Are Your Tires Tired?

By: Graham H


It’s the perfect time of year to check out those rubber hoops to make sure your tires are grippin’ and not slippin’ on cold, wet, winter riding surfaces. For motorcyclists, it may not always be glaringly obvious when your tires are beat, so here are a few key indicators to let you know when you need new tires on your bike. Barring anything obvious like a punctured or damaged tire, the first indication a rider usually gets that his or her tires are tired is a change in the feel of their rubber on the road or riding surface. Worn-out motorcycle tires will feel sloppier in the corners and lose traction more easily in twisties that you could blast through in the past. If you are feeling a difference in the performance of your bike, take a close look at your tires for telltale signs. If you see any fabric or tire cord exposed through the rubber, your tire is not safe to ride on. If you still have a good layer of rubber, the next step is to check out the tread depth.

Checking Tread Depth
Most tires in production today have little raised rubber bars built into their design, called tread wear indicators (TWI), that show you when your tread depth reaches the recommended replacement threshold (usually around 1.6mm [1/16th inch] for street tires, off-road tires are more subjective). These indicators are generally made obvious on your tires’ sidewalls with arrows pointing to their locations or the initials “TWI” pointing to these bars. Your tread wear indicator looks like a raised band of rubber inside of the tread groove, and usually wraps all the way across the width of the tire. When your tread is worn down to the level where it is even with this raised band, this means it is time for new tires. If you aren’t looking for these indicators, they may not be obvious to you, so go take a look and see if your tires are equipped with raised bumps between the threads.

The Penny Test
If you can’t locate any tread wear indicators on your motorcycle tires, not to worry. You can use a sophisticated, high-tech electronic tread wear indicator… or you can check the depth of your tread with a penny! Just place a penny upside down into your remaining tread groove, and if you can see the very top of Lincoln’s hair, it’s time to shop for a new set of motorcycle tires.

Uneven Tread Wear
So your tires passed the tread-wear-indicator or penny test... you’re good to go, right? Not quite. Due to the curved surface of your motorcycle tires, the patch of rubber that actually contacts the pavement at any given time changes. When you’re cruising in a straight line, only the very center 1-4” strips of your tires are touching the ground. When you lean into a turn, the areas closer to the edge of your tires begin to take on the weight and forces of your bike’s travel. Often, this can result in uneven wear. The most common form of uneven wear on motorcycle tires is a condition called “flat spots.” Flat spots are typically in the central strip of the tire, where you contact the pavement in a straight line. Flat spots can also form on the edges of your tires from leaning into your turns since we each lean at about the same angle every turn, even though every turn is different (we get comfortable with certain corner entry speeds and angles, and our muscle memory tends to favor particular angles over time). These flat spots occur more quickly in underinflated tires, but are almost inevitable in most types of street riding. If the profiles of your tires are becoming more and more squared-off, you are getting flat spots and should start thinking about some new hoops.

Another form of uneven tire wear is known as “cupping” or, more accurately, “scalloping.” This is when the leading edge of each tread groove becomes rounded and dull, and the trailing edges of each groove take on raised, sharp-looking edges. Scalloping is a result of the extreme forces being exerted on the tire during hard cornering and braking. You can demonstrate this effect by taking a brand-new pencil eraser and dragging it hard in one direction across a table. You will see how the leading edge takes the brunt of the force and dulls, while the trailing edge retains its sharper edge. Some riders worry that scalloping is an indication of poorly adjusted suspension components, but this is not the case. Scalloping just means that you have really been tearing up the twisties, but it also means that it is time for new rubber.

Checking the Born-On Date
Even if your tires are groovy with no uneven wear and plenty of tread, there is one more factor to consider, especially if you purchased a used bike with tires already on it. That factor is age. If you didn’t buy your tires or you can’t remember when you did, check for the production date. Among the numbers stamped on your sidewall, one of them indicates the “born-on date” for your tire. It won’t look like a standard date, but rather a simple three- or four-digit code like “4702.” The first two digits indicate the week the tire was made, and the last two digits indicate the year. For our example, that tire would have been made during the 47th week of 2002 (tires made prior to 2000 have only 1 digit for the year). The general rule-of-thumb is to avoid riding on a tire over six or seven years old. For example, if you see the number 1910, your tire isn’t really over 100 years old, it means it was born during the 19th week of 2010.

Check out our huge selection of tires for all kinds of powersports machines at Motorcycle Superstore. We have a massive assortment of tires in stock, and with our Preferred Installer Program, you can have your tires shipped straight to a professional tire installer in your area.

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