I have seen over 5K on my front axle with a relativle empty bed.. 9K total weight. Just some hunting gear and an elk..

50 still is quite low for 2,230 lbs/tire. That is 70% of the tires rated capacity at 62% of its air (what really holds the weight)

 

That is 70% of the tires rated capacity at 62% of its air (what really holds the weight)

What I was told was that tire sidewall numbers are fairly meaningless versus actual pressure rise after a steady state is achieved. Assuming proper tire rating for vehicle, dialing in the pressure seems to be key.

Problem is that climate, road condition, vehicle weight, altitude, etc, etc, are all going to vary.

Went out to check door sticker (note truck in sig)

FF GAWR 4,750 -- 50 psi
RR GAWR 6,000 -- 70 psi

Manual says 9,000 GVWR. Truck, empty, 50/50 for pressure.

I've been meaning to check the pressure rise after 1.5-hrs steady state driving next 700-mile roundtrip. Truck stays around 7400-empty (the usual trunk junk) and goes up past 8,000 on some return trips. Tire wear was 2/32 first 23,000 miles.

I've experimented (temperature) with raising FF tires to 55 and to 60. No appreciable change. I've done the same with rear, to 80. Same result. Harder ride, but same temps. I don't have the scale tickets handy.

What I know for a certainty is that 70-psi in rear causes terrible handling characteristics when empty. Might be different for 4WD, as the 2WD is IFS.

I've had the truck up near 9,000 several times and 50/70 FF/RR has proven fine so far.

Looking forward to some consensus on temps/pressures if it is possible, or, DO NOT EXCEED! will work fine if we can get it.

 

I dont think I can agree with the sidewall numbers being meaningless. They are cold temps, I am certain the tire mfgrs know how much your tires will increase in psi at max load at 80mph, thats all factored into the cold psi and weight rating.. (Which makes me wonder if Nitrogen doesn't decrease tire capacity as the tested psi increase may not be there??)

I didn't know the GAWR on a 2wd was lower than 4wd, could account for the lower requied psi's.

 

meaningless

Okay, too strong a word. But I notice people using it as a default number all the time, and that isn't AT ALL what I was given to understand. The idea that it's okay to jack up the pressure to that number is the problem as the vehicle isn't configured for that use (more of a meet's the requirements kind of number) UNLESS the vehicle manufacturer indicates such. Or, an opinion from a tire manufacturer (who isn't likely to tangle with a big customer).

The big trucks I've driven had service departments with VERY strict requirements about pressure. The close competitor (with seemingly identical equipment) had a different number. All of it based on examination of thousands of carcasses with tire reps constantly at the main yard.

So far as I can tell thus far, maintain factory pressures on proper replacement tires (size, capacity, etc) and a tire temp default of 157F.

Be nice if we had more in depth, but I imagine it's going to work out per vehicle (given a low pressure rise after steady state driving with a given load).

 

Okay I understand what you are saying...

I am someone who varies my tire pressure all the time, empty, partial loads, full loads, towing, etc... My general rule of thumb is as much pressure as I can run with a flat tread pattern.

 

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(Article) OVERDRIVE Magazine 12/2008

"Matching Tire Pressure to Load" (John Baxter)

The tire’s contact patch should be as large as possible while keeping a healthy amount of pressure and maintaining even contact between all the areas of the patch and the road. That means adjustment to reach “the optimal pressure for the load,” rather than inflating the tire to the same cold pressure all the time, says Doug Jones, customer engineering support manager at Michelin North America.

http://www.overdriveonline.com/match...ssure-to-load/
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(Article) BULK TRANSPORTER NEWS 9/2008

"Five tips to control your tire costs and improve vehicle performance, safety

With tires ranked as the second highest operating cost after fuel, a solid tire maintenance program can help reap solid dividends. Knowing the proper inflation level for your truck tires is crucial. TMC Recommended Practice (RP) 235 states the following determines the correct air pressure for a given load:

• Tire size and load rating
• Weight carried on each axle
• Number of tires on each axle
• Maximum speed the vehicle travels during its operation

http://bulktransporter.com/fleet/tru..._control_0908/

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(Website) [SIZE="2"]Barry's Tire Tech[/SIZE]

. . I hope you noticed how flat the wear index is for the radial tire. I interpret this to mean that conducting a "chalk test" is not a good way to determine what the best pressure is for wear.


http://www.barrystiretech.com/sae800087synopsis.html


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(.pdf) FIRESTONE MEDIUM & LIGHT TRUCK DATA BOOK

(see pages 52 for truck fuel economy discussion; and page 64 (+/-) for load /pressure tables.)

http://www.trucktires.com/firestone/...ckDataBook.pdf


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