Date: Sat, 11 Jul 2015 11:18:33 -1000
Reply-To: "SDF ( aka ;jim lahey' - Scott )" <scottdaniel@TURBOVANS.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: "SDF ( aka ;jim lahey' - Scott )" <scottdaniel@TURBOVANS.COM>
Organization: Cosmic Reminders
Subject: Re: Why new tires should go on the rear.
In-Reply-To: <CAFdLW6kknXLjvGk-Ev_KOo1LnNcr60TK1hdiToJfb9xjh2L2MQ@mail.gmail.com>
Content-Type: text/plain; charset=utf-8; format=flowed
Well...it depends.
Generally ..rear wheel drive two wheel drive vehicles should have the
tire /wheel combination with the most stability and traction on the rear.
The reason being ...and you can try this yourself on your vanagon
...just with tire pressures ..
Assuming the same type size and age front and rear tires ..
set the rear tire pressures to say 30 psi and the fronts to 45 .
Your van will be all over the road, have a bad tendency to oversteer,
and will 'jump around' on bumpy surfaces requiring constant steering
correction ..on bumpy paveed surfaces .
reverse the pressures and , sure if you have too much front-rear tire
pressure difference you'll have a badly understeering vanagon.
Some vanagons are just awful understeering pigs. They don't need to be
that way.
also ...'new tires' do not have the very most stability and traction.
In showroom stock car racing ..where the car has to be exactly as it
comes from the factory ( with maybe a roll bar added) and tires OE grade
or style ..
brand new tires are shaved ...about 1/3 to 1/2 of the tread is
intentionally removed.
If front and rear tires are different you have to be careful.
I've seen two brand new tires with very tall squimy tread on the back of
a 2WD Rear wheel drive Volvo cause the car to be all over the road
..this due to much from front stabilty and tranction than rear.
Swab those new tires , in That Particular Case to the front ...car was
fine ..with the normal 'slight understeer.'
FWD cars are a whole special case .
to give you an idea ....in rear wheel drive performance driving engine
power is used to induce 'rotation' going into a steady state curve, like
on a race track. This can be also induced with trail braking..
the point being that drive train dynamics affect the back end ...while
steering affects the front end.
In an FWD car this advanatage is basically not there.....and ..on a race
track to performance drive a FWD left foot braking is used in some
portions corning.
Thankfully Vanagons are not FWD. I gave up on them years ago . Mostly
when pushed they understeer. Though modern FWD manage to transend this
beautifully. Even Lotus came out with a FWD performance car, though I
don't think they offered that model for very long, nor do they have one
now.
All serious performance vehicles are RWD or AWD ...cars and motorcycles.
anyway ...check out the tire and wheel sizes on all modern performance
cars, especially 2WD ones...the rear always has 'more' and as I've said
many times Vanagons respond to that very nicely.
Just try sometime...take your common 185 R 14 vanagon tire..most
commonly available in D load rating ..
if you can find them, run C load rating ones in the front and D's in the
rear..
and TUNE the tire pressures to about 4 to 6 more psi in the rear, and
not too high in general..
like aim for the best combination of ride and steering response (
turn-in ) and cornering stability.
for 14's ..which I find can never really be that good on Vanagons ..
this set up is not bad.
here's what handles like a dream on my good rig..
front tires are Michelin Agilles 205/65 R 15 LT's ( equal to C loat
rating )
rears are 215/65 in a speed rating I really don't like due to harshness
..H speed rating ...
but on the rear their fine.
That rear tire is actually a Sports Sedan tire rather than a Light
Truck Tire ..and is up to the job I'm sure.
That rig tracks as straight as could be and doesn't over or understeer
at all.
as I've suggested before ..
drive other vanagons besides yours whenever you can.
You may find that yours actually behaves fairly well handling and ride
wise..
or you may find yours sucks and this arrangement on this other van is
much better.
heck ..car magazines sometimes track test cars with dozens of different
tire/wheel combo's.
and experiment with tire pressures. In racing tire pressures are
adjusted in increments as fine as 1/10th of a psi .
"Measured Cold" is the normal standard.
fwiw ..I have started out many Vanagon trips with a huge load and
started with 48 psi rear tire pressures..
and hour or two later ...I'm like ...just doesn't feel right. I let out
about 6 pis ( hot ) ..ahhhh ! ..so much better !
lastly my favorite 'near crash emergency traction story.;
( speaking btw as someone who has raced cars and motorcycles since the
60's and has way more than a million miles driving experience who just
loves driving in snow, ice, gravel etc. )
I'm descending Mt. Ashland in So. Oregon after a day of skiing, on
summer tires in a RWD turbo volvo sedan ( Inga ) on mixed pavement and
old compacted snow . > old snow is the worst btw...fresh dry snow is
wonderful ..
old wet snow is just awful > .
I come around a downhill bend a bit too fast.....and I realize I
might loose it and I can just see myself in the inside ditch in a few
seconds.
I let off all gas and brakes and drop it down one gear on the auto
trans and counter steer lightly ...
expecting that adding some 'whoa ' to the rear tires will pull the car
straight some ..and it does by golly - - Very nicely ...and for a
second or two I was not in complete control of my destiny at all, but
that action was exactly right thing to do.
briefly ..another time, same road and conditions I'm sort of 'racing' a
young guy in an FWD Sirocco ...I'm right behind him just pacing him
...he goes around a bend ...and we're mildly performance driving
.....we're both on summer tires .. right in front of me he spins around
and ends up in the inside ditch facing backwards from the direction he
was going ..pretty normal actually.
lol...anyway ..it's all good.
Drive safely. There are huge areas of improvement in
ride/handling/safety available through wheel size, tire size and type,
and tire pressures.
On 7/11/2015 6:12 AM, Dan N wrote:
> thank you Dennis for the link...
>
> I have a 4WD SUV that need rear tires... the link came in at the right
> time...
>
> the question at rotation time... the 1/2 worn tires will go to the rear at
> rotation...
>
