The OEM tire on the Dodge Ram 2500 & 3500 has for some time been the MICHELIN ATX A/S in 265/R70-17 (Load Range E). There are testimonials all over the web on this tire lasting above 100,000 miles. I replaced the OEM tires on mine at purchase when they had 120,000 miles (and the truck had just had the first brake job).
Matching load to pressure is the key to longest life. And jacking the tire pressure up to maximum isn't the answer as that both increases the chance of punctures and irregular tread wear, and decreases braking (tire patch contact), roughens ride and worsens handling (especially when wet).
The problem has been in determining what is the exact best pressure for a given rig (respecting manufacturer numbers). On mine, a 2WD (with slightly different GVWR and tire pressure recommendations than the equivalent 4WD) is 50-psi FF & 70-psi RR for maximum loading. Solo, 50FF/50RR.
From Post #47 of this thread,
http://www.airforums.com/forums/f238...tml#post474405
I had a Solo scale reading on the rear axle of mine of:
3,580-lbs DRIVE AXLE
And a Loaded scale weight of:
4,500-lbs DRIVE AXLE
From the MICHELIN Load/Pressure Chart provided in the above link:
Solo (1,800-lbs per tire)
I need approximately 39-psi per rear tire.
Loaded (2,250-lbs per tire)
I need approximately 50-psi per rear tire.
In other words, there doesn't appear to be a need to increase tire pressure on the truck rear. A Load Range E tire has capacity to spare and the stock recommended pressure appears adequate according to the tire manufacturer AND the truck manufacturer.
Would it "hurt" to increase pressure another 5-psi? Seems it wouldn't. (And having experimented with 40-psi I find no appreciable increase in ride comfort, handling, etc.)
And, if after 1.5-hours of steady state driving there was no more than a 3-psi rise, it would seem to be as "correct" as could be hoped for. For that day . . at that same speed, etc.
As on another day, on a rough road, with a different load in truck and trailer, in hotter or colder weather, with regular stop-and-go traffic, etc, an adjustment upwards may be needed.
Pressures that are too low for optimal handling are those where sidewall flex is high, but, with this sort of tire "optimal" may not be much of a change (if, indeed, it can actually be determined). Hard to argue, then, with 2Airs idea about adding a few pounds above what is "indicated".
If I understand correctly, some of the tire pressure monitors (TRYON) have interior temperature monitors to set an alarm (don't know if there is a readout), and there are those of us already using IR temp guns to check tires, hubs & brakes on the exterior.
Seems to me that with some tools and record-keeping that one could cover a variety of scenarios and be ready to move tire pressures accordingly for that given rig.
The next question would be:
what is an ideal tire pressure gauge?
Below are some links prepped for another site with a similar ongoing discussion. These are commercial tire and consumer tire links for those with an interest in a larger context.
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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)
[Barry's Tire Tech
. . 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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