What Are the Different Parts of a Tire (and Why Does it Matter)?
To know what you’re getting, you first have to understand what you’re looking at. Unfortunately, tire shopping can often feel like revisiting your high school calculus textbook, but this time it’s in a foreign language. It’s difficult to care about “bead filler” and “radial cord body” if you’ve never even heard of the names of different parts of a tire. That’s why we’re here with a little tire education to help you understand the parts of a tire you actually need to know.
Why Should You Care About the Different Parts of a Tire?
Knowing the layers of a car tire can help you understand the difference between getting a good deal on quality tires vs. getting a cheap set of tires that’ll wear out in a year. As the only part of your vehicle that should be making contact with the road, tires are one of the most crucial components of your vehicle. It’s important to know what you’re getting into before making a purchase.
By better understanding the different parts of a tire, you can make an informed decision that’s right for your wallet, your vehicle, and your safety. Though tires can differ depending upon their purpose (i.e., all weather tires, tires for SUVs, etc.) the basic components of tire construction are always the same.
Car Tire Anatomy 101: External Parts
When taking a look at the different parts of a tire, it’s helpful to frame them into two different categories: external and internal.
Sidewall
The part of a tire from the bead to the tread—the side of the tire—is called the sidewall. It forms a protective covering for the cord body. Information about the tire is printed on the sidewall. This information includes the tire size, load index, and speed rating. Sidewall rubber compounds are designed to resist damage from ozone, cuts, and snags.
Tread
The tread is the portion of the tire that comes in contact with the road surface. The tread’s compound and its design have to balance wear, traction, handling, fuel economy, resistance, and other characteristics of the tire. The design of a tire’s tread can vary greatly, depending on the primary purpose of the tire (i.e., noise reduction, handling, tread longevity).
Car Tire Anatomy 101: Internal Parts
Though less noticeable than tire tread, the internal parts of a tire are just as crucial as the external, and it’s important to know the tire components that lie under the surface when searching for quality tires for your vehicle.
Tire Beads
Tire beads are actually a rubber-coated loop of high-strength steel cable. The role of tire beads is to hold the tire on the rim and prevent it from sliding out of place when the wheel rolls. Typically, tire beads are made of copper, brass, or bronze-plated high tensile steel writes wound into a rubber band.
Bead Filler
Found within tire beads is a rubber compound known as bead filler. The purpose of bead filler is to stabilize the lower sidewall and bead area. The density and stiffness of a tire’s bead filler help determine a tire’s performance characteristics.
Radial Cord Body
The cord body consists of rubber-coated fabric cords, called body plies, which make up the cord body. Body plies can be made of rayon, nylon, and – less commonly – polyester. The purpose of the cord body is to lend strength to the tire and transmit forces from the tread to the wheel itself, propelling the vehicle forward.
Inner Liner
The inner liner is a rubber compound secured to the inside of the cord body that retains air under pressure. The main purpose of the inner liner is to work in tandem with a tire’s beads and bead filler to hold air within the tire walls.
Belt Plies
Belt plies are two or more layers of cord situated under the tread area of a tire. The primary role of belt plies is to reinforce the strength and stability of the tire tread. Belt plies help improve tire performance, affecting characteristics like tire mileage, impact resistance, and traction. The most commonly used cord material in belt plies is steel.
Tire Tread: A Crucial Component
Tire tread is one of the most basic parts of a tire, and it’s also one of the most important parts. The National Highway Traffic Safety Administration (NHTSA) estimates around 11,000 accidents occur annually because of worn tire tread.
What Affects Tire Tread?
A factor that affects tire tread – which often goes unnoticed – is cold temperatures. Studies show tires lose about one to two pounds of pressure for every 1- degree the temperature drops. Inadequate tire pressure can shorten your tire’s lifespan, and affect performance capabilities like MPG (miles per gallon) and safety, as low tire pressure causes your tire to be more susceptible to blowouts and less able to grip the road. At K&W Tire, our teams perform free alignment checks to keep your tires from premature wear, as misaligned tires can also reduce longevity.
The Penny Test
When it comes to checking the status of your tire’s tread, you may have just what you need within your own wallet. Most people are familiar with the penny test: placing a penny headfirst into various tread grooves. If the top of President Lincoln’s head is visible (like the image above), then your tired tread is too worn and you need to replace that tire.
A simple penny has become the at-home staple for determining whether you need new tires or not. There are many reasons to conduct the penny test, including:
- Determining the tread depth of a tire.
- To get a better understanding of your vehicle’s safety. For instance, if a tire is bald, then it won’t grip the road very well.
- To prepare for winter or harsher weather conditions. In wet weather conditions, a vehicle (especially one with tires that have low tread) is prone to hydroplaning with bald tires.
Conducting the test:
- Take a penny and place it upside down in the tread groove.
- If you see all of Lincoln’s head then it is time for new tires.
- If the penny is at least as deep as Lincoln’s forehead, then you have good tire tread.
Selecting a Tire Based on Your Priorities
We understand no one really enjoys buying tires. It’s one of those grudge purchases you have to make to keep your vehicle running smoothly. But the most common mistakes tire buyers often make is choosing a tire solely based on price. But in addition to ensuring the tire you purchase is made up of quality components, the next thing to keep in mind is what you use your vehicle for.
How to Choose the Right Tires
One of the best ways to narrow down the right tire for your vehicle is to think of the following specifications and make a list of the three that are most important to you:
- Vehicle Handling
- Noise
- Temperature
- Traction
- Tread Wear (longevity)
While each item on the above list is important, you probably wouldn’t be looking for the same characteristics in tires for your sports car as you would for your minivan. Tire features like traction, tread wear, and temperature are going to be of utmost importance for a vehicle regularly used to haul your family around. Performance features like handling are probably more highly sought after for car drivers looking for a new set of tires to put on their convertible for a weekend cruise.
Choosing the right tires for your vehicle make and model can be confusing and difficult. That’s why our in-store experts are always ready to help you find the right set of tires to keep you safe on the road.