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#4495878 - 08/23/17 07:40 AM A matter of reduced pressure.
Piston_slap Offline


Registered: 08/06/11
Posts: 125
Loc: 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

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#4495890 - 08/23/17 07:49 AM Re: A matter of reduced pressure. [Re: Piston_slap]
JohnnyJohnson Offline


Registered: 10/22/09
Posts: 2353
Loc: 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 Toyota Corolla 119625
Out: QSUD 5W-30 Purolator One 5030 mile OIC
In: 2-8-18 Valvoline ML 5w-30 Fram TG4967 117530
2006 Duramax 73752

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#4495917 - 08/23/17 08:15 AM Re: A matter of reduced pressure. [Re: Piston_slap]
Kuato Offline


Registered: 10/23/05
Posts: 7094
Loc: 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!


Edited by Kuato (08/23/17 08:24 AM)
_________________________
Thick vs Thin test: 15k / 43k miles complete

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#4495938 - 08/23/17 08:48 AM Re: A matter of reduced pressure. [Re: Piston_slap]
khittner Offline


Registered: 07/13/12
Posts: 253
Loc: 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.

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#4495945 - 08/23/17 08:50 AM Re: A matter of reduced pressure. [Re: Piston_slap]
mightymousetech Offline


Registered: 04/03/17
Posts: 1313
Loc: 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
Acura Tech
2010 Civic Si Castrol 0W40, Redline MTL
2013 BMW 135i M Sport Edition Castrol 0W40, Redline MTL

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#4495950 - 08/23/17 08:55 AM Re: A matter of reduced pressure. [Re: Piston_slap]
oil_film_movies Offline


Registered: 06/13/16
Posts: 2223
Loc: 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.

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#4495954 - 08/23/17 08:59 AM Re: A matter of reduced pressure. [Re: Piston_slap]
Donald Offline


Registered: 03/21/04
Posts: 20226
Loc: 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)


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#4495964 - 08/23/17 09:12 AM Re: A matter of reduced pressure. [Re: Piston_slap]
IndyIan Offline


Registered: 09/23/08
Posts: 8889
Loc: 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, 201km M1 5W30
18 Outback 2.5 CVT 2km FF

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#4496043 - 08/23/17 11:22 AM Re: A matter of reduced pressure. [Re: Piston_slap]
ARCOgraphite Offline


Registered: 05/17/09
Posts: 11836
Loc: 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?
_________________________
2014 Nissan Rogue S CVT, OC#9 41392mi-QSUD10W30 + M110A CHAMP Filter; 2017 Subaru Crosstrek CVT OC#2 ?? mi-SOA/Idemitsu 0w20 + SOA Filter

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#4496047 - 08/23/17 11:24 AM Re: A matter of reduced pressure. [Re: Piston_slap]
Nick1994 Offline


Registered: 02/19/13
Posts: 9804
Loc: 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 76k PU 5w30 & OEM
2000 Toyota Camry 2.2L 227k M1 AFE 0w30 & Wix
1996 Jeep Cherokee 4.0L 145k M1 HM 10w40 & Fram Ultra

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#4496156 - 08/23/17 02:05 PM Re: A matter of reduced pressure. [Re: Piston_slap]
CELICA_XX Offline


Registered: 11/28/08
Posts: 861
Loc: 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
02 Toyota ECHO - Valv MaxLife Full Syn 5w30
97 Lexus LX450 - M1 0w40
93 Lexus LS400 - Valv MaxLife Full Syn 5w30

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#4496294 - 08/23/17 05:23 PM Re: A matter of reduced pressure. [Re: CELICA_XX]
gaijinnv Offline


Registered: 02/14/13
Posts: 414
Loc: 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


Edited by gaijinnv (08/23/17 05:28 PM)
_________________________
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#4496593 - 08/24/17 01:47 AM Re: A matter of reduced pressure. [Re: Nick1994]
FZ1 Offline


Registered: 02/07/08
Posts: 4727
Loc: 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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