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

46 Replies

kohldad
Explorer III
Aug 28, 2019
Running at max only provides a harsher ride and premature wearing of the center. Running to low can cause a catastrophic blowout. So if you aren't sure, run at max.

That said, go to any tire inflation chart for your size tire and use the pressure for your loading. Here is the one for Toyo tires but it's the size and load range that count. Inflation Tables

Though I prefer +10 psi to create a slightly harder sidewall which reduces the sway. If I know I'm going to be doing a lot of mountain back roads, I'll run max to minimize the sway.
Kayteg1
Explorer II
Aug 27, 2019
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. :B
Each reputable tire manufacturer will have inflation chart showing recommendations for the load.
End of the story.
billtex
Explorer II
Aug 27, 2019
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.
twodownzero
Explorer
Aug 27, 2019
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
Navigator II
Aug 27, 2019
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.
Grit_dog
Navigator II
Aug 27, 2019
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.

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Question about tire pressure

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