My 2007 Ford F350 6.0 supercab long bed SRW has Nitto Terra Grappler G2 A/T LT295/70R18 E 129/126Q tires front and rear. The truck came with 275/70R18 LRE tires, which were replaced by the previous owner. I wrote to Nitto to ask them about recommended tire pressures for my truck camper application (~3,000 on front axle and ~7,000 on the rear axle). I received what seemed to me like a lawyerly response:"Based on the information provided, the calculated pressure for your Terra Grappler G2 tires is 65 PSI cold pressure on the front tires and 68 PSI cold pressure on the rear tires. At these inflation pressures, your tires are supporting the same amount of weight as your OEM tires did per the vehicle manufacturer's specifications. For any increase in pressure due to towing, we would recommend referring to your vehicle owner's manual for any instructions."I was surprised because I would have thought they'd recommend closer to 80 PSI for the rear tires. Is their response cautious due to liability concerns? The reference to OEM tires and the vehicle owner's manual makes me suspect this. Or do the recommended pressures sound right?

Put 80 in the back tires. No question. 68 is probably the min pressure off the chart for exactly 7000lbs. But once you're loaded up for a year on the road, 7k is probably a bit light. 65 is about max what you'd want in front but not excessive. With those big tires, maybe a bit lower if it feels rough.

Purely from a rated capacity, the rims are technically the weak link in the equation, but nothing to worry about IMO. Whole lot of trucks hauling that much weight or more every day on OE rims.

The pressures recommended seem fine. Bigger tires have more air volume with supports more weight with less pressure. Remember, pressure = force / area. That said, I always air my rear tires up all the way when loaded heavy. I have been running lower pressures in the front though as recommended by the manufacturer, and found that the truck rides better and the tires don't get hot. Also, always check your spare when checking your tire pressures.

Grit dog wrote:Put 80 in the back tires. No question. 68 is probably the min pressure off the chart for exactly 7000lbs. But once you're loaded up for a year on the road, 7k is probably a bit light. 65 is about max what you'd want in front but not excessive. With those big tires, maybe a bit lower if it feels rough.This.There is no down-side to running at the max in the rear.Front likely sees very little added load with TC-if any-and you could run these lower.I run rear at 80psi and front at 55 psi.

billtex wrote:.There is no down-side to running at the max in the rear..Yes, there is and I have dental bills to prove it. :BEach reputable tire manufacturer will have inflation chart showing recommendations for the load. End of the story.

Question about tire pressure | Good Sam Community

Grit_dog
Navigator
Sep 12, 2019
^Thread’s dead. Move on bro.
jadatis
Explorer
Sep 12, 2019
MG1912 wrote:

I went to the CAT scale today with all my gear, full tank of diesel, full cassette reservoir (3 gallons), and full fresh water tank (40 gallons). Looks like I'm under my GAWR for the axles, but very slightly over GVWR.

With this new information, I recalculated.
Apeared to be singleload behind.
Not lowered, for offroad, as I did in first calc, it gave F52psi , R 73 psi.
When lowered with my pigheaded system, F 67 psi , R 95 psi( wich is not allowed anymore, so 80 psi) .
Then in the end 65/ 80 psi has not been a bad guess.

But can you give me , if your tires have those profileblocks, that cover part of sidewall or not.
billtex
Explorer II
Sep 12, 2019
Grit dog wrote:
5 pages later, ended up at 80 psi in back.....lol

Right.
Grit_dog
Navigator
Sep 11, 2019
5 pages later, ended up at 80 psi in back.....lol
jaycocreek
Explorer II
Sep 11, 2019
I run 75 in the rear/80 max and 65 in the front/70 max per recommendation from my tire dealer with my TC...Just got back from them and the mysterious inside dually extension disappearance on one side..
kohldad
Explorer III
Sep 11, 2019
Think you will find the 55 psi for the front a bit too low as you will be really scuffing the tires on the corners. 65 psi will probably work out abut right and give you better feel when cornering. I only need 55 psi but feel the steering is soft and mushy, especially on back country and mountain roads. For mainly interstate driving, 65 feels good, but if I know I'm going to be doing a lot of twisty mountain roads, I bump it up to 70 or 75.

Good choice on the rear psi.
MG1912
Explorer
Sep 11, 2019
I'll try 55 PSI for the front tires and 80 on the rear.
ryoung
Explorer
Sep 11, 2019
MG1912, now that you know your axle weights, you can go to the link I provided earlier and find that the manufacture gave you the correct air pressure response to your initial inquiry.

You don't need 80 psi as some suggested.

https://tirepressure.com/nitto-terra-grappler-g2-tire-pressure

ryoung
MG1912
Explorer
Sep 11, 2019

I went to the CAT scale today with all my gear, full tank of diesel, full cassette reservoir (3 gallons), and full fresh water tank (40 gallons). Looks like I'm under my GAWR for the axles, but very slightly over GVWR.
MG1912
Explorer
Sep 07, 2019
It was a joke.