Tire Size Meaning

Whatever vehicle you use, whether it has two wheels or four, and whatever horsepower you have on your ride, most people fail to realize that the only things responsible for putting all that power down to the road, are your tires.

Tires are a critical part of your vehicle as it directly affects the handling, grip, traction and maneuverability. It’s not just the dynamics of the vehicle that are dependent on your tires, but also the fuel economy and life of the tires themselves. Tire pressure is something to be taken seriously, and regular checks are necessary for those vehicles that are not equipped with a tire pressure monitor. So enough about tires, and lets talk about the tire. If you’ve looked at your tires, you’ve probably noticed many numbers and if you’ve wonder what they all mean, this is where you get all your questions answered.

The tire size meaning is dependent on four factors – width or tire section, height or tire profile, type of design and diameter. Let’s consider a common car tire size which is used on most sedans 225/50 R17. Here, 225 signifies the width of the tire in millimeters. It’s interesting to note that a motorcycle tire size always ends with a 0, while that of four wheel vehicles ends with a 5. That means, you can have a 190-section for a motorcycle, but a car will use a 185 or a 195-section.

Now onto profile. In the above example, 225/50 R17, 50 is the aspect ratio, or the profile of the tire as a percentage of it’s width. The higher the profile, the taller the side wall of the tire will be. The side wall is the rubber between the outer belt that is in contact with the road and the outer edge of the wheel rim. So, a 225/45 R17 tire will have a lesser diameter across than a 225/55 R17 tire.

“R” signifies that the tire is a radial. Which means that it has steel belt across the section, or circumferential width. This provides added strength or durability and improves the life of the tire. If the tire is not a radial, it will have a number of plies. This is mentioned in the ply rating on the tire. In that case, the tire size would read, for example, 225/50-17 8PR.

Finally, “17″ signifies the wheel rim diameter on which the tire is mounted. This has to be the inner diameter of the tire. You cannot use an R18 tire on a 17″ wheel rim or vice versa. Another important aspect, is the width of the rim, which is usually mentioned in inches as 8.5×17. 8.5 inches is 215.9 millimeters. Which means you can have 225, 235 or even 245 section tire sizes mounted onto this rim. However, you have to ensure that the tire isn’t too wide for the rim, and be doubly sure it doesn’t rub along the wheel arch or the underbody.

In case you’ve seen tires on some older vehicles, specifically motorcycles, you may notice something like 3.50-19 6PR, which until recently was the tire size used by classic motorcycle manufacturers. Here, 3.50 is the width of the tire in inches, 19 is the rim diameter and the tire has a ply rating of 6.

If you are interested and want to know more about tires, about its sizes and in general want to understand tire size meaning, than read this article. It is no secret that the parameters of tires and wheels have to match each other, because only in this way, you can be sure that the tires and wheels are chosen correctly. Such geometric parameters of the tires as the width of the rim radius, diameter, and some other features have to be in accordance with the parameters of the wheels.

It is known to everyone that the width of the tire in any case should not exceed the width of the rim wheel drive for more than one and a half times, but few are aware that an order of magnitude more serious problems might occur if the reverse situation occurs (i.e. the width of the tire is less than the wheel disk rim). More specifically, it leads to a sharp deterioration in the characteristics of tires, with potentially quite serious, sometimes fatal, consequences. First of all, the problem will affect the properties of the tire and will break its resistance to aquaplaning.

Without exception, all tire manufacturers produce their products, taking into account the fact that the tires will be used with wheels of a certain size. And so, whether these wheels are for ford, Mercedes, BMW, or any other car, the tires have to be chosen in full accordance to them.

However, compliance of the size for the mounting rim is not the only thing you should look for when choosing tires, because you should take into account in addition the tire size meaning. Sufficiently, great importance has the size of tires, which, in essence, is the main criterion for their choice from the standpoint of the consumer. At same time, you should consider the value of a radial tire design and tire width. The tire must not be wider than the drive on which will be assembling more than 30%. Therefore, it is better to buy this and another at the same time in one shop, which specializes in tires for wheels.

When choosing tires, one should pay attention to its figures such as the ratio of height to width profile. Middle range is considered to be 60-80. If your tires deviate from these figures, in one way or another, they are called a low-profile or high profile tires.

As a rule, all the outlined characteristics of tires, mentioned in the article, are specified in the documentation and presented on the label of the product.

In addition to the important characteristics of car tires, we have to separate the so-called load index and speed index / tire speed ratings. Information about them is usually placed on the sidewall of the tires a numerical index, which consists of two characters.

If the tread of the rubber has a directional pattern, the sidewall of the tire, you can detect the direction of the arrow, which tells how the tires should be installed. Remember that if the rubber will be installed incorrectly, it can be really dangerous.

I hope, now you are aware about the tire size meaning and it will eventually help you to choose tires correctly!