March 2008 Safety Thoughts

Tires – Tread & Rubber

by Dave Hansen, Safety Officer



This month's discussion is about my one of my favorite subjects; tires.  What part of the tire provides us with that all-important item, traction?  Well, it’s not what you might think.  It’s not the tread, but rather the rubber of the tire that gives us traction.

The tread is used to provide a series of drainage passages to allow rain & moisture a way to be moved out from the contact patch where the rubber meets the road.

The rubber meeting the road is where we get our traction.  That traction is the result of friction between the road & tire surfaces.  Do we have any control over this friction that provides us our available traction?

To a certain degree, we do.  We can select tires of different rubber compounds (harder or softer) to provide varying friction qualities.  Some tires even provide varying rubber compounds across the face of the tire, using harder compounds near the center & softer compounds near the sides.  This can provide a tire that offers longer tread life for straight line travel & a softer compound with more friction for increased traction while turning.

Another way we affect the traction available is through the load on the tire.  We need to be aware of our tires’ load ratings & stay within them when we pack & saddle up to ride.  This defines our tires’ static load.  Once we’re on the bike & moving, we need to be aware that with every direction change we make, we’re dynamically changing the load on our tires.  Accelerating puts much less load on our front tire than when we’re braking.

And that changes how much traction we have available at any given time.  So too does how much we pack & where we pack it.  It all works interactively.

To learn more about how all this works together to keep us upright & on the road, sign up for the April 20 ERC Class where you’ll get both a classroom explanation & a hands on demonstration of traction, plus an opportunity to tune up your own traction control skills under controlled conditions with skilled instructors.

 Ride Safe!