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Highest Safe PSI?
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=24436		 Page 1 of 1
Author:  Bovie [ Mon Sep 17, 2007 3:58 pm ]
Post subject:  Highest Safe PSI?
For best mileage what should my PSI be set at on the stock good years? I think they are right around 32 or 33psi cold now.
Author:  Cowcatcher [ Mon Sep 17, 2007 4:04 pm ]
Post subject: 
38>40 PSI and don't ever go off the pavement.
Author:  Bovie [ Mon Sep 17, 2007 5:59 pm ]
Post subject: 
Thanks,

Stupid add on question but is that 38-40PSI COLD or hot? and what could happen if I go off pavement? Blow out?

Is grass, Packed Gravel, Snow/Ice ok?
Author:  UFO [ Mon Sep 17, 2007 7:12 pm ]
Post subject: 
The tire should list a maximum pressure on the sidewall. Never go over that, but that is a cold pressure.

The PO of my CRD put some serious truck tire on mine, maximum pressure is listed as 80 PSI !! :shock:
So I put them at 40.
Author:  Desert_Busa [ Mon Sep 17, 2007 9:10 pm ]
Post subject: 
Only tires I have seen fail due to too much air was an on the mounting machine. They were at twice the limit and ozone damaged. I run the max sidewall pressure, so long as the tire is wearing evenly. The goodyear st's are happy at 44psi, have a nice even wear pattern, and at 24k show about 50% tread remaining. All of this at 100F+ temps in the valley of the sun. The only reason to run a lower pressure is for ride quality, and maybe braking... but the latter would have to be verified.

Cold is before you drive on them. If driven on, they are hot.

Former tire inspector for a major tire company in AZ.
Author:  ATXKJ [ Mon Sep 17, 2007 9:15 pm ]
Post subject: 
FYI - increasing the tire pressure reduces the rolling resistance which improves mileage - however it comes at a cost - you reduce the contact area of tire to pavement. Therefore you can easily have worse traction, you might find yourself sliding when you should be stopping.
Author:  Cowcatcher [ Mon Sep 17, 2007 9:27 pm ]
Post subject: 
I drove mine about 28K including about 2 miles a day on very nicely improved gravel roads. I have 6 flats, mostly from rock punctures and a blown out front inside sidewall the GY would not warranty at 10K miles. They said I must have hit something and damaged the sidewall.
Author:  Desert_Busa [ Mon Sep 17, 2007 9:28 pm ]
Post subject: 
ATXKJ wrote:
FYI - increasing the tire pressure reduces the rolling resistance which improves mileage - however it comes at a cost - you reduce the contact area of tire to pavement. Therefore you can easily have worse traction, you might find yourself sliding when you should be stopping.


Not entirely accurate. Braking distance has to do with contact patch. Pressure affects contact area. Exaggerated... if you have 5psi in your tires and I have 30 psi. You may stop faster, but risk a blow out. There's a happy medium somewhere, and it's probably around 33psi, but at 44psi the tires are wearing evenly so the change in stopping distance has to be small.

I drive like an old lady, so stopping and accelerating means little to me.
Author:  Ripple [ Tue Sep 18, 2007 6:28 pm ]
Post subject: 
I run my tires at 44PSI, have done so for the last 40K miles. I rotate them every 6k and the tread wear is very good and they still have more than 8/32" tread too. a guy over in the load rating thread called me stupid for running 44PSI. hey it works for me, so thats that.
Author:  CRD_YARP [ Tue Sep 18, 2007 7:33 pm ]
Post subject: 
Summer I prefer 34 psi cold in garage. Pressure will increase to around 39-40 once driven for a few miles. I've gotten my best mileage (29.5 to 30.1) when running it 39/40 psi. That's vs ~27mpg at 33 psi with all other conditions equal.

I've the tire pressure display option. Academically, I knew tire pressure varied. It's rather interesting to see it vary in real time. Particularly when you change directions and reverse which side of the vehicle is in direct sun while driving.

hmmm.... I really spend too much time in this thing.

If off going off pavement for extended time, I'll reduce pressure to increase traction and reduce soil compaction in pastures/fields. Also will adjust target "hot" pressure downward when there's snow/ice on roads.
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