If you are a responsible truck owner, you take good care of your vehicle, maintain it properly and have read some of our previous blog posts, there is a good chance you know quite a lot about your truck tires. And that’s great! It’s not enough to spend a lot of money on a new set of tires, knowledge really is the key. The more you know about your vehicle and its specific parts, the better you can use that knowledge in a way that will help your truck to serve you longer. If you have already had a browse on our website and blog, you know how to spot and prevent irregular tire wear, choose the right truck tire sizing and maintain them. But do you know how your tires are built? Have you heard about the DOT code? No? Well, it’s about time you do your homework. Here’s some useful information to start with.
How are your tires made?
Okay, let’s start with some basics. Have you ever wondered how tires are actually made?
It is not as simple as it may seem. Actually, there are over 200 different materials needed to make a tire. And trust us, the reason is not simply to be fancy or extravagant. Each part of the tire has a different task, is used differently and the ways in which they wear differs too. That’s why it is so important that each part is made of the right material, appropriate for the task it needs to perform to assure safety and longevity. The way a tire is made can even impact the whole vehicle’s fuel efficiency, performance and eco-friendliness.
The main material used to manufacture a tire is obviously rubber (natural rubber and synthetic), but other components include fiber materials, silica, carbon black, sulfur, steel and many others. If it wasn’t for all these ingredients, your tires would not be so elastic or resistant.
There are seven main layers that your tire is made of:
- Inner liner － this part of the tire is made of a thick layer of air-impermeable rubber. The main task of the inner liner is to hold high-pressure air inside.
- Bead － the bead is the part which is in contact with the rim. Some believe that it is the most important part of the tire, without this the tire is not securely attached to the rim. There are various materials used to make it, but they usually include rubber and flipper and it is reinforced with a sturdy material such as steel cable.
- Carcass － this is the internal cord layer of the tire. Its main task is to sustain load and absorb internal air pressure, and weight shock. In simple words, the carcass is the framework of the tire and it is one of the most important parts.
- Breaker － also known as “belt”, this is the layer between the tread and the carcass and, simply put, it’s a reinforcement layer. Its role is to reinforce the strength of the tread and tighten the carcass. The breaker is also meant to absorb external shock and prevent the separation of the rubber layer and splintering.
- Sidewall － as the name suggests, the sidewall is the side part of the tire. It is located between the bead and the shoulder and its main task is to protect the carcass on the inside. The sidewall also determines a comfortable riding experience when it is flexible enough. This is also the most “informative” part of your tire. You can find the tire sizing, type of tire, tread pattern, structure as well as some information about the manufacturer and brand name there.
- Tread － this part of your tire is simply that thick layer of rubber which makes contact with the ground and the road surface. It needs to be very resistant in order to protect the carcass and the belt beneath it.The materials used for this part often determine the tire’s driving lifespan － the stronger the anti-inner abrasion rubber, the more resistant it is.
- Shoulder － the shoulder of the tire is located between the centre of the tread and the sidewall. It is one of the the most complex and thickest parts on a tire. Thanks to the shoulder the tire can perform better during cornering maneuvers.
Do you know your tire sizing?
If you don’t know much about tire sizing, there is nothing wrong with that. Most of us just buy the type and size of tire suggested by the vehicle manufacturer. And that is one of the main rules when it comes to buying new tires － if there is no reason to buy any other type or size – stick with what you know. It’s a matter of safety and good performance. The people who designed your truck know best what kind of tires it needs.
However, this does not mean that you don’t need to know how to read tire sizing properly. You never know what sort of situation you might find yourself in and it can come in handy one day to know how it’s done.
Looking from left to right, the first number located on the sidewall of the tire indicates the tire width or its thickness. It can also be called “section width” so don’t be surprised when you hear that term. The width of the tire is measured from the outer sidewall to the inner sidewall. If you’re wondering why the width number written on your tires seems so high, it is because they are measured in millimeters.
The next number (after the slash mark) is the aspect ratio. This represents the relationship of the tire’s sidewall height to the tire’s width and is measured in percentages. For example, a 70% aspect ratio shows that the tire’s height is equal to 70% of the tire’s width.
Right after the aspect ratio you can find the construction symbol. The most popular letter is R which refers to the “radial internal construction”. You can also find D (diagonal construction) or B (belted construction).
The last number is the wheel diameter. This is measured in inches and shows what size of wheel the tire is designed to fit.
What is the DOT code and how do you read it?
The tire sizing numbers and symbols are not the only things written on your tires. While some people know how to read the sizing (and now you do as well) the DOT codes are much more mysterious for most.
What does DOT stand for? It refers to: Department of Transportation Safety Code. It consists of twelve different numbers and letters, and contains all the important information about your tires － such as where they were made and when.
The first number (after “DOT”) is the plant code and it refers to the plant where your tires were made. The next one is the optional code for size. After this, you will find the dimensional code and the last number indicates the week and year of production.
So if you can decode your tire’s DOT and tire sizing codes, you will know pretty much everything about them.
Remember that the more you know about your truck, the better care you can take of it. Knowing how to maintain your vehicle, what parts to get when they need replacing and how to use them properly is crucial to safe and economic driving. So try to learn a lot about your truck and let us know if you have any questions about the tires. We really know everything there is to know about tires and we love sharing this knowledge with others. So don’t hesitate and give us a call if you have a question!