The Key Parts of a Tire

The wide world of motorcycle tires can be bewildering even for the experienced biker. With so many options to choose from, how do you go about finding the right fit for your motorcycle? This guide aims to demystify the process of buying motorcycle tires.

Tire Anatomy

Let’s start with some basic definitions. Every motorcycle tire has the following key components.

• The tread that grips the road, providing traction.
• The sides, or sidewalls, that give support and handling.
• The bead on the edge of the tire that grips the rim.
• The valve stem that controls inflation.
• The rest of the tire body is called the carcass.

Size Formats

Many motorcyclists ride around completely unaware of their bike’s tire size. After all, it doesn’t come up until you need to purchase new tires. Thankfully, it’s easy enough to figure out your tire size: you can either check the specs in your owner’s manual or simply take a look at the numbers printed on the sidewalls. There are three common formats for sizing.

Metric Sizing

Metric is the most common size format. Tires with metric sizing will have three numbers printed on the sidewalls, the first being the width (in millimeters), the second being the aspect ratio (the height of the sidewall as a percentage of the width), and the third being the rim size (in inches). Between the second and third numbers, you may find the letter R or B, indicating whether the tire is Bias Ply or Radial.

Alpha Numeric Sizing

Alphanumeric sizing is often used for cruiser motorcycles. This string of letters and numbers will need to be decoded in detail with a Street Tire Size Conversion Chart to determine the width and rim size.

Inch Sizing

Inch sizing is mostly used for dirt bikes. Look for two numbers printed on the sidewalls: the first will be the width in inches, followed by the rim size in inches. Inch sizes can run all the way from 2.75 inches to 6 inches.

Load and Speed Rating

Just because a tire is the right size doesn’t mean it will work for your motorcycle, so don’t make the mistake of overlooking the load and speed ratings. Choosing tires that can’t keep pace with your motorcycle or carry its weight can lead to tire failure.

Tires using both metric sizing and alphanumeric sizing will be printed with a number representing their load rating and a letter representing their speed rating. Look up the load rating in a motorcycle tire load index to determine the amount of weight your tires can carry, and consult a speed rating chart to determine the maximum sustained speed capability of your tires.

Radial Vs. Bias Ply

Motorcycle tires are constructed using one of two methods. 

Bias ply construction uses fabric cords laid in a criss-cross pattern to create stiff sidewalls that can bear heavy loads. Bias-ply tires are often preferred for heavyweight machines like cruisers and touring motorcycles. 

Radial tires, on the other hand, use alternating steel belts for thinner and more flexible sidewalls. Radial tires are designed for better steering control and optimal performance at high speeds, making them ideal for standard motorcycles and sport bikes.

Tube Vs. Tubeless

Tube or no tube? This is a common question when it comes to motorcycle tires, and the answer is that both options have their place. If your motorcycle has spoked wheels, it will probably require tubes. If your bike has cast wheels, mag wheels, forged wheels, or billet aluminum wheels, then you can go tubeless. There are some exceptions to this rule, and you can always add tubes to your tubeless tires if your bike wheels require them.

Tubeless tires have many benefits: they are more lightweight, they run cooler, and they are easier to repair than tubed tires. However, tubed tires have the advantage when it comes to handling rough terrain, and many riders prefer the classic style of spoked wheels. Keep in mind that when purchasing tubes, you will need to make sure they are compatible with your tires and valve stems.

Are you looking to buy a motorcycle? Check out the available models at Windy City Motorcycle Company. We serve those in Detroit, Michigan, Milwaukee, Wisconsin, and Chicago, Illinois.