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Tag: Do motorcycle tires have aspect ratio

how do motorcycle tire sizes work

How do you read motorcycle tire sizes?THE FIRST NUMBER – WIDTH. The 130 indicates the width of the tire in millimeters.THE SECOND NUMBER – ASPECT RATIO. The second number,the 90,represents how tall a motorcycle tire is in relationship to its width.THE THIRD NUMBER – RIM SIZE. The last number,17,refers to the tire’s rim diameter expressed in inches.

How to read motorcycle tire sizes?

Inner tubes are common, though tires are also run without tubes on many modern motorcycles with mag wheels. How to Read Motorcycle Tire Sizes? B – Aspect Ratio. The smaller the number the lower profile of the tire. In metric this is a ratio between height and width. ex. A 170/80 means the width is 170mm, and the height would be 80% of that. )

What does rim diameter mean on a motorcycle?

Rim diameter is the diameter of the rim/wheel on which the tire will be mounted, in inches. Let’s check out some examples of how to read motorcycle tire dimensions:

Do motorcycle tires have aspect ratio?

Often, older motorcycle tires have a Standard Inch System. These tires do not have an aspect ratio designation marking. The cross-section tire height is 100% of the width. An inch-sized tire is bias-ply construction and is not belted. However, these are being phased out and are not used on newer motorcycles.

Are motorcycle tire sizes interchangeable?

Because motorcycle tires are manufactured worldwide, there are variations in size designations. Therefore, the chart below does not display exact interchangeability, but it can give you an idea of how to compare widths and replacement sizes. This table should not be used for tires with aspect ratios lower than 80%.

What are the factors that determine the size of a motorcycle tire?

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:

How to measure width of bike tire?

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.

How to find tire speed rating?

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. 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. Check out this table to see what letters correspond with what speed ratings:

What is an inch tire?

These tires do not have an aspect ratio designation marking. The cross-section tire height is 100% of the width. An inch-sized tire is bias-ply construction and is not belted. However, these are being phased out and are not used on newer motorcycles.

What is metric tire?

Metric. Metric tires are most commonly used and can work for sport bikes, cruisers, touring bikes and others. If there is no speed rating, the “M” will precede the metric size. After the speed rating, there will be a “B” or “R” to indicate if it is belted or radial tire construction.

What is the alpha size on a motorcycle?

The Alpha size designation is most often used for touring motorcycle tires. Even if a tire doesn’t have a“B” designation after the speed rating, it could be belted.

What to consider when selecting motorcycle tires?

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.

Tire size

Each motorcycle model requires specific tire sizes that are indicated by the manufacturer in its technical data sheet. It is very important to try to stick to the recommendations for safety and to adhere to the regulations of the road.


You may have noticed that we are still missing a piece of information from the previous sizes (120/70 ZR 17). These letters indicate the type of internal construction of the tire, whether it is radial or diagonal. If it is radial, it is indicated with a letter R or ZR, while if it is diagonal, it is usually not indicated, i.e.

Load capacity and speed symbol

In this section we are going to look at the load capacity index and the speed category symbol, i.e. numbers and a letter after the tire size.

Other data

If we take a closer look at our tires we will see that there is even more information about them on their sidewall, although with somewhat smaller letters.

What does 3.25H-19 mean?

Another thing to note is that these tires are not belted and are of bias-ply construction. An example is 3.25H-19. 3.25 symbolizes the width, H symbolizes the speed rating, and. 19 symbolizes the rim diameter in inches. The aspect ratio, though not indicated, is 100% meaning the height of the tire is 100% the width of the tire.

What is the metric system on a motorcycle?

Metric System. This system measures the size in millimeters. It is the most commonly used system for motorcycle tires, which is a set of three numbers and letters implying the width of the tire, the aspect ratio of the tire (ratio of tire ‘s height to the width) and lastly the rim size given in inches. Immediately after the speed rating, you will …

What is 50 aspect ratio?

50 = aspect ratio which is the percentage of the height of the tire to the tire’s width,

What does M mean on a motorcycle tire?

M is used to denote that the tire is a motorcycle tire

What does 90 mean in physics?

90 denote the aspect ratio. In this case it is 90%

What is the letter that precedes the speed rating?

A· The speed rating is usually preceded by letter “S”

How to tell if a tire is a smooth tread?

You can feel this condition by running a hand both directions along the tire circumference— it will have a smooth, yet ramped transition as it rolls up and over to the next tread in one direction. Feeling the other direction will be more resistant as the hand hits the face of the sharp higher edges.

How to tell if a motorcycle tire needs replacement?

Oftentimes, a quick visual inspection can determine if a motorcycle tire is in need of replacement, as a worn tread is easy to spot. Unfortunately, some riders ignore their tires until the belts are visible!

What are tread wear indicators?

Tools exist to measure tread depth, and if you don’t have one, most tires are manufactured with tread wear indicators to aid in evaluating how much life remains in the tire. A visual inspection can reveal cracks and dry rot, but how do you determine tire age?

What does the last 4 digits on a tire mean?

Department of Transportation (DOT) information is included on the sidewall, and the last 4 digits of the DOT information indicate when the tire was manufactured. For example, if the last 4 digits are “2517,” we know that tire was made during the 25 th week of 2017.

What happens when you brake a tire?

As braking pressure is applied, the tire deforms and rolls backwards. This wears heavily on the leading edge of the tire tread, like an eraser. The result is a low spot on the leading edge of the tread and a high spot on the training edge. The wear resembles a subtle shape of a saw blade.

What is a cupping tire?

Uneven Wear Patterns. Tire cupping is a specific type of uneven tire wear and common on all motorcycles. It’s a condition that occurs from normal braking, particularly on the front tire on street bikes and rear tire on cruisers, which are often used as the primary braking wheel.

How long do motorcycle tires last?

As a general rule of thumb, the lifespan of your motorcycle tires will typically not last beyond five years. However, it’s more important to look out for the following signs when it comes to evaluating when to replace them.

Motorcycle Tire Sizes Rim Width Chart

British motorcycle rims (Triumph, BSA, Norton etc.) are marked with a letter and number designation. This is helpful to know what tires you can mount on your rim based on the manufacturer’s specs.

Common Motorcycle Tire Sizes Chart

The following chart shows some common tire sizes, including their width and the diameter. Very handy when choosing which tire will fit your bike, or which motorcycle rear fender to buy to fit the tire you want to run on your new build!

Todd Muller

Todd Muller is known for his experience and knowledge of motorcycle mechanics. His specialties include Triumph and Harley-Davidsons, and he has helped thousands of people around the world with everything from how to wire their custom bike to rebuilding an engine.

Can I mix radial and bias-ply tires? Can I switch from bias to radials?

Again, we respect a customer’s right to choose, but we only recommend stick ing with a manufacturer’s recommended tire construction type.

Can I use tires with a different load/speed rating?

Normally, a downgrade in load/speed rating is a poor idea and we don ’t recommend it at RevZilla. Maximum load and speed ratings are considered by the manufacturer and they specify tires they believe the bike needs.

What do the B, C, E, etc. after the tire size mean?

If you see a letter and number combo listed after a tire size, that is a tire “service description .” Service descriptions all have a load and speed index, which are easily converted from a number of commonly available tables.

Are chatter/wobble/wear/tread issues caused by a defective tire?

It’s hard to say without having the situation assessed by a trained professional. As a former tire installer, I would say that perhaps two percent of all tire problems were caused by truly defective tires. Chatter from a tire typically comes from normal wear and cupping, and sometimes from incorrect inflation, or a combination of those things. Wobble is almost always caused by misaligned tires, bent axles, or, most commonly, worn bearings. Tread and wear issues are usually caused from wheels having crooked installation or improper inflation.

What is street tread pattern?

Some street tread patterns are designed to do better in the wet and off-road tires come in a wide variety for different surfaces, from hard-packed dirt to sand. Bead: This is the part of the tire that mates to the wheel. It is typically steel wire covered heavily in rubber.

Why is a tire sidewall important?

A small part of the tire, it is vitally important. It gives the tire much of its handling and load transfer characteristics. This is the part of the tire we’re talking about when we reference height, profile, or aspect ratio. Typically, a shorter sidewall yields a stiffer sidewall, which tends to flex less.

How to tell if a tire is old?

Fortunately, it’s easy to tell your tire’s age. Molded into the sidewall of every tire is a DOT code , typically 12-16 digits or so. The code starts with the letters “DOT” and ends with a mishmash of numbers which tell many things, including the date of manufacture and plant it was produced in.

What size rims does a 190/50-17 fit?

But in reality, a 190/50-17 fits properly only on a 6.0-inch rim , and cramming it onto anything smaller severely changes its profile.

What is the difference between a 190 and a 180?

Compared to the correctly sized tire on the same rim, the 190’s profile closely matches the 180’s near the edges of the tread, but is much lower in the center area-equivalent to about a 6mm change in ride height. Effectively, the wider tire will give more rake and trail when the bike is vertical, while keeping close to the original geometry …

When was the tire test published?

This story was originally published as part of the tire test in the June 2002 issue of Sport Rider.

Does the F4i have a wider tire?

With no changes to suspension or ge ometry, the F4i felt substantially different with the wider tire. With the bike straight up and down, steering was slightly sluggish in comparison, but just off vertical, the F4i was quite tippy and darted into corners.

Does a wider tire give more rake?

Effectively , the wider tire will give more rake and trail when the bike is vertical, while keeping close to the original geometry when the bike is leaned over. Accounting for one (by changing ride height) will unduly affect the other.

What is the width of a motorcycle tire?

The tire Width Code is just a letter to substitute for the width of the rim. The width codes below are for motorcycle tires with an aspect ratio of 80 or greater. A code of U means this tire will fit on a rim that is between 2.75 and 3.50 inches wide.

What does it mean when a motorcycle tire is tubeless?

It indicates that the tire is meant for a tubeless application. The majority of modern motorcycles use tubeless tires. If your bike has wire spoke wheels you need to use a tire designed for use with a tube inside. All those spokes and nipples are not air tight.

What does TL mean on a tire catalog?

Sometimes a catalog will list a tire as TL, BL or RWL. These have nothing to do with the size or handling. They are strictly descriptive. They describe the look or another feature of the tire.

What is load index on a tire?

In addition to the information listed above, tires can contain Load Index or Rating info on the sidewall. This refers to how much weight a tire can safely transport. It includes the weight of the bike and rider (s). Not all tire manufacturers make tires in all load indices.

What is the motorcycle tire size code?

Most tire manufacturers use the metric tire size designations now. The size we will use in our example is MU90-16 B. The Motorcycle Code means exactly what it says. Tires made specifically for motorcycles are coded with an M. The tire Width Code is just a letter to substitute for the width of the rim.

What happens if you choose wrong tires?

Wrong selection can result in tire failure, loss of control with serious injury or death. You can also contact the manufacturer of the tires you want to put on your bike. They have reps dedicated to this stuff.

What is a ply rating?

The Ply Rating is a descriptive abbreviation. It refers to the number of plys (layers) that make up the tire. For more on descriptive abbreviations, see sections below. For specific strength of the different ply tires, refer the tire manufacturers literature.

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