Date: Mon, 1 Aug 2005 06:54:05 -0700
Reply-To: Larry Chase <roadguy@ROADHAUS.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Larry Chase <roadguy@ROADHAUS.COM>
Subject: Re: Tire pressure question 2
In-Reply-To: <20050801041327.9438FD80B3@mx03.csee.siteprotect.com>
Content-Type: text/plain; charset="US-ASCII"
Volks,
I truly do not mean any disrespect to Jim or Otmar, both of whom I admire a
great deal.
But I have to disagree with the advice given.
- The door sticker is a very valuable piece of info.
- Over inflating tires is dangerous
If you are running tires that are the same size as OE and have the same
specs as OE .... Then following the door sticker (Silver Sticker) info.
Vehicle manf's do a lot of testing to determine these requirments.
If you are using tires that are of a different size or load spec than the OE
tires ... That's were it gets tricky.
Jim referred to the "Load Tables" he's right ... They are a very useful tool
and I have them.
They are available thru the Tire & Rim Association for US standards and
their European counterpart "ETRTO" for
European standards.
To calculate proper tire pressure for a non stock tire you need four things:
1) VW Silver Sticker (door jam) tire info
2) Tire Load Inflation Tables (Weight a specific load range tire carries at
various psi values)
3) Max Load Capacity & Max Inflation Pressure of the OE Tires (this tells us
VW's Safety Reserve)
4) Max Load Capacity & Max Inflation Pressure for the current tire.
Your starting point is the VW Silver Sticker (on door jam) from which you
determine the manufacturer's target tire load capacity with safety reserve.
By looking up the specified load capacity of the OE tire combinations in the
load inflation tables, you then match the new tire inflation to that value.
Doing this identifies the safety reserve VW used.
Fortunately I have been able to acquire the "Load Inflation Tables" and
because of the various tire info surveys folks responded to (Silver Sticker,
GVWR & OE Tire)I now have the data needed for all Vanagon years.
Bottom Line ....
I would be happy to calculate a "Recommended Inflation Pressure Range" for
any tire.
IMHO ... The best part of this methodology is that it make sense.
Larry Chase
www.roadhaus.com
www.roadhaus.com/shops.html
www.roadhaus.com/tires.html
- - -
From: jimt <camper@TACTICAL-BUS.INFO>
Subject: Re: Tire pressure question 2
Many mfr post load tables for their load rated tires. However I just
finished about three days of digging on the web for the most common tires we
use and found no tables. All the tables start just above our vehicles and
do not really relate to us at all.
However by using those tables, notes contained in them and then noting the
relationships on them I came up with this.
If running a base vanagon use the card. If you are running a camper the
card is still good but would recommend 3psi increase front and rear. If
your van is like mine and routinely weighs in at 4600 then add 5psi to the
front and rear. These numbers that I am using are based on normal drive
with about 300 lbs of extra load for cargo being added from time to time.
Note also that these numbers are assuming that the weight increase will be
to the middle of the vehicle and not over one axle or the other.
With my van I did the add of 5 psi about three months ago after noting
strange tire wear on the front that suggested under inflation as well as
some strange handling. The handling corrected and the wear pattern has
halted. Nice to see that I now have some support for the number I guessed
at. The guesstimate part was done by first inflating to 3 psi greater and
looking at the contact patch area and sidewall bulge on one front tire. I
then added 2psi more and the tire shape looked much better and I then
matched the pressure on the other three tires and checked appearance and
then test drove on the highway.
With any changes in tire pressure look for changes in wear patterns on the
front tires. This is where it will show most and soonest.
Jimt
- - -
Date: Sun, 31 Jul 2005 11:24:00 -0700
From: Otmar <otlists@EVCL.COM>
Subject: Re: Tire pressure question 2
Has anyone Ever seen a radial tire on a Vanagon with signs of over
inflation? I certainly never have. Maybe I take the corners too fast. :)
I always run my cars at max sidewall pressure rating or a little over. 55
PSI all around with my Agelis 205-65 15s on the Stretch. I also usually run
pretty heavy van (5800 to 6300 lbs trip weight) and like the increased fuel
economy that high tire pressure brings. In my electric and hybrid cars I run
10 psi over the sidewall rating. They roll really well.
In exchange the ride is a bit harsher than it would be with lower pressure.
Overall as I see it, high tire pressure reduces heat buildup and therefore
reduces tire failures but does make for a somewhat louder and harsher ride.
It can also reduce traction but seems to make the van more stable. With
those thoughts in mind, tire pressure becomes a personal preference. I don't
think I've ever even read the recommendations on the door sticker. :)
