# What Do the Numbers on A Dirt Bike Tire Mean?

Dirt bike tires are commonly measured by in millimeters by Width / Aspect Ratio x Rim Diameter (inches). For example, on the tire size above, the aspect ratio is 90% of the tread width (the first number in the tire size), creating a 99-millimeter sidewall height.

Keeping this in consideration, what do the numbers mean on a motorcycle tire?

THE FIRST NUMBER – WIDTH. The 130 indicates the width of the tire in millimeters. This is measured as a straight line through the tyre from one edge of the tire’s tread to the other edge. THE SECOND NUMBER – ASPECT RATIO.

## FAQs on Dirt Bike Tire

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### How Wide Is a Dirt Bike Front Tire?

You can get front dirt bike wheels between 18- and 21-inches. The rear wheel ranges between 17- and 19-inches.

Offroad tire sizes are routinely expressed in the common format, e.g. 235/75R15. In this example, 235 = section width (in millimeters), 75 = aspect ratio (tire height/sidewall profile expressed as a % of tire width), 15 = wheel diameter (in inches).

### What do the letters on a tire mean?

When a letter (R, D, or B) follows the two-digit aspect ratio, it tells us the tire’s construction. In this example, the R means that the tire has radial construction. If there’s a D instead of an R, the tire has a bias ply construction, meaning that the internal body plies of the tire crisscross on a diagonal pattern.

### What does the numbers and letters mean on tires?

The two-digit number after the slash mark in a tire size is the aspect ratio. For example, in a size P215/65 R15 tire, the 65 means that the height is equal to 65% of the tire’s width. The bigger the aspect ratio, the bigger the tire’s sidewall will be.

### How often should you change motorcycle tires?

On average, the front tires on a typical sports bike should last 3700 miles. Rear tires, on the other hand, will last for around 1800 before you need to change it. Of course, your tires will only last quite as long if you maintain them well and get them checked on a regular basis.

### How do I know if my motorcycle tire is tubeless?

Look at the stem where it comes through the rim. If it looks like the one in Strech’s link, that’s a tubeless valve stem. If it is a bit longer, and has a nut on the outside, it’s a tube. Inner tubes have a nut on the valve stem to keep it from being pulled into the rim.

### Can you put different width tires on the same rim?

Rim Width Range. Because tires have flexible sidewalls, a single tire size will fit on a variety of rim widths. Note: Because the overall diameter of a steel-belted radial is essentially determined by the steel belts, there is little, if any, change to the overall diameter of the tire due to differences in rim width.

### How do you read the numbers on tires?

Tire Size Markings P = Passenger Car Tire. The first letter on a tire indicates the tire’s class. 245 = Section Width. Tread (mm) 45 = Aspect Ratio. (Ratio of Sidewall height to width) Z = Speed Rating. S = 112mph. R = Radial. Construction. 19 = Wheel. Diameter. 98 = Load. Index. W = Speed. Rating.

### Can I put a wider tire on my motorcycle?

So, smaller, less powerful bikes can get away with smaller, narrower tires, while bigger, more powerful bikes require larger, wider tires so that they offer adequate traction and wear, but not so wide that it ruins the handling. But putting a bigger tire on a given rim doesn’t guarantee a bigger footprint.

### Do I need Rim locks?

Yes. When you lose tire pressure the bead will unseat and spin (a lot) on the rim. If you are headed downhill with a front flat and no rim lock you don’t have much in the way of brakes. A rear flat with no rim lock pretty much means the bike isn’t going anywhere.

### Why do dirt bikes have large front wheels?

The reason why dirt bikes have big front wheel is that it climbs better over obstacles. It’s really horses (wheels) for courses. These taller wheels do roll over larger obstacles better. However the smaller contact patch on the side makes these narrow wheels more prone to slides.

### What does a rim lock do on a dirt bike?

Your rim lock is merely a clamp that holds your tire in place on the rim and is found on every dirt bike. It is designed to fit between the tire and the tube, with metal cleats on the bottom to grip the inside of the tire bead.

### What size rim lock do I need?

However, since you are looking for a rear wheel rim lock for a 19″ rim, the size you are most likely going to need is a 2.15. The 1.60 is the typical beadwidth for front wheels. Some bikes have 1.85 inch rears but for a bike of your size with a 19″ rim it is most likely a 2.15.