A Technician’s Guide to Tires: Materials, Sizing and More

Tires: They make the vehicle — and the automotive technician world — go round. Although seemingly simple circles of rubber, tires play a vital role in a car’s speed, fuel efficiency and overall performance.

To help you understand better, we worked with Continental Tire — the official tire of Universal Technical Institute (UTI) — to put together a technician’s guide on tires. Read below!

What Are Tires Made Of?

You might be thinking, “Aren’t tires just made of rubber?” And to a point, you’d be correct, but there are many intricate parts that make up a tire. In fact, there are about 25 components, with 12 of them being different rubber compounds.

Starting from the inside and ending with the tread of the tire, here are its main components:

Bead

The bead core is a steel wire embedded in rubber, and it secures the tire firmly to the wheel. These layers of bead fillers and reinforcements enhance directional stability and steering comfort.

Sidewall

Made of natural rubbers extracted from trees grown in plantations, the sidewall is added to protect the casing from climatic conditions and other external damage.

Inner Liner

Next are the inner liners, which are usually made of a synthetic rubber called butyl. Liners seal the inner chamber and control air pressure, basically acting as the “tube” of the tire.

Belts and Plies

Now that you have the reinforcement, sidewalls and steering aids, you’re going to need help with the shaping of the tire and maintaining speed. That’s where the belts and plies come in. Rubberized textile cord ply and Steel Cord™ for belt plies maintain the shape while reducing rolling resistance. The jointless cap plies create a twine-like layer just before the tread that enables high speeds.

Tread

The tread is the top part of the tire connecting to the sidewall. It consists of natural and synthetic rubber and has three parts: cap, base and shoulder. The cap provides grip on road surfaces and directional stability, the base reduces rolling resistance and protects the internal structure from damage, and the shoulder gives a smooth transition from tread to sidewall.

Understanding Tire Sizing

When in need of a tire change, it’s important to know what size fits your vehicle. Locating the tire size is simple; it’s on the tire itself right on the sidewall. You’ll find a lot of words on the side of the tire, but the size usually looks something like: P245/70R17

Let’s break it down.

• The P stands for P-metric, which simply means it meets standards. The P may or may not be present on your tire sizing.
• 245 is the tire width, which in this case is 245 millimeters wide.
• After the slash, you see the number 70. This is essentially the height, but more technically, it’s the aspect ratio of the width. So, in the example above, the tire’s height is 70% of its width.
• The R stands for radial, meaning the layers are radially configured on the tire.
• The last number, 17, is the wheel diameter.

What Is Tire Alignment?

Alignment is important for suspension tuning and operating your vehicle’s tires.

Your vehicle’s alignment is a complex system of suspension angles and various suspension components that are always being adjusted. When your tires are properly aligned, you can expect better tire performance and fuel efficiency, as well as a more comfortable ride.

Here’s why: As you drive your vehicle, it’s common to hit potholes or curbs, and that can cause misalignment. When misaligned, the tires hit the road unevenly, making the car work harder to travel at high speeds. When the car has to work harder, it becomes less fuel efficient, and you may experience a bumpier ride.

It's best to refer to your owner’s manual, but you should have your tires aligned once to twice a year to help keep your suspension and tires running smoothly.

The Importance of Tire Rotation

Whether you have a front-wheel, rear-wheel, four-wheel or all-wheel drive vehicle, tire rotation is important to equalize wear.

Generally, the two front tires wear down more quickly than the rear tires. Whenever you turn, parallel park or U-turn, more pressure is placed on the outer edge of the front tires.

By regularly rotating your vehicle’s tires, you ensure a more even wear. Doing so doesn’t just extend the time between buying new tires, it keeps your car safe, as unevenly worn tires decrease steering control.

You should rotate your tires every 6,000 to 8,000 miles on average. To determine rotation pattern and interval, it’s best to follow the vehicle manufacturer’s recommendation, which you can find in the owner’s manual.

Thinking of Pursuing a Career in the Automotive Industry?

If you have an interest in tires and all things automotive, a career as an technician could be the perfect fit for you.1 At UTI, you could be prepared to enter an exciting industry as an automotive technician in less than a year.7

You’ll also get access to UTI’s many industry relationships — including Continental Tire, which provides tires and tire racks at our campuses.

UTI has campus locations nationwide. To learn more and to connect with one of our Admissions Representatives, click on the button below.