Date:         Wed, 26 Feb 97 10:03:05    
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         mdstockr <mdstockr@neo.lrun.com>
Subject:      Re: Lighter tyres for lighter steering? 

As a general rule, this statement is correct for comparable tire designs.

But, the tire's contact patch "area" does not remain constant for different 
tire designs.

The contact patch area is a function of the spring rate of the tire for a 
given inflation pressure.

Contact patches can have different contact pressures for different tires 
designs.  And, for a given load, different pressures result in different 
contact areas.  Reinforced tires tend to have a higher spring rates and 
smaller contact patch areas than comparable standard tires under the same 
load.

Also, the contact patch is dependant on the kinematics of the vehicle's 
suspension.

Different suspensions will induce different tire camber changes, which 
directly relates to the shape of the tire's contact patch.  For example, you 
do not want to have a wide tire on an old VW with rear swing axles.


--- On Wed, 26 Feb 1997 08:49:59 -0600  JonR <jonreed@earthlink.net> wrote:

>an interesting side note...
>
>	the Contact patch of the tire in this size range(185R-14 to 
205/70R-14)
>remains constant...
>
>	you go to a "wider" tire the contact patch is  wider from side to 
side,
>but shorter front to back.  This in turn gives you more resistance to
>side loads (handling "feels" more precise...)
>
>	Learned this interesting little fact at a Michelin Tire school...
>
>			JonR

-----------------End of Original Message-----------------

________________________________________________

  Michael Stocker <mdstockr@neo.lrun.com>
  North Canton, Ohio, USA     Time: 10:03:05 AM
  LiMBO / GASS                Date: 2/26/97
  1989 Audi 90 Quattro
  Wanted: Nice 1968->? bus or Westi
  Previous VW's: '66-T3, '67-T1 & '70-T2 Westi
________________________________________________