VW tre pressure recommendation very different for 2005 models?

A

av_audi

· Registered

Joined Apr 5, 2001

·

6,814 Posts

Discussion starter · #21 · Feb 7, 2005

Only show this user

Re: VW tre pressure recommendation very different for 2005 models? (E36BMW)

Quote, originally posted by E36BMW »

Our 05 was delivered with 35 in the fronts and 40 in the rear. My VW NA connection says VW wants the cars handling to err on the understeer side of the equation thus the higher rear pressures.

I really don't think it has anything to do with that. The full load requirement seems to be driving these new pressure recommendations. Extremely high rear tire pressure may in fact increase the tendency to "swing out the tail."

 

A

av_audi

· Registered

Joined Apr 5, 2001

·

6,814 Posts

Discussion starter · #22 · Feb 7, 2005

Only show this user

Re: VW tre pressure recommendation very different for 2005 models? (annapoal)

Quote, originally posted by annapoal »

For those who want a passat tire pressure sticker with the old style pressures for loads and speeds, the part # is 3B0-010-275-A.

 

E36BMW

· Registered

Joined Nov 11, 1999

·

3,490 Posts

#23 · Feb 7, 2005

Only show this user

Re: VW tre pressure recommendation very different for 2005 models? (av_audi)

Quote, originally posted by av_audi »

I really don't think it has anything to do with that.... Extremely high rear tire pressure may in fact increase the tendency to "swing out the tail."

Higher pressures (within reason) equals higher grip.
http://www.tirerack.com/tires/...s.jsp


Modified by E36BMW at 11:41 AM 2-7-2005

 

T

tjl

· Registered

Joined Mar 24, 2001

·

28,732 Posts

#24 · Feb 7, 2005

Only show this user

Re: VW tre pressure recommendation very different for 2005 models? (av_audi)

Quote »

increased chance of damage when tires hit hard object.

Wouldn't higher tire air pressure reduce the chance of damage to the wheel when hitting a pothole or whatever, due to lower chance of bottoming out the tire?

 

E36BMW

· Registered

Joined Nov 11, 1999

·

3,490 Posts

#25 · Feb 7, 2005

Only show this user

Re: VW tre pressure recommendation very different for 2005 models? (tjl)

Quote, originally posted by tjl »

Wouldn't higher tire air pressure reduce the chance of damage to the wheel when hitting a pothole or whatever...

Correct.

 

A

av_audi

· Registered

Joined Apr 5, 2001

·

6,814 Posts

Discussion starter · #26 · Feb 7, 2005

Only show this user

Re: VW tre pressure recommendation very different for 2005 models? (E36BMW)

Quote, originally posted by E36BMW »

Higher pressures (within reason) equals higher grip.

I don't disagree with that at all. It's the within reason part I am wondering about. I really wonder whether 45-50psi in the rear is reasonable when VW recommended 28psi for half loads before this new ridiculous policy. I have a feeling 50psi in the rear would make the rear axle act like one of those empty tow trailers that bounce around all over the road.


Modified by av_audi at 12:48 PM 2-7-2005

 

A

av_audi

· Registered

Joined Apr 5, 2001

·

6,814 Posts

Discussion starter · #27 · Feb 7, 2005

Only show this user

Re: VW tre pressure recommendation very different for 2005 models? (tjl)

Quote, originally posted by tjl »

Wouldn't higher tire air pressure reduce the chance of damage to the wheel when hitting a pothole or whatever, due to lower chance of bottoming out the tire?

Unless you are talking about really underinflated tires, the answer is no. See for example http://forums.vwvortex.com/zer...15395.
Think of it this way. Poke a moderately inflated balloon with a pen, and it will deform to accomodate the pen. Now do the same thing on a higly inflated balloon, and chances are it will just pop. If the pressure is way too low, the pen will reach all the way to the other side of the balloon, press against the carpet, and puncture it.
An overinflated tire does not have enough "give" to absorb strong hits, while an underinflated one will get shredded against the rim.
Moral of the story, there is a good reason why VW went through all the trouble of listing vastly different pressures (especially for the rears) for various loads an speeds, until we fell again victim to negligent people.



Modified by av_audi at 4:03 PM 2-7-2005

 

L

larrs

· Registered

Joined Apr 26, 2003

·

117 Posts

#28 · Feb 7, 2005

Only show this user

Re: VW tre pressure recommendation very different for 2005 models? (John_E)

Quote, originally posted by John_E »

from the AAA: http://www.csaa.com/global/art....html "... Overinflation shortens tire life and can make vehicle handling seem "light" or "skittish," particularly on wet roads."

I didn't think we were talking about overinflation. What was said was that some folks lower the tire pressure for driving in the wet. I assumed (perhaps incorrectly) that they are lowering from correct pressure, and I didn't understand why that would help in the wet.

 

L

larrs

· Registered

Joined Apr 26, 2003

·

117 Posts

#29 · Feb 7, 2005

Only show this user

Re: VW tre pressure recommendation very different for 2005 models? (av_audi)

Quote, originally posted by av_audi »

I think there are two things going on here. Too high of a pressure reduces wet traction, that just plain grip on wet surfaces. However, increased tire pressure reduces the contact patch size , which reduces the amount of water that needs to be evacuated, which in turn reduces the tendency to hydroplane. So as always, you need to strike a good balance between these two competing tendencies.

Sorry if I wasn't clear. What I meant to say was that I think a properly inflated tire is better in the wet than an underinflated tire. I didn't understand why someone would lower pressures for driving in the rain.

 

V

VWGUY4EVER

· Registered

Joined Nov 17, 2000

·

3,386 Posts

#30 · Feb 8, 2005

Only show this user

Re: VW tre pressure recommendation very different for 2005 models? (larrs)

For a heavy weight like the W8, 39/36 is fine. For a lighter V6 or 1.8T, 36/32 is fine. Thi from a guy in the tire business for 20 years. 45psi on the rear of a lightly loaded 1.8T will be horrible. Besides, read the side of your tires. Most broad market tires have a max inflation of 44 psi recommended by the tire manufacturer. The whole time Ford was recommending 28 & 29psi for Explorers & Expeditions, I had my guys setting them at 35 psi

 

A

av_audi

· Registered

Joined Apr 5, 2001

·

6,814 Posts

Discussion starter · #31 · Feb 8, 2005

Only show this user

Re: VW tre pressure recommendation very different for 2005 models? (VWGUY4EVER)

Quote, originally posted by VWGUY4EVER »

45psi on the rear of a lightly loaded 1.8T will be horrible. Besides, read the side of your tires. Most broad market tires have a max inflation of 44 psi recommended by the tire manufacturer.

My OEM MXV4+'s had 44psi max, my new ones have 54psi max. There must have been a changes along the way (overall, for the better).
Today, I ended up taking a roundabout way to work to avoid a freeway jam caused by an overturned dump truck, taking a freeway which allows comfortable cruising at 85-90mph. With a mere 32/31psi on my light 1.8T 5-speed, I was feeling every ripple of the concrete road surface. The car was planted solid as if on rails, but most people would have described that ride as harsh. I can only imagine how horrible the ride would be with pressures close to 40psi.
As a side note, many manufacturers recommend the same pressure for half and full loads that are far lower than VW's Wife's Camry has a 30psi all around recommendation, including for full load. Tires are 195/70 14. By doing the right thing and recommending high pressures for full loads for maximum safety, VW is getting penalized by being forced to dial a really harsh ride into their vehicles.