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Since 1999, the #1 Motorcycling Magazine for Women and the Men Who Ride with Them









A Tire Tell-All

Get to know your tires

By Athena Ransom
5/22/2008

How do I read a tire sidewall?
Sidewalls have lots of usefull information on them. The manufacturer places this information on the tire for the dealer who sells them, the technician who installs them and the consumer or the person who normally maintains them. Sidewalls provide the manufacturer's name, size expression, direction of rotation, load rating and the U.S. DOT serial date code as well as the intended rim application and use.
Tires are one of the easiest parts of a motorcycle a rider can maintain on her own. This woman is riding the Suzuki Boulevard S40.
Tires are one of the easiest parts of a motorcycle a rider can maintain on her own. This woman is riding the Suzuki Boulevard S40.

What do all of those numbers mean?
A tire sidewall is read like a book, from left to right. On the sidewall you will normally find the manufacturers name at the top center of the tire sidewall, to the right the first set of large numbers that refer to the tire size, for example 200/60-16. The first number is the width of the tire in millimeters; the second number refers to the aspect ratio (percentage of height to width); the third number refers to the diameter of the wheel in inches.

To the right of that number you will find another three digit group in the same style font, for example G3H. This is the load index and speed symbol. These numbers are referred to as size expression and are used to designate tire to rim fitment.

A tire chart - provided by Dunlop
A tire chart - provided by Dunlop

To the right of that normally is the patent number and the U.S. DOT Serial Code. The DOT Serial Code depicts the date of manufacture. The first two digits indicate week of year tire was manufactured and the last two digits indicate the decade and year the tire was manufactured. To the right of that are the words front or rear indicating the intended use of tire, followed by the rotation symbol which denotes the direction of rotation for when the tire mounted. The rotation symbol (arrow) should be facing the front of the vehicle.

Next you will find manufacturers style name or brand unit number. You will also find on the sidewall the composition of tire, load range and maximum load rating at recommended PSI (pounds per square inches). The PSI on the sidewall is the maximum amount of pounds per square inch of air allowed in your tire; it is not the recommended amount of air in your tire. Always refer to your motorcycle's owner or service manual for recommended PSI of air in your tire for the best wear and duration at safe speeds.

What is the little colored dot on the side of my tire?
Tire manufacturers place a colored dot on the sidewall referred to as a "harmonic marking." This allows match mounting meaning the colored dot goes in line with the valve stem when mounted.

Tube vs. tubeless tires: what's the difference?
Tube tires are used for spoke rims and tubeless are used for a "mag" style rims. A tube is never to be used in a mag style rim because the air between the tube and the tire has no place to escape and will create a "soft spot." This will create a hazardous or unsafe riding condition.

A mag style wheel that goes with a tubeless tire.
A mag style wheel that goes with a tubeless tire.

Another style of mag wheels - this one from a stock Harley-Davidson Rocker.
Another style of mag wheels - this one from a stock Harley-Davidson Rocker.

How often should I check air pressure and how important is it?
Tire pressure is extremely important. Air has a way of slowly seeping out of a tire through the microscopic porosity of the tire itself. That's why you'll notice a decrease in tire pressure after your motorcycle has been parked for many months. A good rule of thumb on checking tire pressure is this: If you ride several times a week you should check your pressure once a week. If you ride less often, check it before you ride every time. Safety is the first reason to do this; many accidents could have been prevented if the rider ensured his or her tires were properly inflated. The second reason to check tire pressure is to maintain the wear and life of the tire.

You should always do a visual check of your tires before a ride to make sure they're in rideable condition. Check the tread. Make sure there are no cracks. Exposure to the sun causes tires to crack and dry out, especially the sidewalls. Make sure you've not run over a nail, or that any road debris is stuck in them. Check to see if the tire is wearing evenly. If there appears to be some cupping or the tire is wearing unevenly, this could be an indication that something else is wrong, like a suspension problem. Many of us forget to actually look at our tires before getting on the bike. It's the easiest way to tell if something is askew.

An example of a spoke wheel.
An example of a spoke wheel.

Does Fix-a-Flat work?
According to Fix-a-Flat's Web site, the product is not intended for use with motorcycle tires. There are, however, tire sealant products you can carry with you designed for motorcycle tires. This one is for tubeless tires only: Stop and Go Tubeless Tire Plug Gun Kit. It sells for $49.95 and is available at WhitehorsePress.com.

To fix a tube tire, the tire will have to be removed from the rim. Here's a product that can repair both tube and tubeless tires, although it does not contain tools to remove a tube tire from the rim. The Tire Pro Repair Kit costs $24.95 and is available at CruzTools.com.

For a good selection of flat tire fix kits, visit StopNGo.com.

Performance tires: Should I get them, or do stock tires work OK?
Motorcycle and tire manufacturers do research and development on tons of tires and the recommendation is that stock tires work for normal (intended) riding conditions for each application, i.e. off-road, street or race. If the bike is used for purposes other than originally intended, an upgrade may be necessary. When purchasing tires, do not mix radial and non-radial tires as this could create handling and stability issues. It is good practice to stay with the motorcycle manufacturers recommendations regarding which tires to use.

How do I know when I need a new tire?
Aside from maintaining proper tire inflation, you should be mindful of how much tread you have on your tires. A penny will give you an idea of how much tread is left. You've probably heard this example used before. Stick a penny in the tire tread with Lincoln's head down. If you can see the top of Lincoln's head the tread is worn close to or over the legal limit. The legal limit for tread depth is two thirty-seconds of an inch. The top of Lincoln's head to the top of the penny is about two thirty-seconds of an inch. If the tread covers part of Lincoln's hair, your tires are probably OK.

Tire manufacturers provide lots of helpful information. For more information visit these Web sites:
DunlopMotorcycle.com
MetzelerMoto.com

Athena Ransom owns Vagabond Chopper Company, a motorcycle shop in Pompano Beach, Florida, where she repairs and builds custom motorcycles. Her bikes have been featured in numerous motorcycle magazines and bike shows. She has been riding and wrenching on motorcycles since 1994 and is married with two children. If you have questions, call Athena at her shop at 954.360.0075, or email at vagabondchickie@aol.com. You can also post a comment or question or comment below.

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