It is currently Sat Sep 13, 2025 8:28 am

All times are UTC - 5 hours [ DST ]




Post new topic Reply to topic  [ 10 posts ] 
Author Message
 Post subject: Highest Safe PSI?
PostPosted: Mon Sep 17, 2007 3:58 pm 
Offline
LOST Member

Joined: Sun Jul 23, 2006 2:37 am
Posts: 164
Location: Bellingham, WA
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.

_________________
2006 Jeep Liberty CRD Limited
1983 Mercedes Benz 240D


Top
 Profile  
 
 Post subject:
PostPosted: Mon Sep 17, 2007 4:04 pm 
Offline
Lifetime Member
Lifetime Member
User avatar

Joined: Sat Apr 15, 2006 12:56 pm
Posts: 1830
Location: Spokane, WA
38>40 PSI and don't ever go off the pavement.

_________________
Dave

'06 CRD Limited, Lt. Khaki, MOPAR Slush Mats/Skids, DrawTite Front Hitch, Mag Lite, Yakima Bars, Thule Bike Rack, Fumoto, ORM, 245/70 Revo 2

Wish list: Lift, Boulder Bars, Something Bigger in the Front and Back, More Lights


Top
 Profile  
 
 Post subject:
PostPosted: Mon Sep 17, 2007 5:59 pm 
Offline
LOST Member

Joined: Sun Jul 23, 2006 2:37 am
Posts: 164
Location: Bellingham, WA
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?

_________________
2006 Jeep Liberty CRD Limited
1983 Mercedes Benz 240D


Top
 Profile  
 
 Post subject:
PostPosted: Mon Sep 17, 2007 7:12 pm 
Offline
Lifetime Member
Lifetime Member
User avatar

Joined: Wed Apr 18, 2007 6:25 pm
Posts: 1306
Location: Colorado USA
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.

_________________
'05 Liberty CRD B100, SEGR - SOLD

'01 Beetle TDi B100, EGR delete
'83 Mercedes 240D B100, no EGR

--- SEGR Builder ---


Top
 Profile  
 
 Post subject:
PostPosted: Mon Sep 17, 2007 9:10 pm 
Offline
LOST Newbie

Joined: Mon May 08, 2006 8:29 pm
Posts: 87
Location: Chandler, AZ
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.

_________________
'06 White Limited CRD born on 08/05 37k miles F37'd
mods:: vented, exhausted, ORM, cat 2, Lifted
Other Rides:: CJ7 Limited, and many bikes


Last edited by Desert_Busa on Mon Sep 17, 2007 9:17 pm, edited 1 time in total.

Top
 Profile  
 
 Post subject:
PostPosted: Mon Sep 17, 2007 9:15 pm 
Offline
Lifetime Member
Lifetime Member
User avatar

Joined: Thu Dec 29, 2005 9:59 pm
Posts: 5171
Location: Austin, TX
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.

_________________
2005 CRD
stuff
Skeptic quod gratis asseritur, gratis negatur


Top
 Profile  
 
 Post subject:
PostPosted: Mon Sep 17, 2007 9:27 pm 
Offline
Lifetime Member
Lifetime Member
User avatar

Joined: Sat Apr 15, 2006 12:56 pm
Posts: 1830
Location: Spokane, WA
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.

_________________
Dave

'06 CRD Limited, Lt. Khaki, MOPAR Slush Mats/Skids, DrawTite Front Hitch, Mag Lite, Yakima Bars, Thule Bike Rack, Fumoto, ORM, 245/70 Revo 2

Wish list: Lift, Boulder Bars, Something Bigger in the Front and Back, More Lights


Top
 Profile  
 
 Post subject:
PostPosted: Mon Sep 17, 2007 9:28 pm 
Offline
LOST Newbie

Joined: Mon May 08, 2006 8:29 pm
Posts: 87
Location: Chandler, AZ
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.

_________________
'06 White Limited CRD born on 08/05 37k miles F37'd
mods:: vented, exhausted, ORM, cat 2, Lifted
Other Rides:: CJ7 Limited, and many bikes


Top
 Profile  
 
 Post subject:
PostPosted: Tue Sep 18, 2007 6:28 pm 
Offline
LOST Member

Joined: Fri Jan 13, 2006 6:27 pm
Posts: 172
Location: Toledo Ohio
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.


Top
 Profile  
 
 Post subject:
PostPosted: Tue Sep 18, 2007 7:33 pm 
Offline
LOST Newbie

Joined: Sun Sep 16, 2007 11:40 pm
Posts: 7
Location: Missouri
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.

_________________
05 CRD Ltd with 81K since 5/6/2005
1st EGR & oil plug at 20K, partial F37 at 60K
2nd EGR, MAP sensor, and turbo hose at 75K (also switched to Rot Syn 5w40)
rattles/shudders from day one, also delays before moving on cold start

93 F-250 7.3L Cummins (non-turbo), currently 245K
rusty, but it's never needed a software upgrade


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 10 posts ] 

All times are UTC - 5 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 35 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to:  
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group. Color scheme by ColorizeIt!
Logo by pixeldecals.com