Date:         Mon, 28 Apr 2003 09:30:26 -0600
Reply-To:     John Rodgers <j_rodgers@CHARTER.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         John Rodgers <j_rodgers@CHARTER.NET>
Subject:      Re: 185 tires on alloy wheels
Comments: To: Willolyn99@AOL.COM
Content-Type: text/plain; charset=us-ascii; format=flowed

Airliner tires, in their tread cross-section - are basically round as in
the chord of a circle. But  deeply and narrowly ribbed. The sheer weight
of the airplane flattens the cross section but in doing so puts all
those ribs tightly against the surface of the asphalt. The ribs also
force any  water under the ribs into the deep grooves between the ribs
thus allowing the water a place to excape the pressure of the wheel,
thereby reducing the tendency to hydroplane. When an airliner tire first
contacts wet pavement on landing the center two ribs contact first,
cutting through and displacing the water and as the weight continues to
settle more and more on the tire, more and more ribs contact thus
displacing more and more water reducing hydroplaning tendency. And those
narrow ribs with that tremendous weight on them increases the friction
tremendously to prevent skidding. And of course modern airliners have
anti-skid brakes as well to further enhance safety and reduce the
tendency to skid in hydroplaning.

John Rodgers
88 GL Driver

Bill Marshall wrote:

>Hey, not so fast -- I want to disagree that the wider tire is automatically
>better traction.  The narrow tire concentrates the weight of the van over a
>smaller area, making it less prone to hydroplane in wet conditions and less
>likely to 'toboggan' over the snow.  They dig in.  On dry pavement, or in
>loose dirt and sand, the wider may be better.  All the guys I used to know
>who had wide tires on their Camaros used to swap them for  narrower snow
>tires in the winter.
>
>Think back to physics class.  The harder you push down, the more force it
>takes to overcome friction.  More force per square inch.
>
>Bill Marshall
>85 GL Tiico "Pandora's Box"
>Aurora, IL
>
>
>