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04-07-2019, 05:06 PM
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#1
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Senior Member
Join Date: Jan 2014
Posts: 241
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max air pressure
Ford F150 SCrew, max tow pkg, 20 " tires. Towing 7000 lbs trailer.
Truck has Michelin 275/55/R20 LT, tire has max PSI 44 on sidewall.
Run 35 PSI as daily driver and inflate to 44 PSI when towing?
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04-07-2019, 05:31 PM
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#2
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Senior Member
Join Date: Jun 2012
Location: Southern NM
Posts: 9,523
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Thats what most folks do. At least the back tires at max cold psi. Front can run a little less.
__________________
Scott and Liz - Southern NM
2012 Wildcat Sterling 32RL - w/level up (best option ever)
2007 Chevy 2500HD Duramax
Reese Fifth Airborne Sidewinder
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04-08-2019, 10:07 AM
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#3
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Senior Member
Join Date: Jan 2014
Posts: 241
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max psi
Michelin says 35 psi as printed on door jam, ford dealer says 35psi for all four tires, 35psi is based on fully loaded truck with payload of 1732.
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04-08-2019, 10:15 AM
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#4
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Senior Member
Join Date: May 2016
Location: Yellowknife
Posts: 1,162
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Quote:
Originally Posted by swj
Michelin says 35 psi as printed on door jam, ford dealer says 35psi for all four tires, 35psi is based on fully loaded truck with payload of 1732.
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Correct. Nothing wrong with going to 44 if you find it helps a little.
__________________
2007 Rockwood 2701SS
2017 Ram 2500 Granite Crystal SAP Laramie 6.7L
2014 Triumph Bonneville. NH Togas, tuned
1953 GMC 9314
1982 GoldWing Interstate
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04-08-2019, 11:08 AM
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#5
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Member
Join Date: Jul 2016
Location: Parrish Florida
Posts: 46
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The tire's max load rating is achieved at the PSI listed on the door tag. Adding more air will not help carry more weight, but it may help eliminated some of the "wobbly" feeling reported when trailer is at full weight. Perfectly safe to put more in and see if you like it better.
__________________
2021 Palamino Puma 31FKRK ( Seasonal)
2018 GMC Sierra 1500 5.3 Max Tow
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04-08-2019, 11:11 AM
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#6
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Senior Member
Join Date: Jun 2012
Location: Southern NM
Posts: 9,523
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I don't give the door sticker for tire pressure much credence. They are usually either good for non-towing, towing, or neither.
Good example is my current truck. Max cold psi is 80 on the tire. Door sticker says 55psi front, 80psi back. At 55psi the fronts look flat (heavy diesel), handling and steering is just bad. 80psi for rear is great for towing, terrible for ride when not towing. This door sticker makes no sense to me.
So when not towing I run 65psi front, 60-65 rear. When towing I run 70 front, 80 rear.
You will get lots of opinions on what is correct. I'm just telling you what I do. Pick a psi that works for you and your situation (loaded, unloaded). Somewhere between door sticker and tire max cold psi is a good starting place.
__________________
Scott and Liz - Southern NM
2012 Wildcat Sterling 32RL - w/level up (best option ever)
2007 Chevy 2500HD Duramax
Reese Fifth Airborne Sidewinder
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04-08-2019, 11:14 AM
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#7
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Pickin', Campin', Mason
Join Date: Aug 2015
Location: South Western PA
Posts: 19,074
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Quote:
Originally Posted by NMWildcat
I don't give the door sticker for tire pressure much credence. They are usually either good for non-towing, towing, or neither.
Good example is my current truck. Max cold psi is 80 on the tire. Door sticker says 55psi front, 80psi back. At 55psi the fronts look flat (heavy diesel), handling and steering is just bad. 80psi for rear is great for towing, terrible for ride when not towing. This door sticker makes no sense to me.
So when not towing I run 65psi front, 60-65 rear. When towing I run 70 front, 80 rear.
You will get lots of opinions on what is correct. I'm just telling you what I do. Pick a psi that works for you and your situation (loaded, unloaded). Somewhere between door sticker and tire max cold psi is a good starting place.
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^^This^^ is my mode of operation as well.
__________________
2022 Cedar Creek 345IK 5th Wheel•Solar & Inverter•2017 Ford F-Series SCREW 4x4•Factory Puck•B&W Companion•TST Tire Monitor w/Repeater•Sinemate 3500w Gen.
F&AM Lodge 358 Somerset, PA - JAFFA Shrine - Altoona, PA
Days Camped ☼ '19=118 ☼ '20=116 ☼ '21=123 ☼ '22=134 ☼ '23=118☼ '24=86
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04-08-2019, 11:18 AM
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#8
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Member
Join Date: Jul 2016
Location: Parrish Florida
Posts: 46
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Just a FYI. My first sentence was a fact. Everything after that was an opinion.
__________________
2021 Palamino Puma 31FKRK ( Seasonal)
2018 GMC Sierra 1500 5.3 Max Tow
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04-08-2019, 12:22 PM
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#9
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Senior Member
Join Date: Feb 2018
Location: Monticello, IL
Posts: 1,696
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Quote:
Originally Posted by alb2tpa
The tire's max load rating is achieved at the PSI listed on the door tag. Adding more air will not help carry more weight, but it may help eliminated some of the "wobbly" feeling reported when trailer is at full weight. Perfectly safe to put more in and see if you like it better.
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Quote:
Originally Posted by alb2tpa
Just a FYI. My first sentence was a fact. Everything after that was an opinion.
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Sorry, you're incorrect or misstated what you were trying to say.
The TRUCK'S max load rating can be achieved at the PSI listed on the door/pillar tag, meaning the factory tires can carry the truck's GVWR/GAWR at the PSI listed on the truck's tag. The TIRE'S max load rating is achieved at the PSI listed on the tire.
The TRUCK tag PSI has nothing to do with the TIRE'S MAX load rating. The tires absolutely can carry more weight if more pressure is added above the truck's tag PSI (provided the tag PSI is not the same as the tire's max load PSI) but that does not increase the TRUCK'S load capacity.
__________________
2017 GMC Canyon - CCLB, 4x4, 2.8L Duramax, ARE Z-series shell
2013 Shamrock 21SS
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04-08-2019, 12:40 PM
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#10
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Senior Member
Join Date: May 2017
Posts: 5,712
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Very similar to what I did with 1500 Silverado and old Jayco. Close to the same weight..
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04-08-2019, 01:10 PM
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#11
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Senior Member
Join Date: Jan 2014
Posts: 241
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Sorry, you're incorrect or misstated what you were trying to say.
The TRUCK'S max load rating can be achieved at the PSI listed on the door/pillar tag, meaning the factory tires can carry the truck's GVWR/GAWR at the PSI listed on the truck's tag. The TIRE'S max load rating is achieved at the PSI listed on the tire.
The TRUCK tag PSI has nothing to do with the TIRE'S MAX load rating. The tires absolutely can carry more weight if more pressure is added above the truck's tag PSI (provided the tag PSI is not the same as the tire's max load PSI) but that does not increase the TRUCK'S load capacity.
SO... I talked to Michelin and my Ford Dealer, the max 35 PSI on door jam is the correct air pressure based on the truck being loaded at the full payload weight of 1732 llbs which is also on the door jam... I am going to leave my air pressure at 35PSI.
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04-08-2019, 01:26 PM
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#12
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Senior Member
Join Date: Jun 2012
Location: Southern NM
Posts: 9,523
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Quote:
Originally Posted by swj
Sorry, you're incorrect or misstated what you were trying to say.
The TRUCK'S max load rating can be achieved at the PSI listed on the door/pillar tag, meaning the factory tires can carry the truck's GVWR/GAWR at the PSI listed on the truck's tag. The TIRE'S max load rating is achieved at the PSI listed on the tire.
The TRUCK tag PSI has nothing to do with the TIRE'S MAX load rating. The tires absolutely can carry more weight if more pressure is added above the truck's tag PSI (provided the tag PSI is not the same as the tire's max load PSI) but that does not increase the TRUCK'S load capacity.
SO... I talked to Michelin and my Ford Dealer, the max 35 PSI on door jam is the correct air pressure based on the truck being loaded at the full payload weight of 1732 llbs which is also on the door jam... I am going to leave my air pressure at 35PSI.
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*sigh* They have to say that . Sounds like you made a decision, so that's good. See how it feels while towing, experiment a little. Good thing is, you can always change your mind later; or not
__________________
Scott and Liz - Southern NM
2012 Wildcat Sterling 32RL - w/level up (best option ever)
2007 Chevy 2500HD Duramax
Reese Fifth Airborne Sidewinder
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04-08-2019, 01:26 PM
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#13
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Pickin', Campin', Mason
Join Date: Aug 2015
Location: South Western PA
Posts: 19,074
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Quote:
Sorry, you're incorrect or misstated what you were trying to say.
The TRUCK'S max load rating can be achieved at the PSI listed on the door/pillar tag, meaning the factory tires can carry the truck's GVWR/GAWR at the PSI listed on the truck's tag. The TIRE'S max load rating is achieved at the PSI listed on the tire.
The TRUCK tag PSI has nothing to do with the TIRE'S MAX load rating. The tires absolutely can carry more weight if more pressure is added above the truck's tag PSI (provided the tag PSI is not the same as the tire's max load PSI) but that does not increase the TRUCK'S load capacity.
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Quote:
Originally Posted by swj
SO... I talked to Michelin and my Ford Dealer, the max 35 PSI on door jam is the correct air pressure based on the truck being loaded at the full payload weight of 1732 llbs which is also on the door jam... I am going to leave my air pressure at 35PSI.
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Again... don't miss the fact (as DieselDrax eloquently pointed out) that the TIRES can carry more load than the door sticker says as verified by the 44 PSI MAX inflation. That doesn't mean the TRUCK can... but it also doesn't mean that adding air to the TIRES stated MAX inflation point (on the sidewall) will hurt the tire in any way.
__________________
2022 Cedar Creek 345IK 5th Wheel•Solar & Inverter•2017 Ford F-Series SCREW 4x4•Factory Puck•B&W Companion•TST Tire Monitor w/Repeater•Sinemate 3500w Gen.
F&AM Lodge 358 Somerset, PA - JAFFA Shrine - Altoona, PA
Days Camped ☼ '19=118 ☼ '20=116 ☼ '21=123 ☼ '22=134 ☼ '23=118☼ '24=86
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04-08-2019, 03:52 PM
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#14
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Member
Join Date: Jul 2016
Location: Parrish Florida
Posts: 46
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From tirereview.com
They also set each tire’s “load curve,” which is the relationship between inflation pressure and the tire’s maximum load carrying capacity. Like the size standards, there are some slight variations among the different organizations’ load curves, but they are not significant.
Part of each load curve standard is the point at which the load curve stops going up. For TRA p-metric standard load tires, it is at 35 psi. Equivalent ETRTO and JATMA tires peak at 36 psi. Interestingly, all of the standardizing organizations agree that standard load passenger car tires can (and should) use optional higher inflation pressures (44 psi or 51 psi) for certain circumstances such as high speed driving. However, these higher inflation pressures generally provide no increase in load carrying capacity and in some circumstances specify a reduction in load for high speed driving.
Since the OP has a P metric tire, just like I do, the FACT is, he has no more load carrying capacity at 44 or 51psi than he does at 35psi.
__________________
2021 Palamino Puma 31FKRK ( Seasonal)
2018 GMC Sierra 1500 5.3 Max Tow
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04-08-2019, 04:12 PM
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#15
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Senior Member
Join Date: Feb 2018
Location: Monticello, IL
Posts: 1,696
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Quote:
Originally Posted by alb2tpa
From tirereview.com
They also set each tire’s “load curve,” which is the relationship between inflation pressure and the tire’s maximum load carrying capacity. Like the size standards, there are some slight variations among the different organizations’ load curves, but they are not significant.
Part of each load curve standard is the point at which the load curve stops going up. For TRA p-metric standard load tires, it is at 35 psi. Equivalent ETRTO and JATMA tires peak at 36 psi. Interestingly, all of the standardizing organizations agree that standard load passenger car tires can (and should) use optional higher inflation pressures (44 psi or 51 psi) for certain circumstances such as high speed driving. However, these higher inflation pressures generally provide no increase in load carrying capacity and in some circumstances specify a reduction in load for high speed driving.
Since the OP has a P metric tire, just like I do, the FACT is, he has no more load carrying capacity at 44 or 51psi than he does at 35psi.
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The OP does not have a P-metric tire, they have an LT tire. Also, Michelin specifically states that max load for a 275/55/R20 LT tire, like their LTX M/S2, is at 44psi. In the case of this tire, it's 2,304LB @ 44psi. Not 35psi. Not 51psi.
Running the same tire at 35psi will have enough load capacity for the TRUCK MAX WEIGHT but the tires ARE NOT at the PSI needed for the TIRE MAX CAPACITY.
Tire max weight capacity is at the sidewall PSI and not the vehicle placard PSI. Period.
__________________
2017 GMC Canyon - CCLB, 4x4, 2.8L Duramax, ARE Z-series shell
2013 Shamrock 21SS
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04-08-2019, 05:04 PM
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#16
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Senior Member
Join Date: Jan 2014
Posts: 241
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so, if you increase PSI to 40, any safety concerns, do you get a better ride?
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04-11-2019, 12:50 PM
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#17
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Senior Member
Join Date: Mar 2014
Posts: 3,083
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Quote:
Originally Posted by swj
so, if you increase PSI to 40, any safety concerns, do you get a better ride?
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I tow my A-frame (about 3100 lbs loaded) with my 2008 Hyundai Entourage minivan (rebadged Kia Sedona) with over 200K miles on it. I use an E-2 600/6000 WDH to improve the towing experience and keep weight on the front end of the minivan.
The minivan has Michelin ZX P-metric tires. Door placard pressure is 35PSI. I consider this my minimum pressure (not towing I like 36-37PSI). When towing, I use 38-40 PSI, exact PSI depends where we are going elevation-wise and temperature-wise. If I'm headed Texas (6K ft lower) in the cooler months, I will use 39-40PSI. If I'm going in the summer or am going up in the Rockies, I like 37-38PSI.
Unloaded, I find 38+PSI to not cushion the minivan's ride as well. I set the tire pressures before every camping trip, and monthly if no camping trips are taken.
My tires wear evenly across the tread, which is the best indicator I'm getting it close to where it should be.
just my experiences
Fred W
2019 Flagstaff T21TBHW A-frame
2008 Hyundai Entourage minivan
camping Colorado and adjacent states one weekend at a time
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