96 850 GLT Tire Pressure info?

turbotim2 · Post by **turbotim2** » 14 Jun 2007, 07:43

Well it sounds to me like 36 F and 41 R are preferred and the 31 F 32 R are optional (meaning second choice, thus the "option").

zenmervolt · Post by **zenmervolt** » 14 Jun 2007, 10:12

JRL wrote:
turbotim2 wrote:I just looked at mine and it says 36 front, 41 rear. I run mine at 35 though.
You guys do NOT know how to read these.
When driving alone or with one others you use THE OPTIONAL pressure which is about 32 or so.
The "standard pressure" is for a fully loaded up vehicle, READ the labels

No.

The "standard" pressure is for an up to fully-loaded vehicle. The optional pressure is unsafe at rated capacity.

If you use the standard pressure with one person in the car, no harm is done. If you use the optional pressure on a fully-loaded car (even if it's just 4 people) you risk overheating the tires and having a blowout. It's not a big risk, and it's not likely to happen, but it's still a risk.

Even beyond that though, the stickers are recommendations, not prescriptions. They are a starting point. I run 40 PSI front and 36 PSI rear on my own car. This increases the grip at the front and decreases grip at the rear, which mitigates (slightly) the car's strong understeer.

damnyankee · Post by **damnyankee** » 15 Jun 2007, 21:50

45 psi front and rear
rides tight, helps mpg trade off

Crunchies · Post by **Crunchies** » 15 Jun 2007, 21:51

JRL >>> Your absolutely correct!

turbotim2 · Post by **turbotim2** » 16 Jun 2007, 04:49

Actually you may just want to read the tire manufacturer's recommendations as most of the tires that fit on these cars state a max psi of 35 anyway. So if you do go over it you may void any warranty you have on the tires.

As a side note, everyone does something different and will never agree with another person on here so do whatever you feel is best. I don't know how many other people that read this are mechanics but my guess based on answers you see is that there are few.

zenmervolt · Post by **zenmervolt** » 16 Jun 2007, 11:03

turbotim2 wrote:Actually you may just want to read the tire manufacturer's recommendations as most of the tires that fit on these cars state a max psi of 35 anyway. So if you do go over it you may void any warranty you have on the tires.

It's been a long time since I've seen a name brand tire (Bridgestone, Firestone, Goodyear, Michelin) that listed 35 PSI as its maximum pressure. At least for the S70 T5 I have the only tires I found available from Bridgestone/Firestone in the OE size have a maximum cold pressure of 44 PSI. (Always fill tires and check pressure when the car has been driven less than 1/2 mile or has been allowed to sit for at least one hour after driving since the recommended pressures are cold pressures.)

You make a good point about checking the tire though. It's just plain unsafe to run the tire at a higher cold pressure than is listed on the sidewall.

All of this said, manufacturer's recommended tire pressures are just that, recommendations. They are balancing things like treadwear and ride comfort and should essentially be treated as a minimum pressure and not a hard and fast number. You can safely run pressures that are different (higher) than the manufacturer's recommendation as long as you do not exceed the tire's own maximum cold pressure.

Tsquared · Post by **Tsquared** » 16 Jun 2007, 11:13

Something else to consider. Grab a couple of air pressure gauges and go check your tire pressure. Notice that they probably will read differently. The free gauge you received from wherever next to the fancy high dollar dial gauge are probably both wrong but both are in the general ballpark of where you want to be. The point is that most gauges are not calibrated and can be off quite a bit.

Trilarry · Post by **Trilarry** » 16 Jun 2007, 19:15

Very Good point T, We have to take our gauges to PMEL every 6 weeks or so for calibration for Aircraft specs. They are always plus or minus 5 even after calibration.
Tri

Post by **JRL** » 16 Jun 2007, 20:16

You guys are wrong.
The optional pressure is lower and is the one to use most of the time
As for the manufacturers max. tire pressure all that means is not go over that under any circumstances, it does NOT mean to run it.
There was a lot of confusion in the beginning when they started to put them on the tires but later on the manufacturers came out with a bulletin to that effect.
The pressure you use (IS THE ONE ON THE GAS LID DOOR) or wherever it may be on whatever car, heck, some are in the trunk!
If you read it CAREFULLY it will state fully loaded, non loaded, etc
If you choose to use 35-38 on a Volvo, knock yourself out, it won't hurt anything except perhaps your kidneys, then enjoy the rattles the car will develop, I guarantee
disclaimer:
(unless you live in FL, where the roads are so smooth, nothing ever rattles)

and this:

"No
The "standard" pressure is for an up to fully-loaded vehicle. The optional pressure is unsafe at rated capacity"
is pure crap and incorrect

turbotim2 · Post by **turbotim2** » 17 Jun 2007, 05:52

Geez JRL, sound slike your ready for your bottle and a nap.

Both min and my wife's Michelins have a max 35 psi so I won't go over it. and lets face it, these are family sedans or wagons with already fairly poor performance so what is 3 psi going to really do? Exactly, nothing.