Without meaning to make a bad pun, there's an awful lot riding on your motorcycle tires. Poorly maintained tires compromise the bike's handling and your safety to a degree that can't be overstated, so making sure they're in good condition is one of the most important tasks associated with motorcycle maintenance. Fortunately, it's a job that's quick, easy and requires nothing more than a tire pressure gauge and a Lincoln head penny.
All tire maintenance starts with a thorough visual inspection, and yes, that usually means getting down on your knees so you can get a worm's eye view of it. The first thing you'll want to examine is the tread depth. A bald tire can toss you down the road faster than it takes to read this sentence, especially if the road is a little wet. They're also more prone to puncture, so there's no compromising here. Taking "one last" ride on a worn out tire can have dire and very expensive consequences.
Because "bald" is sometimes open to interpretation, "whadda ya mean that's bald, that things got another couple of thousand miles left in it," the tire manufactures and the DOT have come up with two ways to determine just how bald a tire is. To eliminate the guess work all current DOT approved tires incorporate wear bars that run across the tread to provide an easy to read visual indication of the tread condition. When the tire is new the bars are invisible, as it wears they become more prominent and eventually become unmistakable. As a rule, once the tread reaches the wear bar, its shot and should be replaced before the next ride.
In some instances the wear bars might not be readily apparent. If you can't find them look for a small repeating pattern on the sidewall, a small triangle perhaps, or if you're running Michelin tires a tiny representation of the Michelin Man. The symbols indicate where the wear bars are located in the tread, or better yet consult the tire manufacturer's web site.
As an alternative you can always measure the tread depth. Normally a tire is considered worn out when the tread depth is 2/32 of inch deep. This number varies slightly between the tire manufactures, and some of the motorcycle manufactures supply their own specifications as do the states, but in general the 2/32 of an inch number should keep you out of trouble. Of course reading a ruler marked in 32nds can be tough, especially when you're on your hands and knees peering at a tire.
Tire depth gauges are available, you can find them at most anywhere you can buy a tire, but an easier solution is to stick a penny in the tread. If all of Lincoln's head is visible the tire is past it's sell by date. If a portion of Abe's head is covered up you're good to go. By the way if you're wondering why I used the 2/32 of an inch instead of just saying 1/16, it's because in the US, using 32nd's to describe tread depth is a convention that goes back to the inception of the rubber tire. The rest of the world describes tread depth in millimeters or nominal fractions.
Besides inspecting the tread depth, keep an eye out for any foreign objects, primarily sharp ones that will create problems at a later date. Often a screw, nail or other road-hazard can be removed before it does any real damage, if you catch it in time. And if the tire does start leaking when you pull out that roofing nail, well at least you can comfort yourself with the knowledge that it happened in your driveway while the bike was parked, as opposed to it happening at 65mph on the interstate. Last but not least, check the sidewalls for damage, look for bulges, splits and cracking and as you'd expect, replace any tire that's questionable.
Once you're satisfied with the tire's physical condition check the tire pressure(s) and adjust them accordingly. My preference is to use an electronic digital gauge, they're inexpensive, dead accurate and easy to read, and don't forget that tire pressures are always adjusted with the tires cold.
The bottom line here is that if you take care of your tires, they'll take care of you. A little maintenance, the foregoing should take about ten minutes a week, provides an extra margin of safety and reliability. And most importantly keeps you on top of your tire wear. Because when it comes to tires, what you don't know is what hurts you.
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