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Old 04-01-2014, 06:36 AM   #15
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This is the first time I hear of inflating your truck tires to the max. We towed our TT with our 1/2 ton truck for well over 3 years at the suggested pressure on the decal. Never had a problem and it drove great.
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Old 04-01-2014, 09:50 AM   #16
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More pressure much less sway.
i had new tires installed on my 1/2 ton and hooked the 5 th wheel and went 50 miles. It was the worst 50 miles I ever drove with the unit.
Added air and the sway was completely gone.
And that was with a 5th wheel, can't imagine what it would have been with a TT.
My Friend got a new TT and towed it with his 1/2 ton and got scared and bought a dually.
He later pulled the same unit again with the same 1/2 ton and totally regreted buying the bigger truck cause it towed very well with proper tire inflation.
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Old 04-01-2014, 10:12 AM   #17
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Most rims are rated to max weight, not max PSI. Including the rims on my 2012 F-150. If you don't exceed the GVWR of your F-150, then your tires will not be hauling enough weight to worry about exceeding the weight capacity of the rims.

Inflating the tires to 65 PSI will make the F-150 ride harsher than a more reasonable PSI. Weigh the wet and loaded rig on a CAT scale, and inflate the tires to more than enough PSI to handle the weight on the tires - but not much more. Use a load/inflation table for your exact size tires and inflate the tires accordingly, or maybe 5 PSI more than the table calls for. My guess would be 50 PSI in the rear tires and 40 in the front tires will be more than enough.

Your TT will probably gross around 8,000 pounds with tongue weight of around 1,000 pounds. If you haul anything more than a skinny driver in the truck, you'll probably exceed the GVWR of your truck and maybe even the rear GAWR of your truck. But you probably won't exceed the weight capacity of the rear tires when inflated to 50 PSI.

Here's the Tire&Rim Assn (TRA) load/inflation table for LT275/65R18D tires:

PSI... max load per tire on single rims (not duals)
35 ... 1940 lbs.
40 ... 2130
45 ... 2310
50 ... 2535
55 ... 2660
60 ... 2825
65 ... 3000

Note that your tire sidewall says max 3000 pounds weight capacity @ 65 PSI. But you don't need anywhere near 3000 pounds weight capacity. At 50 PSI, you have over 5,000 pounds weight capacity on the two rear tires, and that's a lot more than the rear GAWR of your F-150. At 40 PSI, you have 4,260 pounds of weight capacity on the two front tires, and that's a lot more than the front GAWR of your F-150.

So I would probably run 40 PSI front and 50 PSI rear in your truck when dragging that wet and loaded trailer.
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Old 04-01-2014, 10:51 AM   #18
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Smokey is spot on. When we had our 2010 F150 I put E rated tires on it. Overkill but the deal was too hard to pass up. Anyway, DiscountTire recommended 45psi in the Michelins as that was all that was needed to cover the trucks axle ratings.
Even though the Michelin E rated tires had a max psi of 80 it wasn't needed for the trucks weight carrying abilities.
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Old 04-01-2014, 01:49 PM   #19
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Ok all please forgive me here but I am becoming a bit more confused. I got some actual info off my truck now so hopefully this can help u help me. Unfortunately I don't have my TT until this weekend so actuals from that sticker I don't have yet. Again thank you all for your patience with me as I am just trying to be as safe as I can be.

2012 ford f150 lariat
Super crew 4x4 145" wheel base and factory tow pkg
9300 lb towing capacity
GVWR of 7350lbs
GCWR 15100lbs
Front GAWR 3750lbs @35psi cold
Rear GAWR 3850 @35psi cold

Tire Load Sticker on truck says passenger and cargo weight not to exceed 1476lbs @ 35psi

Tires are Cooper AT3 LT275/65R18 (not OEM)
They are load range C not D as I think I said earlier
Max load of 2635lbs at 50psi

TT info taken from paperwork I have.
DW of 6360lbs
Cargo weight of 2240lbs
HW of 690lbs

From this info can it be said that my truck and my tires are safe enough to tow this trailer?
Also based on all the experience I'm sure most of you have at what tire pressure should I run at?

Again thank you for any help!
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Old 04-01-2014, 01:53 PM   #20
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Sorry forgot to include truck has 3.73 gears
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Old 04-01-2014, 04:23 PM   #21
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As Smokey said above, have your truck scaled with the trailer attached and fully loaded to see where your rear axle weight is at. This will determine what tire pressure you need to be at when towing. I had our Michelin rep stop by to my fleet garage to help address weird tire wear issues I noticed when I started this new job a few months ago. What we found is the original manager had the tires aired up to 100 PSI. Based on the rear axle weight on the ambulances max pressure should be 85 PSI. By over inflating it was causing the center of the tires to bulge up and induce the uneven wear. So based on this, I would suspect that you should be adjusting your tire pressures lower when not towing and then air them up when you are towing. Kind of a pain, but should help promote proper tire wear.
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Old 04-01-2014, 05:28 PM   #22
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I would make sure your tires are @50psi as it looks like you will be maxed out on RAWR. A 6360lb dry TT will be 7300lbs loaded. That works out to about 900lbs for tongue weight. With only 1476lbs of payload that only leaves you with 576lbs for passengers and gear you take in the truck. If you have a cap or something else like that on the truck then you have even less to work with.
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Old 04-01-2014, 08:08 PM   #23
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Quote:
Originally Posted by RyRo70 View Post
Tires are Cooper AT3 LT275/65R18 (not OEM)
They are load range C not D as I think I said earlier
Max load of 2635lbs at 50psi
...
Also based on all the experience I'm sure most of you have at what tire pressure should I run at?
My answer doesn't change. "So I would probably run 40 PSI front and 50 PSI rear in your truck when dragging that wet and loaded trailer."

What changes is you no longer have the option to run more than 50 PSI. The same load/inflation table still applies, but all PSI more than 50 must be ignored.

Quote:
From this info can it be said that my truck and my tires are safe enough to tow this trailer?
Depends on your definition of "safe". You'll be overloaded over the GVWR and maybe over the rear GAWR of your truck. Some folks would say that's not safe.
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Old 04-01-2014, 10:02 PM   #24
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This from a actual tire engineer CapriRacer on Open Roads forums;

LT requires 15 psi increase above P tire pressure;

"The maximum pressure is not the same as where the load carrying capacity maxes out. On P metric Standard Load tires, the load carrying capacity increases as the inflation pressure increases - up to 35 psi. "
And
The maximum usage pressure for a Standard Load P metric tire might not be 35 psi - it might be 44 or 51 psi, but that doesn't change the relationship between the pressure and the load."

What CapriRacer is saying, who is one of the contributing tire engineers Barry Smith on Allexperts.com , the LT tire will have to be increased to 50 psi to carry the same load as the P tire at 35 psi. Just about any tire manufacturers air pressure/load charts shows this.
And increasing air pressure from 35 psi to 44 psi in the P tire doesn't change the tires load capacity as it maxed at 35 psi. More pressure does stiffen the tire carcass/sidewalls for towing/hauling duties.
When you change tire sizes/load ranges the tire placard air pressure doesn't work. Placard air pressure recommendations works on the OEM tires only.
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Old 04-01-2014, 11:05 PM   #25
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Quote:
Originally Posted by jamesrxx951 View Post
As Smokey said above, have your truck scaled with the trailer attached and fully loaded to see where your rear axle weight is at. .
+1

My guess is with 2 adults and nothing in the back of the truck you'll be just within oem limits. That's a very heavy trailer for a 1/2 ton. As stated, your tires will be fine if inflated at 50 psi. When going from p metric to LT, you add 15psi from the vehicle's tire sticker.

When I got my F150 home I was shocked that that the axle limit on the rear will be reached before the gvwr limit... I guess Ford expects the driver and front passenger to be pretty heavy.
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