Tire Pressures

[photowrite]

Actually they don't. There is a reason that tire manufacturers create and publish load and inflation tables. Tire manufacturers want you running the proper pressure for the load, not max sidewall pressure for any load. Over-inflated is bad for traction, tread life, and increases the chance tire failure due to road hazards.

Agreed! Wish we could return to less litigious times and (un)common sense.

 

[Sierra1]

The lower pressure for the front tires is likely to reduce the likeliness of the ball joints falling apart from the front tires being too hard at 80 psi. I had two sets of them replaced on my 2003 before the thing was out of 3/36k warranty. The dealer told me that the reason why they were failing was due to me running the 10 ply E rating tires at 80 psi cold.

 

[Cummins12V98]

The lower pressure for the front tires is likely to reduce the likeliness of the ball joints falling apart from the front tires being too hard at 80 psi. I had two sets of them replaced on my 2003 before the thing was out of 3/36k warranty. The dealer told me that the reason why they were failing was due to me running the 10 ply E rating tires at 80 psi cold.

That my friend is a crock of Barbara Streisand! The ball joints were just junk!

 

[AH64ID]

The lower pressure for the front tires is likely to reduce the likeliness of the ball joints falling apart from the front tires being too hard at 80 psi. I had two sets of them replaced on my 2003 before the thing was out of 3/36k warranty. The dealer told me that the reason why they were failing was due to me running the 10 ply E rating tires at 80 psi cold.

Overinflation is hard on components but the lower pressures are for the lower loads.... not that ball joints.

 

[Newsa]

We're supposed to lube something up front there other than the front drive shaft. Is that the ball joints? I couldn't find anything to lube , so I'll just replace them when they go bad. Can't imagine Ram recommending a tire pressure that would destroy the front end.

 

[AH64ID]

We're supposed to lube something up front there other than the front drive shaft. Is that the ball joints? I couldn't find anything to lube , so I'll just replace them when they go bad. Can't imagine Ram recommending a tire pressure that would destroy the front end.

In the above post he said he was running 80 psi up front which is above the max recommended or needed.

 

[Sierra1]

In the above post he said he was running 80 psi up front which is above the max recommended or needed.

10 ply E load rating tires call for 80 psi for max load capacity.....

 

[AH64ID]

10 ply E load rating tires call for 80 psi for max load capacity.....

Yes they do; however, should not be anywhere near max load on the front axle, hence the reason that 80 psi is over-inflated for the front axle. A 2003 only has a 5200lb front axle and even the smallest/lowest rated OEM tires did not need to be at 80 psi for 5200lbs.

 

[kthaxton]

10 ply E load rating tires call for 80 psi for max load capacity.....

"max load capacity" being the important part of the statement. Typically, we are not driving around with a maximum load.....especially up front.

 

[TCollier]

Does anyone have an inflation chart for the Nexens? I've did some searching and can't find or have overlooked it.
I'll be hooking up to the 5th wheel for the first time with the new truck this Friday or Saturday. It'll have a pin weight of around 2400# with minimal cargo in the bed and about 1150# more for me, the family and fuel. So I'm expecting a total payload about a total of 3500#

 

[gsbrockman]

Err on the cautious side and run 80 psi fronts and 65 psi x4 on the rears.

 

[Mingoglia]

Err on the cautious side and run 80 psi fronts and 65 psi x4 on the rears.

I keep my dually at this at all times. The front of these trucks are heavy, so max pressure in the front is given. As for the back, 65 gives a good enough ride, likely enough tread life, and is still enough pressure to load the duallies up. As for the single wheel trucks, you guys are screwed. You have to adjust you pressure to the load in the back.

 

[Cummins12V98]

55 in the rear is plenty with that load.

 

[TCollier]

Thanks all. I appreciate the advice. They had 75 all the way around on my drive home from the dealer. It seemed too hard. Dropped the rears to 55 the next day trying to find a good light load pressure. Half my miles will be towing until the kids are back in school so I'll be setting everything for that until then.

 

[MichaelOverfield]

Based upon my experience, and research.. I say go with the TIRE max inflation pressure. Yes, OEMs go below these pressures, but for improved ride quality (because they can..). They want the tire to absorb some of the road imperfections for an improve smooth ride, but you pay a heavy price for this. Your tires will wear faster at a lower than full inflation, your fuel economy takes a hit, a more full tire has less rolling resistance, and builds up less heat when on the highway.. Heat kills tires, and rolling resistance kills fuel. I run full tire inflation on my cars, and truck, never had problems with suspension parts, or U-joints.. the impact goes to the springs, via the wheel bearings.. U-joints should not be affected one way or another.. proper alignment and balance are also important.

The only time I've found an advantage to lower inflation pressures is off-road where it helps for traction in soft sand and such (makes for a larger ground contact area, thus lower PSI for that area, and less sinking in the mud/sand. On the paved roads.. not an issue.

I'd recommend the tire's listed pressure be your guide (ignore the sticker!).. I'd love to hear feedback on this recommendation!

 

[kthaxton]

With full inflation, you tend to wear out the center of the tread.....and you have less rubber on the road which is bad for traction.

Every vehicle and tire combination has its own ideal tire pressure, and for a truck that is designed and equipped to carry a lot of weight, that ideal is never the max inflation pressure (when not fully loaded).

 

[Ram4Sam]

With full inflation, you tend to wear out the center of the tread.....and you have less rubber on the road which is bad for traction.

Every vehicle and tire combination has its own ideal tire pressure, and for a truck that is designed and equipped to carry a lot of weight, that ideal is never the max inflation pressure (when not fully loaded).

^^^^^What he said......Eighty pounds in a empty truck just makes for a horrible ride and beats up the equipment.......no thanks.

Sam

 

[MichaelOverfield]

kthaxton, Ram4Sam,

I've heard that argument about wear on tires, but with more miles than I can add over many years, many tires, many cars, always using tire max pressure, NEVER, not once have I seen a center wear patter on a tire.. current truck has just shy of 30K on the OEM Michellin's been at 80 PSI the whole time, no uneven wear at center there either, none on my car (which has 10 year old tires that are near end of life, but has EVEN wear, that one is a 51psi tire, and the load capacity of the tires is about 4x the car's loaded weight.

My point is I'm not buying it, experience has proven it to be false. OVER pressure will get you center wear as you indicated, not the tire rated pressure, but I've not run over pressure tires to verify that in experience.

On another thread I'm doing an analysis of ST vs. LT tires, and P tires.. there I'm finding many myths as well that just don't hold up to scientific analysis.. just because many say it and believe it, does not mean it to be true.. in that case the argument for ST tires only on a trailer, I'm finding no basis for that line of thinking..

https://www.turbodieselregister.com/threads/252125-Change-wheel-size-for-better-tires

One has to remember the OEM is conflicted on what they specify.. if the go with full tire pressure, they will have customer complaints about ride quality, and that is what is driving them, they are not worried about tire life (outside warranty anyways) and not worried about fuel economy per se.. so no reason for them to use full tire pressure, but many to use lower pressure based upon TYPICAL driving patterns. OEMs go to extensive study for how vehicles are actually used/loaded, and base many things off those patterns. You will find that if you are less than tire pressure, your tires' rated load is also less than the labeled capacity as well.. and by how much? You'd have to calculate that.. who does this? We can assume the OEM did, and those label pressures are good up to RATED load, but not an once over... Remember, smooth ride is their bigger concern.. do you think they want customers complaining about the rough ride? Ironically its a TRUCK.. somehow in the modern times many expect a truck to feel, drive and perform like a car.. but is that realistic to have that expectation? I can say my 2 GM trucks came darn close in ride quality (also used max tire pressure on them too).

 

[MichaelOverfield]

Found this gem on another thread: "I'm a tire engineer, go with what is on the door jam. If the tire is the same size as what came with the vehicle, the Auto manufacturers and the tire companies spend many hours dialing that pressure in. Having a pressure lower than that recommended pressure could lead to shortened tire life and could pose a hazard. The air in the tire supports the load, so less air and the tire is working harder than it is supposed too. If you would like to have more air in there, go ahead. Usually the ride degrades badly.
The sidewall markings on the tire for inflation are tire industry standards based on size and usage. In other words they are regulations from the government for Maximum inflation and load, they are not vehicle specific."

http://autopedia.com/APBB/Forum1/HTML/000035.html

Note, his mention about degraded ride.... exactly my point.. not that it damages the tire, or the vehicle, just don't go BELOW the pressures.. wouldn't one want to favor on the high side for a buffer, even if still a bit below the tire max... I certainly find it works.

 

[seafish]

What you just said certainly applies to stock sized tires. The issue is that many of us for various reasons choose to run a larger diameter tires on otherwise modified trucks, which demands different consideration and experience to achieve even and safe tire wear. For example, I have had to tun as low as 48 psi all the way around (unloaded truck) in order to achieve even tire wear with the Toyo Open Country At 285/75/17 E that I sometimes run on my truck that weighs in at #8200.