roads. Bias ply tires are typically used for off-roading or agricultural-type vehicles. Having the correct tire and ply is best for maintaining an efficiently performing vehicle.