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Recommended psi is 37. Why?

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jax2006

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Discussion starter · #1 ·
As posted previously in this forum, the recommended psi for tires on the new passat is 37. This looks like a trend as other new vehicles like the acura tl also recommends 37 psi. I'm so use to 33 being the usual psi level.
Anyone know why it's different now?
 
#3 ·
Re: Recommended psi is 37. Why? (PCpassat06)

The manufacturer's recommended pressure will always be lower than the max cold pressure shown on the tire. For what it's worth, I usually split the difference. A pressure above the recommended pressure will improve your gas mileage and help with tire wear, but will decrease ride comfort.
 
#4 ·
Re: Recommended psi is 37. Why? (PCpassat06)

Quote, originally posted by PCpassat06 »
It may differ from what you read on the tire.

Tires never have recommended pressures marked on them, as they don't know how they will be used (front, back, 2400 pound car, 5000 pound car, etc). Tires only will have the maximum safe pressure that will not cause internal damage.
 
#5 ·
Re: Recommended psi is 37. Why? (jax2006)

Quote, originally posted by jax2006 »
This looks like a trend as other new vehicles like the acura tl also recommends 37 psi. Anyone know why it's different now?

Higher pressures allow higher fuel mileages. However, this would be at the expense of some comfort.
 
#6 ·
Also, a decrease in traction if too high. I plan to set my fronts to about 34PSI and rears to 37PSI.. something like that.
JT
 
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#7 ·
Re: (x9t)

Quote, originally posted by x9t »
Also, a decrease in traction if too high.

True, but too high is in a range that's beyond the tires max pressure---usually above 50psi before traction suffers.
Higher pressures causing a decrease in traction is a common misunderstanding of high tire pressures. On a road coarse, it is very common to use tires pressures close to 45psi for increased traction when cornering. The higher pressure prevents sidewall rollover which keeps an even tire footprint on the asphalt. Lower tire pressures are more applicable to drag racing.
Back to the topic; The 37psi recommendation is for safety. As I mentioned, the higher pressure enhances the cars' handling ability especially in high-speed maneuvers.
BTW: I've always run 35-37psi in all tires on all our cars. 35psi is also the general recommended tire pressure by TireRack.com


Modified by E36BMW at 5:28 AM 11-15-2006
 
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#8 ·
Re: Recommended psi is 37. Why? (jax2006)

I was having problems with my Tire Preasure monitoring system and had taken it in 5 times. Everything the dealer did was as directed from VW. The 5th. time a VW tech came to work on it and was unable to correct the problem. I am told they then contacted VW in Germany and was advised the tires needed 40 psi. Needed to reset the whole system and has now been about a week and have not had the light come back on. Tires had been at 35 psi. Do feel a bit of a difference in the ride.
 
#9 ·
Re: (E36BMW)

Quote, originally posted by E36BMW »
True, but too high is in a range that's beyond the tires max pressure---usually above 50psi before traction suffers.
Higher pressures causing a decrease in traction is a common misunderstanding of high tire pressures. On a road coarse, it is very common to use tires pressures close to 45psi for increased traction when cornering. The higher pressure prevents sidewall rollover which keeps an even tire footprint on the asphalt. Lower tire pressures are more applicable to drag racing.
Back to the topic; The 37psi recommendation is for safety. As I mentioned, the higher pressure enhances the cars' handling ability especially in high-speed maneuvers.
BTW: I've always run 35-37psi in all tires on all our cars. 35psi is also the general recommended tire pressure by TireRack.com

Very well said. The only time this would not be true would be tire sizes 315 and bigger are with specialty tires such as Drag Radials or Drag slicks. I keep the pressure around the 36psi range. Seems to strike a good balance between ride comfort and handling (The michelins that came on the car tend to get really mushy at 33psi and lower)
 
Discussion starter · #10 ·
Re: Recommended psi is 37. Why? (fmorse)

Dude, 40 psi sounds kind of high. From this post, it sounds like 35-37 psi is the usual pressure level. You said your previous psi level was 35. Have you tried just increasing it to 37?
Also, from what I gathered from this forum, the tpms light could be because of your spare tire. You may want to check this if you haven't already.
Quote, originally posted by fmorse »
Do feel a bit of a difference in the ride.

Is this diffrence for the better or the worse?
 
#11 ·
Re: Recommended psi is 37. Why? (jax2006)

As I mentioned I had the car to the dealer 5 times, the last 2 visits they had a company tech (VW) come to work on the problem of the Tire Preasure Monitor light coming on. I had checked each time the light came on and all tires including spare read 35 psi. Each time the dealer checked them they said the presure was correct. Then on the second visit by VW tech, they advised they are to have the 40 psi in them and then advised me that is what is on the sticker on the door.
I never checked the sticker prior to that as I thought 35 was about right. So now I don't know if this was a way to solve the problem and put a new sticker on the door showing the 40 psi. The car does ride harder. I have a 2007 4motion wagon 3.6. Could someone check and see what their sticker may show and advise. Thanks.
 
#12 ·
In line with the "better mileage" theory, manufacturers are under such pressure to increase their CAFE figures that recommending an increased tire pressure (and testing their vehicles at those tire pressures) is a no-cost way to get some marginal FE.....
 
#15 ·
Re: Recommended psi is 37. Why? (JazzGuyy)

Quote, originally posted by JazzGuyy »
I've got the same vehicle and my door sticker says 40 psi. Anything below that and the TPI light will light up. I know, it happened to me.

I guess that pretty well wraps up this thread (in a good way).
Image
 
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#18 ·
About a month ago our '07 Passat 2.0T Variant had the Tire Pressure monitor lamp come on and the info box said tire pressure was too low. Since I was out of town Wifey took it to the local tire shop and they put in ~30 PSi...box still said pressure was too low. They failed to check the door sticker!??? I set them all to the sticker value (35 PSI) when I got home...tire monitor lamp and message went away. No more problems since then...it really works!
 
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#20 ·
It is clear that different models with different engines and tires all require different air pressure in the tires. The TPMS system seems to demand that the tires have that pressure as a minimum. I know when I accidentally set the tire pressure 5 psi too low the warning light came on and stayed on until I got the tires up to the recommended pressure. There seems to be no "slightly low" allowance.


Modified by JazzGuyy at 6:37 PM 11-17-2006
 
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