Rolling Along to Our

Destination . . . Friendship


In an effort to help all the riders out there in our wet part of the country I would like to post the following article so that all may take a moment to stop and read up on wet road riding. Most of us are pretty good at this because we get so much of it, but I know that some of us could learn just one item that might save a life…maybe your own….


Water escapes from under a tire by squishing out sideways along lateral grooves in the tread. A good rain tire will have deep angled grooves that point out towards the sides of the tread. The good news is that narrow motorcycle tires have a relatively long, narrow contact patch that slices through puddles. The bad news is that today’s wide, low profile motorcycle tires (which handle so much better in the dry) are more likely to hydroplane over standing water. Roughly speaking, the typical low profile radial car tire will start to hydroplane in 1/2" of standing water at about 60 mph. The wider your tires, the more likely they are to hydroplane at the same speed-something to consider when you’re thinking, "Hey, maybe I could fit a 170/60-17 on the back instead of that old-fashioned 140/80-17"

And while we’re talking tires, remember that a worn tire has shallower grooves which won’t let the water out as easily. One of the advantages of a new tire is deeper grooves, and therefore an increased hydroplaning threshold.

It’s also important to keep your tires pumped up to correct pressures. An under inflated tire encourages a big ripple to form ahead of the contact patch, and traps water at the edges. A properly inflated tire has a better chance of pushing down through the water and maintaining a grip.

Traction Control

Once you’ve had your tires do the moonwalk on a rain-slicked off ramp, you can get pretty paranoid about a fall down every time it starts to pitter patter. Obviously, there are many areas of relatively good traction, and a few rally slippery areas. That’s a clue that the slipperiness is caused by something more than just rainwater. The truth is, clean wet pavement has something like 80% of the friction of clean dry pavement. Of course, the critical word is clean, and

Of course, the critical word is clean, and pavement rarely is that. Passing vehicles drip all sorts of lubricants on the surface, including diesel oil, antifreeze, chassis grease, brake dust and rubber particles. Note that antifreeze is so slippery that liquid cooled race bikes must use only water in their radiators. In addition to those slippery vehicle droppings, people toss, dribble and spit a variety of lubricants out the window, including cigarette butts, hamburger wrappers, french fries, ice cream, pizza, soda pop, snooze juice and used diapers, to name just a few. That road glop doesn’t simply evaporate. Most of it gets squished into particles and mashed into the pavement. A little moisture mixed with that glop can create a slippery emulsion which is what really reduces traction. That’s why the road seems so treacherous after just a little mist or morning dew. It’s the sloppery goo, not just the water. Now, think about this: the only really good pavement cleaner is a steady downpour that lasts longs enough to float that accumulated slimy stuff into the gutters. That offers us two lessons: First, the longer it’s been since a good rainstorm, the more slippery the pavement is likely to be. If it’s been dry for awhile, you can actually see the slime floating away during the first half hour or so. Secondly, the pavement will be most slippery when it first starts to rain, especially if it’s just a little sprinkle or some morning mist. Those lessons are especially important for riders who live in "dry" areas and don’t get a lot of rain riding practice.

Once the road glop gets washed away, both asphalt and concrete paving can have relatively decent traction in the rain, with some obvious slick exceptions. Shiny spots such as plastic arrows, steel plates, grated bridge decks or railroad tracks will be treacherous when wet. Loose objects such as leaves, cardboard or flattened pop cans will be even more hazardous when damp. And trucks or busses that dribble oil will continue to dribble fresh supplies of oil on tip of the rain water.

So, take extra care when the rain starts, don’t let your guard down for a second…it could be your last.


see ya down the road

Jim Townsend