Question about tire pressure

[MG1912]

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?

[Grit_dog]

^Thread’s dead. Move on bro.

[jadatis]

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]

Grit dog wrote:
5 pages later, ended up at 80 psi in back.....lol

Right.

[Grit_dog]

5 pages later, ended up at 80 psi in back.....lol

[jaycocreek]

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]

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]

I'll try 55 PSI for the front tires and 80 on the rear.

[ryoung]

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]

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]

It was a joke.

[Grit_dog]

billtex wrote:


Does nervous Nellie = experienced?

Nope. = Typical RVnet chicken little responses

[billtex]

MG1912 wrote:
Okay, you buncha nervous Nellies sufficiently spooked me, and I upped the PSI in the rear tires to 80. I go to the CAT scales next week. Wish me luck.

Does nervous Nellie = experienced?

[MG1912]

Okay, you buncha nervous Nellies sufficiently spooked me, and I upped the PSI in the rear tires to 80. I go to the CAT scales next week. Wish me luck.

[Grit_dog]

MG1912 wrote:
Not knowing exactly what my weight is until I go back to the CAT station, we settled on 65 PSI for the front tires and 75 PSI for the rear tires for the time being. Driving from the dealership to my cousin's house (about 30 minutes) was a breeze. In fact, it was more comfortable than driving without the camper. I dialed the Rancho 9000 rear shocks to "max" or "9." I also have Torklift upper StableLoads, and the truck had a factory-installed rear sway bar (puny compared to the Hellwig, but seems to do the job for now).

Sounds about perfect! Motor on!