The Care and Feeding of Motorcycle Tires

by

Judy

Why Care?

Your tires need regular attention. They are the only connection between you and the road, and simple things like tire pressure become much more critical than the pressures in your car tires. Tire wear is the removal of rubber from your tire as you use it.

Under Pressure?

The single most important thing you can do is check your tire pressure. Do it often, before each ride! (Or at least once a week). While you’re at it, do a quick visual inspection checking for cuts or sharp objects embedded in your tires. What should the pressure be? Note that the pressure stamped on the sidewall of the tire is a maximum pressure…one you’d run with the bike fully loaded and/or with a passenger. Many newer bikes have a sticker on the swingarm that lists the tire pressure, or, you can find it in your owner’s manual. Typically, the pressure used for solo riding is about 4 psi less than the maximum value stamped on the sidewall. Increase the pressure by 3-4 psi if you have a lot of luggage or a passenger but never go above the maximum allowable pressure. (NOTE: Always measure your tire pressure when the tires are cold.)

Cap It!

Valve stem covers are an important part of the sealing system. Use them! Replace them if they are cracked or missing. In addition to keeping out dirt and moisture, the valve caps help keep air in. The centrifugal force generated by wheel rotation can be enough to open the valve core, allowing air to leak out. Use valve stem caps with rubber gaskets in them.

Worn Out?

There are obvious signs your tires are worn out…bald, or the wear bars are showing. In addition, your tires may become “cupped” or scalloped. What does it look like? Look at the tread off-center of your tire. Cupping produces a deeper valley at the leading edge (direction of rotation) of the tread, and a peak at the trailing edge of the tread, producing a scalloping effect. This doesn’t mean anything is wrong with your bike, but it does mean the tires need to be changed. the picture below shows typical wear patterns. Click Here to see a picture of this type of wear.

Flat Spots?

You can also have flat spots. Look at your tire from the front (for the front tire) or from the rear (for the rear tire). Is the point where you’d be leaned over in a turn on your tire flattened out? Instead of a nice, even, rounded profile, is there a flat part off the center of the tire on either side? If so it’s worn out.
Or, you could have a flat spot on along the center of the tire. This is where the center of your tire is flattened out from lots of straight line highway riding. It’s also referred to as a “squared off” tire. If the center of your tire is flattened out, even if there is sufficient tread left, the bike won’t lean into a turn properly. Time for a replacement. Click Here to see a picture of this type of wear.

How Old Is That Thing, Anyway?

Old tires may show signs of age by evidence of cracking of the sidewall of the tire, also referred to as dryrot. A tire that’s barely been used can dry out just from age and exposure to the sun, so even if there’s lots of tread left, if there is evidence of cracking, it’s time for new ones. Generally, once tires are over three years old, they have probably started to get hard, even if the sidewalls haven’t cracked yet. A hard tire won’t conform and grip the road like it should.

When Was Your Tire Made?

The manufacture date is in a code printed on the sidewall. It will be the last four digits (for tires made in the year 2000 or later) in a string of letters and numbers starting with DOT. The first two digits are the week of manufacture, and the last two digits are the year of manufacture. For example, if it says DOT817AD472200, look at the last four digits. 2200 means that your tire was made in the 22nd week of the year 2000. Tires manufactured prior to the year 2000 will have a three-digit code. For example,
DOT733AC297, means (looking at the last 3 digits 297) that your tire was made the 29th week of 1997. Or, the 29th week of 1987! Yikes! I think that’s why they went to a four-digit code! Anyway, if your tires are much over three years old, consider replacing them.

Can I Mix and Match?

That might work for your wardrobe, but not your tires. In general, the brand and model for the front and rear need to be the same. In some cases, the tread pattern is similar enough to mix. Some Pirelli and Metzeler tires, for example, are compatible. It would be best to check with a reputable dealer to be sure. Mixing two tires whose tread patternaren't compatible can have deadly results. They won’t work properly together. Tires are made one of two ways: Bias ply or radial. Some bikes that come equipped with bias ply tires cannot be fitted with radials, and vice-versa. Again, check with your dealer. NOTE: (NEVER mix a bias ply with a radial!)


Size Does Matter!

Of course, the size tire your bike needs will be in the owner’s manual, but it’s also on the side of the tire. Didn’t know you could read so much off the sides, huh? The code will look something like this:
120/70 ZR 17. The width of the tire is 120. 70 is the aspect ratio, meaning that the height of the tire is 70% of the width. Z is the speed rating. R is for radial, and 17 is the wheel size. There are several speed ratings for motorcycle tires: J, N, P, S, H, V, and Z are rated for 62, 89, 94, 112, 130, 149, and 149+, respectively. It’s always a good idea to replace the tires with the same size as what came on them stock. You can usually go up one size in the rear, but much more than that will compromise the bike’s handling characteristics. Or, it may not fit, and will rub on the swingarm. In this case, bigger isn’t better.

New Tires Are Slick!

When you have new ones spooned on, take it easy for several miles to scrub them in. New tires are coated with residual mold release which makes them very slippery. Easy on the throttle and brakes at first, and gradually increase your lean angle. This will allow you to wear off the slippery coating. Once all that shiny stuff is worn away, you’re good to go!

Can I Plug or Patch it?

I just got a nail in my new tire! ##$%^(%^&!! You can plug or patch the tire long enough to get you to the shop for a replacement. This is a topic of great controversy. You’ll get a different answer depending on whom you ask. Personally, I won’t do it. I figure a couple hundred dollars for a new one is cheap insurance. Plugs sometimes don’t stay put. Once a tire is plugged or patched, the speed rating is no longer valid. You ask a lot more of a motorcycle tire than you do a car tire.

Respect Your Tires!

The size of your tire’s contact patch that’s connecting you to the road is only about 2 inches wide! So make sure they are up to the task!

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