What exactly does cold pressure mean?

On 12/01/2010 05:51 PM, charter wrote:
>> If the door decal specifies 80psi and the tire sidewall max
>> is 80psi, I would suspect someone has installed a reduced
>> load range tire on the van.
>> Lugnut
>
> Not necessarily; it's perfectly acceptable to have the sticker
> pressure the same as max tire pressure. And this is often the case
> when a tire is required to carry near its max capacity.
>
> Having a "max" pressure of 80 psi does not mean the tire will blow at
> 81 psi, or sustain damage. In fact, most tires do not blow till
> atleast 2 - 3 times over its max pressure, sometimes up to 5 on
> commercial H+ rated tires (500+ psi). For LT tires, 80 psi, or load E
> rating, is the max you can go. Unless you want to convert your van to
> 19.5" wheels and run commercial tires.
>
>
> As both an engineer and commerical driver, I would say a MAJORITY of
> 15 passenger van rollovers are the operator's fault. Most people don't
> think twice when piloting a van carrying 3000 lbs of human cargo; they
> accelerate, stop, and swerve the same as they would in their Accord.
> Of course that's asking for trouble! Consider this: there're millions
> of big rigs and commercial busses runing 100,000s miles a year out
> there, and every singe one of them has a MUCH higher CG than even a
> fully loaded van (think tanker, or meat truck). Should we ban all of
> them because they're prone to roll overs?
>
> Your typical tour coach has 10,000 lbs of people riding 6 feet off the
> ground, with a vehicle width of only 1.5 times wider than a van. What
> do you think would happen if the coach driver swerves or performs a
> "fish hook manuver" at 75 mph? Truth is, bus drivers rarely have to do
> that. If 15 passenger van drivers learn to 1) not drive so fast, and
> 2) not follow so closely, then him or her wouldn't have to either.
>
> The other thing is maintenance. Safety studies discovered 57% of 15
> passenger van crashes had one or more tires severely under-inflated.
> Is that a design flaw or driver neglegance. Since 15 pass van tires
> are already near their max weight capacity, any underinflation is
> fatal. I can gurantee that if every 15p van has its tires at 60 psi
> fron / 80 psi rear, blowouts will be close to none.
>
> The sad reality is, your typical church driver or sports coach know
> nothing about the above, and that's why we hear these tragic stories
> of multiple children injured or killed in 15 pass van crashes. I'm
> not saying the design of these vans are perfect, or even good, but
> they're far from the death traps that media has led us into believing.

no dude, they're very much death traps. while you're right that drivers
have a large responsibility, the drive dynamics of these things is
abysmal. no vehicle should roll just because of a blowout, and these
things do. and it's not like the market into which they're being sold
is populated by experienced professional drivers. if the manufacturers
/know/ they're being sold to amateurs, and they do, they need to be
designed [and regulated] accordingly, just like with suv's.

one more thing - comparing 15p handling to a passenger coach is a flawed
analogy - the coach handles /much/ better and has /far/ superior suspension.

--
nomina rutrum rutrum

On Dec 1, 9:34*pm, jim beam > wrote:

> no dude, they're very much death traps. *while you're right that drivers
> have a large responsibility, the drive dynamics of these things is
> abysmal. *> one more thing - comparing 15p handling to a passenger coach is a flawed
> analogy - the coach handles /much/ better and has /far/ superior suspension.
>
> --
> nomina rutrum rutrum- Hide quoted text -
________________
Anyone here drive a Ford Transit or Dodge Sprinter? Just wondering
how these new "Euro-merican" converts handle compared to what they
replaced.

And you're right jim about the handling of Econolines and Expresses
and the old B-250s. Why must a light truck handle like, well, a
TRUCK? How difficult is it for GM or Ford to center up the steering
better and give the things *some* feedback? I'm sure vehicles with
taller suspensions probably have a different way to achieve this, so
why isn't it being done?

> - Show quoted text -

-CC

> no dude, they're very much death traps. *

Everything is relative. Ever been in a 135,000 lbs 7 axle tanker
through the BC rockies?

> while you're right that drivers
> have a large responsibility, the drive dynamics of these things is
> abysmal.

Abysmal compared to what? The aforementioned Accord? Or other vehicles
with similar carrying capacity?

> no vehicle should roll just because of a blowout, and these
> things do.

Ever seen a steer tire blowout on a rig? Let's just say the truck does
not simply jacknife, and slide to a controlled strop...

> *and it's not like the market into which they're being sold
> is populated by experienced professional drivers. *if the manufacturers
> /know/ they're being sold to amateurs, and they do, they need to be
> designed [and regulated] accordingly, just like with suv's.

So, the problem is still the operator, to a large degree. Let's look
at a vehicle that IS certified as a bus, and that IS considered safe
to carry 19 children around in:
http://www.brightbill.com/bluebird_micro.htm

Do you think this will be any less likely to roll than a 15 pass van?
Weighing even more, yet still using 245/75/16 tires, do you think the
tires will be any less likely to blow if underinflated? The difference
here, is that the minibus will be operated by commercial drivers, with
mandated pre-trip checkups.

638hp Corvettes are also designed and sold to "amateurs". Should GM be
held liable if I floor the car in a twisty canyon, spin out, and go
off a cliff? After all, an amature vehicle should be fool-proof right?

When you have 15 human lives on board, you are no longer an amateur,
regardless of your profession. You are required, by ethics, to ensure
that basic safety is met on the vehicle - proper tire sizes (load
range E), psi (80), use of seat belts, etc.

> one more thing - comparing 15p handling to a passenger coach is a flawed
> analogy - the coach handles /much/ better and has /far/ superior suspension.

I can only assume you've never driven a coach. The only thing better
about their suspension is they're cloud soft, puts some Mercedes to
shame. But because of that, they're some of the laziest handling, most
irresponsive, least road feel, systems ever designed. A school bus
feels like a sportscar by comparison, and that's saying a lot...

Again, I'm not saying the vans are perfect; far from it. Here's what I
would change:

- requirement for lengthend wheelbase like all GM vans
- or, use of dual rear wheels
- high roof strength

But none of that would help if the driver is negligent. Put two
passenger tires, at 35 psi, on the rear duals, drive 80 mph on a 100
degree Arizona highway, and what happens? Blowout and rollover just
like a single wheel van.

Yes, the vans could use some improvement. But add some media hype,
making the victims and their drivers look like innocent angels, while
OEMs like evil monsters, and what do you get? Widespread rumour that
you'll die if ever put one step into a 15 passenger van.

A nephew of mine, he drove an 18 wheeler for a while.Now he drives a
tour bus/coach for Roberts company, Nashville.I reckon he knows
something about tires and tire pressure.
cuhulin

On Dec 2, 11:48*am, wrote:
> A nephew of mine, he drove an 18 wheeler for a while.Now he drives a
> tour bus/coach for Roberts company, Nashville.I reckon he knows
> something about tires and tire pressure.
> cuhulin

I get the impression that some posters are ignoring the fact that 15-
passenger vans only have one rear tire on each side. Comparing these
to vehicles with 2 or more rear tires on each side does not make
sense.

This is an important factor in the rollover risk. About 15% of fatal
rollovers in 15-passenger vans were initiated by a rear tire blowouts
or tread separation.

Fatal left-rear tire failures are more common. 15-passenger vans have
an aisle on the right side and the left tire ends up carrying most of
the weight. Some transit operations have switched to center ailse
seat layouts.

Back in 1992 when I visited Mexico for five days, a woman out in the
country not far from Reynosa, she thought my 1978 Dodge van was a
Mexican bus.She flagged me down.I took her to Reynosa.
They use a lot of vans in Mexico for city buses/transit.
cuhulin

On Dec 1, 8:51*pm, charter > wrote:
> > If the door decal specifies 80psi and the tire sidewall max
> > is 80psi, I would suspect someone has installed a reduced
> > load range tire on the van.
> > Lugnut
>
> Not necessarily; it's perfectly acceptable to have the sticker
> pressure the same as max tire pressure. And this is often the case
> when a tire is required to carry near its max capacity.
>
> Having a "max" pressure of 80 psi does not mean the tire will blow at
> 81 psi, or sustain damage. In fact, most tires do not blow till
> atleast 2 - 3 times over its max pressure, sometimes up to 5 on
> commercial H+ rated tires (500+ psi). For LT tires, 80 psi, or load E
> rating, is the max you can go. Unless you want to convert your van to
> 19.5" wheels and run commercial tires.
>
> As both an engineer and commerical driver, I would say a MAJORITY of
> 15 passenger van rollovers are the operator's fault. Most people don't
> think twice when piloting a van carrying 3000 lbs of human cargo; they
> accelerate, stop, and swerve the same as they would in their Accord.
> Of course that's asking for trouble! Consider this: there're millions
> of big rigs and commercial busses runing 100,000s miles a year out
> there, and every singe one of them has a MUCH higher CG than even a
> fully loaded van (think tanker, or meat truck). Should we ban all of
> them because they're prone to roll overs?
>
> Your typical tour coach has 10,000 lbs of people riding 6 feet off the
> ground, with a vehicle width of only 1.5 times wider than a van. What
> do you think would happen if the coach driver swerves or performs a
> "fish hook manuver" at 75 mph? Truth is, bus drivers rarely have to do
> that. If 15 passenger van drivers learn to 1) not drive so fast, and
> 2) not follow so closely, then him or her wouldn't have to either.
>
> The other thing is maintenance. Safety studies discovered 57% of 15
> passenger van crashes had one or more tires severely under-inflated.
> Is that a design flaw or driver neglegance. Since 15 pass van tires
> are already near their max weight capacity, any underinflation is
> fatal. I can gurantee that if every 15p van has its tires at 60 psi
> fron / 80 psi rear, blowouts will be close to none.

This is why a broken tire belt on our van got my attention. We have
never let the tire pressure get low and the tires had plenty of life
left. We did not hit any potholes at high speeds. Fortunately, we
felt
the broken belt in the steering wheel and got the tires replaced.

"Tom Adams" > wrote in message
...
On Dec 2, 11:48 am, wrote:
> A nephew of mine, he drove an 18 wheeler for a while.Now he drives a
> tour bus/coach for Roberts company, Nashville.I reckon he knows
> something about tires and tire pressure.
> cuhulin

I get the impression that some posters are ignoring the fact that 15-
passenger vans only have one rear tire on each side.
*****

I never had nor drove one of these. I DID have a Dodge 2500 Custom
Van, 1997 model. This was scary as hell when I first bought it. It was
unwieldy in the wind, it rocked and rolled, unstable on braking, etc.

I first bought the best set of Michelin tires I could afford. That helped a
lot. This definitely helped.

Next, I replaced the original shocks with Bilstein shocks. That helped
a bunch.

And last, I installed an aftermarket roll bar assembly at the rear of the
van. This greatly improved the wind problems on the road.

This transformed the wickedest driving bitch of a van into something
that was relatively comfortable and controllable.

Although I am not a Dodge person, this was the most dependable
vehicle of its type I have ever owned. In the years I had it, it used
up an evaporator core and a water pump, and was pleasant to drive.

On Dec 2, 10:03*am, Tom Adams > wrote:
> On Dec 2, 11:48*am, wrote:
>
> > A nephew of mine, he drove an 18 wheeler for a while.Now he drives a
> > tour bus/coach for Roberts company, Nashville.I reckon he knows
> > something about tires and tire pressure.
> > cuhulin
>
> I get the impression that some posters are ignoring the fact that 15-
> passenger vans only have one rear tire on each side. *Comparing these
> to vehicles with 2 or more rear tires on each side does not make
> sense.
>
> This is an important factor in the rollover risk. * About 15% of fatal
> rollovers in 15-passenger vans were initiated by a rear tire blowouts
> or tread separation.
>
> Fatal left-rear tire failures are more common. *15-passenger vans have
> an aisle on the right side and the left tire ends up carrying most of
> the weight. *Some transit operations have switched to center ailse
> seat layouts.

Well, I did post a link for the Bluebird Microbird, which comes in a
lot of single wheel setups, as do many shuttle busses. These busses
have even higher CG than a 15pass van, yet, most parents won't think
twice about putting 19 of their kids in one, because it is a "school
bus".

I do agree with you that the left weight bias is a safty risk. There
is no real easy fix, other than putting the middle 3 rows on a sliding
track, and have them slide towards the center.

Regarding tires, if they're within the load limit, and are pumped to
80 psi, then they should not fail. Any failure is a defect from the
tire manufacturer, and lawsuit waiting to happen.

BTW, I don't believe this 45% weight resting on left rear tire hype.
Assume it's true, then: left rear should be around 40% by simple
geometry, that leaves the front tires carrying 10% and 5% of the van's
weight? Impossible, you'd catch air over a speed bump if that was the
case.

The rear tires carrying 35% / 30%, with front tires 15% and 20%, is a
more plausible case. Even that seems exaggerated.

On Dec 3, 1:21*am, charter > wrote:
> On Dec 2, 10:03*am, Tom Adams > wrote:
>
>
>
>
>
> > On Dec 2, 11:48*am, wrote:
>
> > > A nephew of mine, he drove an 18 wheeler for a while.Now he drives a
> > > tour bus/coach for Roberts company, Nashville.I reckon he knows
> > > something about tires and tire pressure.
> > > cuhulin
>
> > I get the impression that some posters are ignoring the fact that 15-
> > passenger vans only have one rear tire on each side. *Comparing these
> > to vehicles with 2 or more rear tires on each side does not make
> > sense.
>
> > This is an important factor in the rollover risk. * About 15% of fatal
> > rollovers in 15-passenger vans were initiated by a rear tire blowouts
> > or tread separation.
>
> > Fatal left-rear tire failures are more common. *15-passenger vans have
> > an aisle on the right side and the left tire ends up carrying most of
> > the weight. *Some transit operations have switched to center ailse
> > seat layouts.
>
> Well, I did post a link for the Bluebird Microbird, which comes in a
> lot of single wheel setups, as do many shuttle busses. These busses
> have even higher CG than a 15pass van, yet, most parents won't think
> twice about putting 19 of their kids in one, because it is a "school
> bus".
>
> I do agree with you that the left weight bias is a safty risk. There
> is no real easy fix, other than putting the middle 3 rows on a sliding
> track, and have them slide towards the center.
>
> Regarding tires, if they're within the load limit, and are pumped to
> 80 psi, then they should not fail. Any failure is a defect from the
> tire manufacturer, and lawsuit waiting to happen.
>
> BTW, I don't believe this 45% weight resting on left rear tire hype.
> Assume it's true, then: left rear should be around 40% by simple
> geometry, that leaves the front tires carrying 10% and 5% of the van's
> weight? Impossible, you'd catch air over a speed bump if that was the
> case.
>
> The rear tires carrying 35% / 30%, with front tires 15% and 20%, is a
> more plausible case. Even that seems exaggerated.- Hide quoted text -
>
> - Show quoted text -

I don't know where you got 45%. I should have said "more of the
weight"
rather than "most of the weight".

Here is a center aisle layout for a 15 passenger van (second layout):

http://www.vpsiinc.com/home/submenu....SMID=26&OID=27

BTW, VSPI Inc. is the best organization I know of when it comes to
managing these vans, and there is lots of info on their policies on
the web. About the only way to improve on VSPI's approach is to
reduce the seating capacity. I don't think they require daylight
running
lights, that's the only criticism I have of them.