Motorcycle-Intelligence.com

FOUR PURPOSES OF MOTORCYCLE TIRES

So, what the heck are the four things our tires do for us?

1) They support our bike. (Alternatively, a front and rear pogo stick would create a different kind of “riding” experience).

2) Our tires transmit traction and braking forces to the road, allowing us to get up and go, and slow down or stop, exactly when we need to. (Could you imagine accelerating or braking if we had “tires” made out of, say, steel or plastic?)

3) Our tires absorb some of the surface shocks, working with the suspension to give us a smoother ride. (Even with a great suspension system, we’d have a rougher ride with old-time wagon wheels, constructed out of steel bands that were wrapped around wooden wheels).

4) And of course they maintain and change our direction of travel as a result of our steering inputs. (Hmmmmm. Pogo sticks might be better here….)

All that seems simple enough. And yet there is a bunch of design and manufacturing technology that underlies that simplicity. If you want to know ALL about it, this article ain’t for you (although you can add your knowledge at the end to flesh this out further).

But if you might be interested in a surface overview of your tires without delving into the physics, history, debates and “everything” you can know about tires, well, the upshot of the following is that over the years, tire makers have continued to improve their tires’ performance in relation to those previously noted purposes, for the sake of a better, safer (and higher selling) product. The best news is that you and I benefit from all the complex stuff that brings that about.

WHAT’S WITH THOSE GROOVES?

The grooves in our tires prevent, or minimize, hydroplaning by providing channels for water to escape beneath our tire’s footprint.

And in case a fast refresher on hydroplaning would be helpful for some, this describes when a layer of water builds up between our bike’s tire and the road. More specifically, it’s when our rain grooves cannot let enough water escape to provide a dry footprint area.

The result of hydroplaning is that our tires seem to “float” above the pavement. (A bad thing for traction-loving motorcycle riders).

More to the point, when you lose traction, braking, or steering control, it sets a scene for an unfriendly sequence in an action movie starring you. The good news is that the handling is simple: roll back on the throttle without braking or steering.

OK, so hydroplaning sets a scene for bad personal movies. Why not make the grooves as deep and wide as possible?

The extreme of that would be knobby tires, which provide a much better grip in mud, sand, dirt or gravel, but they feature a smaller contact patch, which results in less traction on pavement, while wearing much faster. Additionally, that tread pattern is noisier and creates a rougher ride on pavement, compared to the tread patterns of street tires. Glad you aren’t a tire manufacturer, yet?

Generally speaking, manufacturers are engaged in a process of rectifying the differences between deeper tread patterns to enhance safety, as opposed to simpler patterns which can be less expensive to produce, especially when simpler patterns may even provide a smoother and quieter ride. When we buy our tires, we are paying those tire manufacturing engineers to make those decisions and continue to improve their wares.

Speaking of grooves, good old racing slicks have none. They not only don’t work well in the rain, they don’t even work well on the pavement, under “normal” riding conditions. Slicks are addicted to very high, continuous speed. If they don’t get that, they don’t bother to warm up to achieve their optimum traction. Slicks are so temperamental in this way that they are illegal as street tires.

TYPES OF MOTORCYCLE TIRES

This is a larger topic than the intent of this article. But since we’ve already touched on off-road (knobby) tires and racing slicks, we might as well visit a few others.

General street tires are what have been primarily discussed in this article, which are tires for pavement that deliver good performance, reasonable wear life, and good rain handling characteristics.

High-Performance tires are for aggressive sport-bike riders who want more performance than mileage. Such tires provide better traction in high-speed cornering at the expense of a shorter life expectancy for the tires themselves. Both street and sport tires have good traction even when cold, but when warmed too much, can actually lose traction as their internal temperature increases. With production sport bikes that now blast high into the triple digit range, there is good reason to pay attention to the manufacturer’s “speed rating,” which is a tire code that indicates the maximum permitted speed that the tire can sustain for a ten minute endurance without being in danger. In other words, going over 150 mph on a tire rated for more pedestrian speeds is another way to put yourself in a personal action movie with an unhappy ending for the hero.

Touring tires are generally not designed for high cornering loads, but rather for long straights, good for riding across the country and good for longer tread life.

Dual-Purpose tires are a unique blend of very divergent requirements for dual-purpose bikes that run on street and dirt. Such tires are a compromise between street tread patterns and knobby tires and are not great at either function, but they are better than riding with a street tire off-road, and are better than riding a knobby tire on pavement. But that’s the whole design of dual-purpose bikes, they are a practical (and fun) compromise between widely disparate requirements.

WHAT ABOUT CHICKEN STRIPS?

This point is arguable as to whether it is worthy of note. But if someone points to your tires and comments about “chicken strips,” he is referring to the width of unused tread on the edges of your tires.

That width indicates the angle that you lean your motorcycle. If there is very little (or no) wear near the edge of your tires, it simply means you don’t ride as aggressively (lean as hard in corners) as some riders. So, if a sport-biker points that out to you, they are typically commenting upon their perception that you may be an inexperienced rider who is afraid to lean a motorcycle as far as it can go. In which case, he is actually not overly experienced (or mature) himself, since he either doesn’t recognize that inexperienced riders shouldn’t be pushing the limits of their bike’s performance, nor would he have an awareness that you may be a VERY experienced rider who no longer pushes his/her bike to the limit.

Anyway, the solution to such silly comments is get back on your bike and enjoy the ride.

WEAR-LIMIT BARS

When should we replace our tires? As a general rule of thumb, it’s best to replace them before they are 90% worn. (Some replace them sooner than that). Most tire failures occur in that last 10% of a tire’s tread, so just don’t go there.

Keeping an eye on the wear-limit indicators on your tires let’s us know when we’re riding into the danger zone. When our tread wears down enough, we’ll see these small raised bridges within the grooves, which is our tires’ way of telling us to put them to rest.

TIRE PRESSURE

The most routine maintenance our bike needs, other than filling it with gas, is checking tire pressure.

Our tires should be inflated to what our bike’s manufacturer recommends (check your owner’s manual, or perhaps a decal under your bike’s seat). The inflation number on the sidewalls of our tires is the “maximum” pressure for that specific tire, rather than the “recommended” pressure from the manufacturer.

If your tire pressure is too high, that life-giving contact patch is reduced, which decreases rolling resistance. However, ride comfort is also reduced, because the tires will not absorb some of the surface bumps.

If your tire pressure is too low, your tire’s contact patch is increased, but it also increases tire flexing and friction between the road and your tire. Underinflation can lead to the overheating of your tire, as well excess tread wear, lower miles per gallon of fuel consumption, and may also result in setting a scene for bad, personal movies and more gray hair since it’s also a very common cause of tire failure.

Solution to all of this: Check your tires “regularly” (every day when on a trip), and keep them properly inflated.

Eghad. The subject of motorcycle tires is much more involved than this little overview, so if you’ve got some additional items you want to add, the door is wide open to write a comment below….