How to read motorcycle tire size? How motorcycle tire work?

How to read motorcycle tire size? If you have ever studied a motorcycle, looked at the tires, or maybe never noticed until you went to put air in your bike’s tire, you probably saw some numbers and perhaps even letters on the side. If you are curious as to what this means, it is relatively simple. These numbers list information about your tires regarding the size.

How to read motorcycle tire size?

If you don’t know your motorcycle’s or scooter’s tire size, please check out our guide on how to read a motorcycle tire

First Number

The first number inscribed on a motorcycle tire is there to indicate the width of your tire in millimeters. This width is measured by way of a straight line through the tire. It goes from one edge of a motorcycle tires tread to the other side.

How to read motorcycle tire size

Sometimes this measurement can be denoted in inches, but the metric system is conventional for the first number. If at first glance, you see letters instead of a digit, you have a tire that is written with alphanumeric measurements. The codes are translated for you if you read on.

Second Number

The second number imprinted on your motorcycle tires represents the aspect ratio. The aspect ratio describes the height, or how tall the tire happens to be in relationship to the width of the bike’s tire. This aspect ratio can be found amid the tire width and the tire height and is written as a percentage.

In other words, the larger this second number is, the taller your motorcycle tire will be. For example, a tire that is written 130/90 means that it has a width of 130 mm and it is 90 percent as tall as the given width. When you calculate 90 percent of 130, that means it is 117 mm tall.

Third Number

The third number on your tires indicates, more simply, the rim size or the circumference of your wheel. So, if the number is 18, that means your tire rim is 18 inches. A tire with a 16 as the third number has a rim size of 16, and so on.

Alphanumeric Numbers

Some motorcycle tires have alphanumeric numbers, for example, MJ90 17. This is basically writing the same thing as the digital example only in a coded fashion.

The M stands for a tire that meant to be used on a motorcycle, the following letter is the width code, and the number (such as 90 in this case) still stands for the aspect ratio. In this example, 17 stays the same and represents the rim size.

The alphanumeric system for motorcycle tires states back before the metric system. In those days, motorcycle tires were not designed to be much bigger than an MV85 or a tire with a width of 150 mm. Tires that are made for modern bikes that are also more substantial than 155 mm in width will have the metric designation and will not have an alphanumeric code.

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Alphanumeric codes can be interpreted in metric (mm) or in inches. There are codes for both the front and rear tires, as motorcycle usually have different sizes for the front and the back.

Speed Rating

To further add to (and possibly confuse) the code of reading tires, there are also speed ratings denoted by letters. Speed ratings list the maximum pace the tire is designed to handle, and should not surpass that. These speed rating marks are smart to be aware of if you like to test the limits of your bike because having a blow out at top speed can be lethal. These ratings are listed as follows.

Once you have your first, second, and third number down and understand the speed ratings, you will be able to interpret the numbers on a motorcycle tire much more straightforward. You will also be more equipped to know how much speed your bike can handle—the engine isn’t the only factor in that equation, tires play a role in the maximum pace, too.

How to read motorcycle tire size

Motorcycle tire quality can be part of the listing when you are buying tires. Several options exist for different conditions and diverse bikes. For instance, you could get the same size motorcycle tire in a sport touring, a performance road or cruising, off-road, motocross, desert, or city version, along with numerous other options.


As with anything, the options you select in your tire will determine the value. Generally, the prices will range roughly from $70 to $160. Some shops charge for installation of the tire, some don’t, and many will charge a small balancing fee.

Retreaded tires can cost around 30 to 50 percent less than brand new tires. However, these must be carefully inspected to be sure the constitution of the tire is still sound.

The prices of motorcycles will generally influence the range your tires will cost, as tires for something like a Ducati can cost more than something based on used motorcycle values. Getting specialized tires with premium treads will naturally up the price tag.

Load Rating and Date

Not all, but some motorcycle tires may have a load rating for the given size. This can be more often the case with rear tires or four more substantial touring bikes. You may have also noticed a date stamped on your tire sidewall.

You will generally see a four-digit number after the word “DOT, “ and this indicates the week and year your tire was made. For instance, the 37th week of 2018 would be written as 3718.

Other Terms

If you need to brush up on further tire construction terminology, there are only a few terms that are absolutely essential to know. More research can always be done to learn further details within these terms, but the basics are as follows.


The tread is the portion of your tire that touches the road. Generally speaking, smoother tire tread will grip better on even, slick, and dry services. While thicker or chunkier treads are better for off-road conditions.

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There are various patterns designed for streets that perform best in wet and slippery weather. Many off-road tires also are available in a vast array of different surfaces, ranging from packed down soil to loose sand.


The bead of a tire is the portion that connects to the wheel. Generally, this is a steel wire that is coated heavily in rubber. The bead of your tire is meant to have a snug fit against the wheel to avoid your wheels from slipping within the tire.


Your tire carcass is essentially the body that is underneath the tread. In the case of motorcycle tires, they can be bias-ply or radial. This refers to the way the carcass of your tire is designed. In radial tires, reinforcing belts run from a bead on one side to the bead on the opposite side across your tread.

Additionally, tires with bias-ply contain belts running from each bead to the other at 30° to 40° angle. These cords are often made of fiber chords of fiberglass, polyester, or aramid and help to add strength to the integrity of what you are riding on.


The sidewall of your motorcycle tire explains itself and its name. It is the wall that runs between the bead at the wheel and the tread of your tire, basically the side surface. Your sidewalls offer your tires a lot of their handling capability and load transfer performance.

How does motorcycle tire sizing work?

There are several things to consider when selecting the correct motorcycle tires. Size, dimensions, and other factors will affect the performance and safety of your bike. While there are a lot of aspects to making the best choice, it doesn’t have to be difficult. Here, we’ll guide you through each step in determining motorcycle tire sizes, explained so that you can go ahead and hit the open road!

How to read motorcycle tire size

There are five main aspects to determining the ideal motorcycle tire sizing: width, aspect ratio, speed rating, tire construction and rim diameter. Let’s take a look at each:


The first number or second letter in a tire size represents the nominal width. Width is measured in a straight line from the furthest point on one sidewall, across the tread, to the furthest point on the opposite sidewall.

If there is any question whether or not a larger than OEM tire will fit your bike, youre encouraged to call Tech Service. The different size numbering systems specify widths in different measurements. You can view a width cross reference table below .

Aspect ratio

You use the aspect ratio to indicate a tire’s cross-sectional profile. A smaller number means a lower profile, and the height-to-width ratio is shown as a percent.

For example, if the aspect ratio is 90, that means that your tire’s cross-sectional height is 90% of its width. If the tire has the metric, alpha or low-profile inch numbering system, the aspect ratio will appear immediately after the width.

Speed rating

A speed rating provides the maximum speed at which a tire can be used based on maximum load and inflation pressure. To find the maximum load and inflation pressure, you’ll need to check the sidewall of the tire. A speed rating also has a letter code, and that is immediately after the width and aspect ratio.

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It’s part of the three-digit load/speed index. This is on the tire, immediately after the complete size designation. A Z-rated tire has no maximum speed — this rating is for more than 149mph.

Tire construction

After the speed rating is the tire construction, which has two options: Belted (B) or Radial (R). “Belted” means fiberglass, Kevlar or aramid fiber belts, which has added strength and load capacity.

But, if a tire does not have (R), then it is bias-ply, which means that it has multiple, overlapping rubber plies. These overlapping plies form a thick layer that is sensitive to overheating and is less flexible.

Rim diameter

Rim diameter is the diameter of the rim/wheel on which the tire will be mounted, in inches.

What are the different types of motorcycle tires?

How to read motorcycle tire size

There are several different types of motorcycle tires available, each designed for specific riding conditions and styles. These include:

  • Street Tires: These tires are designed for daily use on paved roads and are typically made with a harder rubber compound to provide longer tread life. They have a smooth tread pattern that is optimized for traction on dry pavement.
  • Sport Tires: These tires are designed for high-performance riding and are typically made with a softer rubber compound to provide better grip and handling at high speeds. They have a more aggressive tread pattern that is optimized for traction on both wet and dry pavement.
  • Touring Tires: These tires are designed for long-distance riding and are typically made with a harder rubber compound to provide longer tread life. They have a more rounded tread pattern that is optimized for stability and comfort during extended rides.
  • Off-Road Tires: These tires are designed for use on dirt, gravel, and other unpaved surfaces. They have a deep, aggressive tread pattern that is optimized for traction in loose or muddy conditions.
  • Dual-Sport Tires: These tires are designed for use on both paved and unpaved surfaces. They have a more intermediate tread pattern that is optimized for good traction on both types of road surfaces.
  • Scooter Tires: These tires are designed for use on scooters and other small-displacement motorcycles. They have a smooth tread pattern that is optimized for stability and fuel economy.

It’s important to note that different manufacturers may have slight variations in their tire types and it’s also best to check the manufacturer’s recommendations for your specific motorcycle model.


What does 120 70 r17 mean?

In this case they are alphabetical designations. Going back to the example size 120/70ZR17, in this case 3 types of measurements are combined: 120 in millimeters, 70 in percentage and 17 in inches.

What does 120 70 ZR17 m c 58W mean?

Very quick tires will often list two speed ratings: 120/70 ZR17 M/C (58W). ” Z” is a non-specific rating, indicating that a tire is limited somewhere beyond 240 km/h. “W” is the actual limit: a meaty 270 km/h. In this way, W- and Y-rated tires are always Z-rated as well.

What is the difference between ZR and R in tire size?

The ZR rating indicates that a tire is capable of high-speed operation, while an R rating indicates that a tire is rated for speeds up to 106 mph. ZR tires are typically used on high-performance vehicles, while R-rated tires are more common on passenger cars.

Above is information about How to read motorcycle tire size? that we have compiled. Hopefully, through the above content, you have a more detailed understanding of How does motorcycle tire sizing work? Thank you for reading our post.

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