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Re: [VB] tire pressures
----- Original Message -----
> Jamie,
> That looks like a good test to me. The pressure change would be caused by
an increase in the temperature of the air in the tire. If the tire is
under-inflated the tire will get hotter than it should. If the temperature
goes up enough to cause the pressure to increase more than 3 psi, the
pressure is too low.
> Dave
>
> > This seems to be a very good rule.
> > a good guide (from a tire company engineer) is to compare cold pressure
> > with the pressure after at speed for 15 minutes.If the pressure goes up
3psi
> > you are just right; more than 3psi your starting pressure was too low,
and
> > less than 3psi your starting pressure was too high.
I took my camper for a drive today.. checked the tire pressure at 40 psi
all around.
I drove for about 15 min.. and checked the pressure and they had all
increased about 3psi
so.. I am thinking I might have the pressure almost correct.
Andy alerted me to a point I was missing,, and that is VW talks about
pressure rear vz front.. at about 3 / 4 ratio... based on weight ratio that
is about the same..
My camper has almost equal weight for front and rear axles.. that is why
I decided on 40 psi on front and rear..
tires say.. 1700 lbs at 65 psi
they have about 1100 lbs on them.. so.. 1100 / 1700 X 65 = 42 ... I
lowered that a bit. to round it to 40psi
If I fully load this vehicle , I will have to increase the tire pressure to
about 53... I'll probably just go with 40 light load.. and 50 loaded...
I will try to do some infared and psi checks in the next little while..
tires still look now, no uneven wear..
Jamie
----- Original Message -----
From: "Robt Mann" <robtm@xxxxxxxxxx>
To: "VW type 2 late aircooled" <type2@xxxxxxxxx>
Sent: Saturday, August 16, 2008 3:33 PM
Subject: Re: [T2] tire pressures
> Jamie wrote:
>
> >Here is a comment about tire pressure I have never heard before..
> >because we don't all run factory origninal tires with the same specs..
the
> >tire pressure listed on the door panel or the sidewall of the tire can
not
> >always be trusted..
> >
> >This seems to be a very good rule.
> > a good guide (from a tire company engineer) is to compare cold pressure
> >with the pressure after at speed for 15 minutes.If the pressure goes up
3psi
> >you are just right; more than 3psi your starting pressure was too low,
and
> >less than 3psi your starting pressure was too high.
>
> That is a pretty crude rule-of-thumb. The P rise depends on
> the ambient T, and on how bumpy the test road is - the bumpier, the
> more flexing of the sidewalls and pulsing of the P which causes the P
> rise.
>
> --
> Robt Mann
> Whangaparaoa, New Zealand
Date: Sat, 28 May 2005 20:00:20 -0400
Subject: Re: [T2] Vehicle Weight and Tires
Andy
When I calculated this first,,, I took into consideration Vw originally
installed tires with max weight at 40 psi ... and they recommended 40 psi
on
the rear,, and 30 on the front for fully laden vehicle
That is 100 percent inflation on the rear,, and 75 percent inflation on the
front...
then I used the same method to calc as you did.. but I threw in that 75
percent
factor for the front
Also.. i rounded the 47.8 psi up to 48 psi for the rear...
the front came in at 40 psi with the 75 percent factor
Looks like we agree on the rear at about 47 - 48 psi... but I still wonder
about
that 75percent ratio front to rear,,,,
You asked 2 questions.. Why do you have so much weight in the front? Or are
the
numbers reversed?
and you were interested in the year,, as I said in the original message ,,
my
camper is a 74 deluxe
The numbers are NOT reversed... I looked at them the same way...they do
looked
reversed..
I should have included my conclusion on that in the original email..
When I first weighed the van,, it was 2182 lbs on the front,, and 2380 for
the
rear... 200 lbs heavier in the rear
this is loaded with my camping gear, gas and the driver...
then I weighed it as I headed down the road... with one more passenger in
the
front,, and 2 in the rear.
the front passenger weighs in at 200 lbs,, and the 2 in the back add up to
200
lbs total...[2 kids that weigh 100 lbs each...]
These numbers are guesses,, as I didn't weigh all the people,, they were in
the
camper when it was on the scale.. and the front got heavier than the rear...
Yes,, it appears as GVW is about 5268 lbs....
Jamie wrote
I had the chance to weigh my camper recently, so here is some info...
My 74 Westfalia Camper ....
Loaded, with the driver , and 1 passenger in the front, about 400 lbs right
there !
2 passengers in the rear... only about 200 lbs for both of them!
Scale Weight on Front: 2788 lbs......1399 lbs on each tire
Scale Weight on Back : 2480 lbs......1240 lbs on each tire
Total weight 5268 lbs
Tires:
Yokohama LT195/75R14 Load range "D" M&S
1710 lbs max _at_ 65 psi
So,, if I did the math right,, I should put 48 psi in the rear tires.. and
40 in
the front tires when I have this much load in the camper....
Jamie Rivers
----- Original Message -----
Sent: Saturday, May 28, 2005 6:57 PM
Subject: Re: [T2] Vehicle Weight and Tires
> Without published data from the tire manufacture, you can get close with
> this:
>
> actual (or max. expected) gross tire weight (or half the axle weight) /
> max. tire weight rating * tire max. inflation
>
> In this case:
>
> front 1399 / 1710 * 65 = 53
> rear 1240 / 1710 * 65 = 47
>
>
> Two questions:
>
> What year is your van, Jamie? A quick glance at my '79 owner's manual
> shows a GVWR between 4960 (station wagon) and 5070 (kombi and delivery
> van). Looks like you may be outside that.
>
> Why do you have so much weight in the front? Or are the numbers reversed?
>
>
> Andy McKinley
> airhedz_at_earthlink_dot_net
> >From: "Jamie"
> >
> >
> >I had the chance to weigh my camper recently, so here is some info...
> >
> >
> <snip>
>
> >Scale Weight on Front: 2788 lbs......1399 lbs on each tire Scale Weight
on
> >Back : 2480 lbs......1240 lbs on each tire Total weight 5268 lbs
> >
> >Tires:
> >
> >Yokohama LT195/75R14 Load range "D" M&S
> >
> >1710 lbs max _at_ 65 psi
> >
> >
> >
> >So,, if I did the math right,, I should put 48 psi in the rear tires..
and
> >40 in the front tires when I have this much load in the camper....
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