Date:         Sat, 25 Dec 1999 09:56:58 -0700
Reply-To:     Kent Christensen <lkchris@USWEST.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Kent Christensen <lkchris@USWEST.NET>
Subject:      Re: Skinny Tires
Content-Type: text/plain; charset=us-ascii

Skinny Tires

Pro
better traction in snow
better traction in mud (if there's a bottom)
better traction in rain
lower cost
lower rolling resistance
better fuel economy
usually higher sidewall=softer ride

Con
poorer lateral traction in dry conditions
poorer traction in sand, bottomless mud
usually higher sidewall=flex in cornering

Fat tires
Pro
more load capacity
better lateral traction in dry conditions
better traction in sand, bottomless mud (flotation)
usually lower sidewall=less flex in cornering

Con
poorer traction in snow (flotation)
poorer traction in wet conditions (aquaplaning)
poorer traction in mud (not bottomless)
heavier
more aero, rolling resistance
more expensive
poorer fuel economy
usually lower sidewall=harsher ride

Previous poster indicated old pickup "designed that way," but frankly
wider tires were not generally available until late '60s/early '70s.
First versions were by Firestone and called "wide ovals," and were a
last gasp attempt to compete against radials with bias ply
construction tires.  They were of same era as musclecars.  Dodges with
big wings.

It's quite common in marketing to want to sell you more than you need,
and also "bigger is better" is the mantra of the
testosterone-bedeviled set.  Example: couple years ago Gatorade was
available (USA) in 16 oz squeeze bottles; they were discontinued in
favor of current 20 oz bottles that contain more than you can drink.
Vendor sells you more product/more rubber--whether you can use it or
not is not as important as selling more product and maximizing factory
throughput.

Why is skinny tire better in snow?  Square area of footprint is less,
but vehicle weighs the same (minus extra weight of bigger tire).
Therefore pounds per square inch/kg per sq m on the ground is more.
Since we're talking about Vanagons/Transporters, I almost left out the
lateral traction stuff and did leave out the "traction on tire
spinning acceleration" stuff.  I might concede that resistance to
skidding in braking may be better when tire is wider, but even this
could be offset by higher psi factor.

Why did Synchros come with wider tires?  My theories:

1.  Extra weight of Synchro equipment made cargo weight capacity
less--not politically correct, and fixed with higher load capacity
tires.

2.  Expectations: 4X4 is macho, etc.

Remember, the following are synonymous:  flotation, aquaplaning,
skidding.  Unless you're crossing the Sahara, or farming and don't
want crop damage, you do not want flotation.

Tall and skinny beats short and fat nearly every time.  Tires, that
is.