Date: Sat, 14 Mar 2009 14:25:08 -0700
Reply-To: Scott Daniel - Turbovans <scottdaniel@TURBOVANS.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Scott Daniel - Turbovans <scottdaniel@TURBOVANS.COM>
Subject: Re: Tires - Why oh why NOT?
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there's a lot more that goes into when a tire will fail than just wheel
diameter, and aspect ratio of the tire.
( though you would think naturally that 'less tire'.........shorter distance
from wheel rim to road, my somehow inherently be stronger )
why I'm responding is mainly to ask you what you mean by staggered rims.
You must have 50 series ( aspect ratio ) 16 inch tires on one end, and /55
something on the other end.........
but that has nothing to do with the wheel rims really.
so what are you trying to describe ?
I will say..........that very much so, in 2WD rear wheel drive there is
considerable handling feel and cornering stability to be gained by dedicated
front and rear size tires, and sometimes dedictated front and rear wheel
sizes and wheel widths.
check out any modern 2WD rear wheel drive performance car ..........ferrari,
porsche, coverette etc.
if the front tires are say 245/55 R 17 .....
the rears will always be a lower aspect ratio, but a bigger cross section
number ( the first # in the tire size ) ....
a car with 245/55's on the front, might have 255/50's on the rear for
example.
compard to identical tires and wheels front and rear, I'd say there is a
solid 20 % gain to be gotten using dedicated front and rear tire sizes in
terms of handling feel and cornering stability. The affect is quite
noticeble,.
if there is anyone out there doing this in 2WD vanagons.........great to
hear, Cause I don't find hardly anyone who knows about this .....
I also point out that all motorcycles have larger rear tires, and
traditional racing cars like formula one and Indy cars........same thing
.......
you always want 'more tire and wheel on the rear' .
And please, don't anyone say adding a rear anti-sway bar is the same thing
like someone did 8 months ago...........roll rate, and rear roll rate, is a
whole other story, and does not have the same affect.
So......are there many vanagon owners aware of this.
last paragraph..........here's how my 85 Weekender with 15 inch south
african steel wheels, and Michelin Agilles 205/65 R 15 C tires handles :
It obviously rolls a little easier ( less rolling reistance ) than ordinary
LT or C rated 14 inch vanagon tires and wheels. It goes in a straight line
very, very well, almost steers itself going straight. When I put it into a
turn ............the turn in is fairly crisp ........decent turn in for sure
........
and it takes a set in a corner nicely...............but if you push it
..........it just goes into terminal oversteer. There's no cornering force
to 'lean against' .........so nice, at first, feels like a boat easily with
any corning force at all. Kind of a blend of strong understeer with the
feeling it'll slop over to oversteer if you push it, so you stop trying to
generate any cornering force pretty early.
On the other hand............my 83 Westy that's for sale.........14 inch
alloys front and rear ...........LT tires front and rear, but the rear ones
are larger ........bit taller, plus wider some. This van feels and drives
pretty much like a sports car. Feels nimble and tossible.
Turn-in isn't so crisp, but it takes a good set in a conrner nicely, and you
can 'push' against it. As I push it harnder in steady-state cornereing
........it repsonds, there's still a nice gentle understeer.......but it's
much, much more in the direction of neutral handling compared to my 85 with
same size front and rear wheels and tires. Whether 'pushing' a little in a
corner at 35 to 45 ......or jamming big sweepers on the freeway at
75............very steady cornering feel that you can 'push into' with good
feedback, and neutral handling with a small amount of gentle understeer for
predictability's sake........just what you want.
I won't mention I have raced cars and motorcycles as far back as the 60's
and I might have an idea what I'm talking about in terms of vehicle dynamics
and handling feel.
Bottom line is, .........with identical front and rear tires and
wheels.........all you've got to tune the handling with is the tire
pressures........
and that helps, it matters for sure ( more psi in the rear always, per stock
btw ) ........but it won't get you anywhere near what dedicated tire sizes,
and wheel rim widths will. ....in terms of straight line tracking, good turn
in, and responsive cornering feel and abilities.
For those that don't realize that vanagons have very sports car like
suspension ..........it does. A Mid-80's Mercedes 450SL has the same
thing.......A-arm front suspension, traiing arm rear suspencion, coil
springs, front anti-sway bar .............and the Benz has a small rear
anti-sway bar, but the Vangon has rack and pinion steering.......mercedes
didn't get that until the 90's on most of their cars. Vanagons can handle
well, if they are properly tuned to do so, and understood well.
scott
www.turbovans.com
----- Original Message -----
From: "Zeitgeist" <gruengeist@GMAIL.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Friday, March 13, 2009 5:52 PM
Subject: Re: Tires - Why oh why NOT?
>I don't know all that much about tire technology, but wouldn't my 16" 50/55
> (staggered rims) series passenger tires be less prone to failure issues
> than
> a 14" 70 or 75 series passenger tire?
>
> --
> Casey
> '87 300TD
> '94 100CSQ Avant
> '89 Bluestar
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