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A matter of reduced pressure. #4495878
08/23/17 07:40 AM
08/23/17 07:40 AM
Joined: Aug 2011
Posts: 169
Va.
Piston_slap Offline OP
Piston_slap  Offline OP

Joined: Aug 2011
Posts: 169
Va.
On my Ford van I have a decal in the door jam listing the proper size of tire and recommended air pressure.(235*75*15) I run that tire size and have always kept the pressure at the recommended 41psi. I recently had the tires rotated and the shop changed the pressure to 32psi. I noticed the softer ride but was curious what the lower pressure would do to tire wear and longevity? The title shows the weight to be 5400lbs so I don't require the max load capacity of the tires. I value whatever mpg gains I can get. What would you do?


1994 Ford Econoline w/302 & 4R70W
Valvoline 10W-40, Motorcraft FL1
Isotope U235
Re: A matter of reduced pressure. [Re: Piston_slap] #4495890
08/23/17 07:49 AM
08/23/17 07:49 AM
Joined: Oct 2009
Posts: 4,336
Wet side WA
JohnnyJohnson Online content
JohnnyJohnson  Online Content

Joined: Oct 2009
Posts: 4,336
Wet side WA
Well the tire shop is just helping you to your next shopping experience in their store. I always check my tire pressure right after I leave from having my tires rotated.


2004 Corolla 130880
Out: EDGE EP 5W-30 Bosch 3311 7156 Miles
In: Havoline Pro DS 10w-30 Purolator PureOne 3-14-19 129693
2006 Duramax 74725
Out: T6 5W-40 M1-303
In: T6 5W-40 XG9100 73705 4-22-18
Re: A matter of reduced pressure. [Re: Piston_slap] #4495917
08/23/17 08:15 AM
08/23/17 08:15 AM
Joined: Oct 2005
Posts: 7,094
Colorado
Kuato Offline
Kuato  Offline

Joined: Oct 2005
Posts: 7,094
Colorado
Lower pressure will result in slightly lower mpg as the rolling resistance increases.

I've got some experience with tire pressure changes, and instead of even wear, you will likely see the outside of the front tires begin to wear more rapidly than the center. This is more noticeable in heavier vehicles.

The bulk of my experience is from 2000 and 2004 Jeep Grand Cherokees of around 4000 pounds. I bought one with 72k and the other with 18k; both had badly worn outer edges on the front tires, and were inflated to the factory specified 30psi. I immediately went to max rated pressure (35) and kept those tires awhile, until they started washing out in the wet. Upon replacement my new tires were rated for 44psi max; after some experimentation I found that 40-42psi was a pressure that gave even wear as well as noticeably crisper handling.

The ride was not a cushy as it had been before, but for me it was worth it to have tires that kept their wet handling capabilities their entire life and lasted 60k rather than 35k.

You're going to get a lot of opinions on this one, many of which will preach to use the placarded pressure.....so popcorn Ultimately test different pressures and decide for yourself.

Originally Posted By: JohnnyJohnson
Well the tire shop is just helping you to your next shopping experience in their store. I always check my tire pressure right after I leave from having my tires rotated.


Agreed!

Last edited by Kuato; 08/23/17 08:24 AM.

Thick vs Thin test: 15k / 43k miles complete
Re: A matter of reduced pressure. [Re: Piston_slap] #4495938
08/23/17 08:48 AM
08/23/17 08:48 AM
Joined: Jul 2012
Posts: 423
Michigan
khittner Offline
khittner  Offline

Joined: Jul 2012
Posts: 423
Michigan
Your door jamb decal may state that 41psi is the max recommended pressure for the vehicle's max load, or it may simply be a "recommended pressure". If the former, less pressure for less-than-maximum loads may be fine for the longest/most even tire wear. If the latter, pump them back up to Ford's recommended pressure. My local Discount Tire routinely over-fills my tires at rotations on the assumption that I, like most, will pay no attention to their handiwork, and they assume that there will be enough seepage through the alloy wheels over time to bring the pressure down, something 98% of their customers never check between rotations. Most folks don't read the decals on their vehicles.

Re: A matter of reduced pressure. [Re: Piston_slap] #4495945
08/23/17 08:50 AM
08/23/17 08:50 AM
Joined: Apr 2017
Posts: 1,536
Ontario, Canada
mightymousetech Offline
mightymousetech  Offline

Joined: Apr 2017
Posts: 1,536
Ontario, Canada
The tech working on the vehicle is just lazy. Probably sets ALL tires to 32#. We have techs here at the dealer that do the same thing. Drives me mad.


Mighty Mouse Tech
BMW Tech, Former Acura Tech
2010 Civic Si Castrol 0W40, Redline MTL
2013 BMW 135i M Sport Edition Castrol 0W40, Redline MTL
Re: A matter of reduced pressure. [Re: Piston_slap] #4495950
08/23/17 08:55 AM
08/23/17 08:55 AM
Joined: Jun 2016
Posts: 4,254
MN
oil_film_movies Offline
oil_film_movies  Offline

Joined: Jun 2016
Posts: 4,254
MN
True, tire neglect is a problem out there.
Your 41 psi is made for maximum loads with max speeds on that van.
Going down to 32 psi is a bit excessive though. The tire shop was lazy.
I'd allow maybe as low as 35 psi IF you can be sure you aren't using that van to max capacity, and keeping your speeds down to 75 mph max at the lower 35 psi.
If you are loading the van up to max capacity, do use the 41 psi standard.

Re: A matter of reduced pressure. [Re: Piston_slap] #4495954
08/23/17 08:59 AM
08/23/17 08:59 AM
Joined: Mar 2004
Posts: 22,081
Upstate NY
Donald Offline
Donald  Offline

Joined: Mar 2004
Posts: 22,081
Upstate NY
Tire stores techs are not super trained. They just bang on tires and move on to next car.


2015 Subaru Forester 2.5 engine/CVT
2015 Ford F250 w/Powerstroke
2016 Subaru Crosstrek CVT (wife's)
Re: A matter of reduced pressure. [Re: Piston_slap] #4495964
08/23/17 09:12 AM
08/23/17 09:12 AM
Joined: Sep 2008
Posts: 9,264
Ontario, Canada
IndyIan Offline
IndyIan  Offline

Joined: Sep 2008
Posts: 9,264
Ontario, Canada
Are these LT tires? If so you need to run them a bit higher than 32 psi. For P rated tires I find you can up a bit to 35-36 psi without affected NVH too much, so give that a try.


07 Focus ZXW, 5spd manual, 230km M1 5W30
18 Outback 2.5 CVT 22km 0W20
Re: A matter of reduced pressure. [Re: Piston_slap] #4496043
08/23/17 11:22 AM
08/23/17 11:22 AM
Joined: May 2009
Posts: 12,609
N.H, U.S.A.
ARCOgraphite Offline
ARCOgraphite  Offline

Joined: May 2009
Posts: 12,609
N.H, U.S.A.
What I was about to say light truck tires are a different ball of wax than P-metric. Whats the sidewall max pressure of the new ties? 55lbs/sqin gauge?

What tonnage is the van and what do you carry?

Shaggin wagon or work truck?


2019 VW Jetta S,6M OCI#0 2103mi-Castrol Edge Prof? VW508+OE Filter; '17 Subaru Crosstrek CVT OC#6 43467mi-Valvoline Adv 0w20 + SOA Filter
Re: A matter of reduced pressure. [Re: Piston_slap] #4496047
08/23/17 11:24 AM
08/23/17 11:24 AM
Joined: Feb 2013
Posts: 11,429
Phoenix, AZ
Nick1994 Offline
Nick1994  Offline

Joined: Feb 2013
Posts: 11,429
Phoenix, AZ
Inflate to 41 psi. You don't want your van to imitate the Explorers of the 90s and roll over from a blowout.


2015 Hyundai Sonata 2.4L 93k STP Synthetic HM 10w30 & Wix
2000 Toyota Camry 2.2L 233k Mobil Super HM 10w40 & Fram Ultra
1996 Jeep Cherokee 4.0L 148k Mobil 1 HM 10w40 & Fram Ultra
Re: A matter of reduced pressure. [Re: Piston_slap] #4496156
08/23/17 02:05 PM
08/23/17 02:05 PM
Joined: Nov 2008
Posts: 940
Oklahoma
CELICA_XX Offline
CELICA_XX  Offline

Joined: Nov 2008
Posts: 940
Oklahoma
Originally Posted By: Piston_slap
I value whatever mpg gains I can get. What would you do?


Go back to 41 for sure


15 Toyota Prius - M1 EP 0w20 SN+
06 Acura MDX - Valv MaxLife Syn 5w20 SN+
02 Toyota ECHO - Valv MaxLife Syn 5w30 SN+
97 Lexus LX450 - M1 EP HM 5w30 SN+
93 Lexus LS400 - Valv MaxLife Syn 5w30
Re: A matter of reduced pressure. [Re: CELICA_XX] #4496294
08/23/17 05:23 PM
08/23/17 05:23 PM
Joined: Feb 2013
Posts: 434
Nevada, USA
gaijinnv Offline
gaijinnv  Offline

Joined: Feb 2013
Posts: 434
Nevada, USA
Your Econoline came with P235/75R15/XL 108S tires and a recommended Cold Tire Inflation Pressure of 41psi Front/Rear.

For best overall performance, and safety, you should run them at the specified 41psi.

The tire store folks you dealt with do not have a clue ...

Of course, if they put a P-Rated tire that was not XL on, then you are really in trouble - there is no way to inflate a non-XL P-Metric tire to sufficient pressure to meet the minimum load requirements for your Econoline.

HTH

Last edited by gaijinnv; 08/23/17 05:28 PM.

USN NAVSECGRU 1970-1974
Re: A matter of reduced pressure. [Re: Nick1994] #4496593
08/24/17 01:47 AM
08/24/17 01:47 AM
Joined: Feb 2008
Posts: 4,727
Texas
FZ1 Offline
FZ1  Offline

Joined: Feb 2008
Posts: 4,727
Texas
Originally Posted By: Nick1994
Inflate to 41 psi. You don't want your van to imitate the Explorers of the 90s and roll over from a blowout.
This^^^^. Go back to 41.

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