Last week we started a Full Informational Guide to Motorcycle Tires here is part two of that guide as promised. For a recap….. Motorcycle tires are more than just simple black rubber hoops that keep your wheels from grinding against the trail or road surface. We break them down and give you more information on them, so let’s continue with our A Full Informational Guide to Motorcycle Tires That’ll Come in Handy.
On tubeless tires, it’s also a good practice to replace the valve assemblies, as the rubber deteriorates. Tire pressure monitoring system sending units in the wheels of some high-end, modern bikes should also be checked and their batteries replaced as needed.
Tire Markings Explained
First part of this Guide That’ll Come in Handy is to explain Tire Markings. Older model motorcycles often came with inch-denominated tire sizes, such as a 3.25 x 19 front and a 4.00 x 18 rear. The first number is the tire width in inches (3.25 meaning 3 ¼ inch) and the last number indicates the rim diameter at the bead mounting surface, in inches. Most modern motorcycles use a mixture of metric and inch sizing. With these, the first number indicates the section width in millimeters, the second number indicates the aspect ratio expressed as a percentage, and the last number is the rim diameter in inches. For example, with a 120/60-ZR17 the 120 is the width, the 60 is the aspect ratio, the Z is the speed rating and the R indicates radial.
Another tire sizing method is the alphanumeric system. These are often found on cruiser tires. Every alphanumeric motorcycle tire will start with an “M.” For example, with an MT90-16 the T indicates the width (which is 130mm, the 90 represents the aspect ratio (aspect ratio is the height of the sidewall expressed as a percentage of the tire’s width) and the wheel diameter (16) is shown in inches. With a radial, there would be a letter “R” between aspect ratio and rim size. Since there is none, this is a bias-ply tire. Were this a bias-belted tire (with additional, stiffening layers over body plies), a letter “B” would be between the aspect ratio and wheel size. Tire width charts are widely available in tire catalogs and online if you need them, but stick with what you have. You have to admit having that information is pretty Handy.
Some motorcycle tires are available in a choice of load ratings for a given size. Typically this is the case with rear tires for some of the larger sport-touring machines. Make sure you choose the right tire for your bike, load, and use. Replace your tires with ones that have a load rating at least as high as the old ones for safety.
Tire Dating Explained
The next part of this Guide That’ll Come in Handy is Tire Dating and its explanation. Sorry, there is no such thing as TiresOnly.com (not the type we are talking about anyway because there is a tires only.com) so if you are a single tire, you might want to try the Craigslist Personals… Of course, we’re kidding! When tires are manufactured they have a date stamped into the sidewall. This code is a four-digit number following “DOT” on the sidewall. The first two digits indicate the week the tire was made, and the last two digits indicate the year. For example, 0414 would indicate the fourth week of 2014.
This is important because tires harden and the rubber deteriorates over time, even faster when tires are left out in the sun and weather. Most manufacturers recommend that tires be replaced when they are about six years old. However, tires should also be replaced if any significant sidewall cracks form, even if that is sooner.
Tires and/or bikes should also be stored indoors in a cool, dry place where water cannot collect on the important components and they are protected from the sun. Tires should be stored away from electric generators and motors (because ozone damages rubber) and sources of heat such as hot pipes.
In order for new tires to provide optimum performance, they should be ridden cautiously for about the first 100 miles in order for the tread surface to be “scuffed-In” and work properly. Immediately after new tires are mounted, sudden acceleration, maximum braking, and hard cornering should be avoided. This will allow the rider to adjust to the feel and handling characteristics of the new tire and for the new tire to be “scuffed-In” correctly in order to achieve optimum grip level. Track riders will scoff at this notion, but we are making this recommendation that you err on the side of caution.
As you can see, tires are more than just round loops of rubber. Not only are they the connection between your motorcycle and the road but they are the difference between having a great day riding and a day you would not soon forget. Take care of your tires and choose your tires styles wisely and if possible, don’t skimp on them. Usually, you get what you pay for.
~And as always…
~Live Free Ride Hard~
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