Cold vs. hot tire pressure

Something to think about.... insufficient air pressure in your duallys might allow the sidewalls to touch as the tire heat-up
the retention of heat can facilitate sidewall failure over time

You might not notice it in your driveway walk arounds... but you have probably noticed dually tires touching on the truck in front of you.

Be vigilant...

You'll be ok...

Reddog1 wrote:
I see frequent references to the decal on the door, for the PSI. I have not seen it posted that this applies to the specific tire listed on the door. My point is, the PSI on the door does not apply to all tires. Change the tire size and the decal probably no longer apply

Absolutely, the decal is no longer valid if the tires have not been replaced with like tires.

Last year I helped a friend look for a used truck. You would be surprised at the number of trucks with 50K+ mileage that had tires that were less rated that the OEM tires. I guess when some replace tires they tend to go cheaper, which is usually lower rated tires.

ryoung

sleepy wrote:
My truck camper is BIG, it is off the truck 3 or 4 days a year. Those 3 or 4 days are used for servicing, rotating tires, etc. I do not deflate my tires from 80 psi for the 1% of the time the camper isn't on the truck. Though mr young would seem to insist that I should, that "his" way is the only correct way.

Sleepy, why must you always reply with a snide remark that has nothing to do with the discussion.

I never insisted or even implied that you "should do it my way."

I merely stated in my orginal post that one does not need to inflate to the side wall pressure unless they are carrying the load that requires it.

Wether or not this applies in your situation I do not know. So the discussion is not about you, your rig, your driving habits, your lifestyle, etc.

I'm simply trying to debunk the myth that the pressure listed on the tires sidewall is what the tire should be inflated to.

sleepy, you can have the last say on this, but please, you don't need to make sarcastic remarks.

ryoung

I see frequent references to the decal on the door, for the PSI. I have not seen it posted that this applies to the specific tire listed on the door. My point is, the PSI on the door does not apply to all tires. Change the tire size and the decal probably no longer apply.

I too believe the psi on the tire is the maximum for the maximum load stated on the tire. Looks hard to argue, if you read what it says on the tire.

Wayne

"essentially" "essentially the same" ???? myth's ???? arrogance yes

As we can see everyones truck/truck camper tire inflation situation is differnet... how much load, how much time loaded, how much time empty, driving on the beach, etc....

My truck camper is BIG, it is off the truck 3 or 4 days a year. Those 3 or 4 days are used for servicing, rotating tires, etc. I do not deflate my tires from 80 psi for the 1% of the time the camper isn't on the truck. Though mr young would seem to insist that I should, that "his" way is the only correct way.

I get 15.1 mpg, and I'm happy with 55,000 miles on the 7 tires... I replaced them all at once with another set (all were within 1/32" of each other)... I replaced them with another set just like the originals on the truck.

I like having a seperate truck and truck camper... I can replace, upgrade, or downgrade either component as needed...(and no... I wouldn't have a MH or class C... it seems to me that every transmission shop in North America has at least one of them sitting in their parking lot.)

sleepy

CapriRacer wrote:
I think you'll find that the table is marked "Maximum Load" for a given pressure. That is not a recommendation.

I also think you'll find the vehicle manufacturer has a specification for tire pressure listed on a placard usually located on the driver's doorpost.

This is essentially what I posted. You determine the weight the tire is carrying and then look at the inflation table to see what pressure the manufacturer requires (recommends, just a choice of words), to inflate the tire.

Yes, the drivers door placard does give the required inflation pressure, but this given pressure is only valid if you carry the maximum load (RGAWR), which is also stated on the placard.

The dually in my sig has E rated tires, whic are rated at 3042 lbs at 80 psi. But the door placard gives 65 psi inflation for a maximum rear load of 9350 lbs (RGAWR).

If I stay within the weight limits why would I ever want to inflate to 80 psi in the rear tires? Even if I ignored the GVWR and loaded up to the axel rating I still would not need 80 psi.

The old myth of setting them at 80 and forgetting it, as stated many times on the forum, just doesn't make much sense to me.

ryoung

ryoung wrote:
.....The manufacturer usually gives the "recommneded" pressure in their load inflation tables......

I think you'll find that the table is marked "Maximum Load" for a given pressure. That is not a recommendation.

I also think you'll find the vehicle manufacturer has a specification for tire pressure listed on a placard usually located on the driver's doorpost.

sleepy wrote:
did you quote me or take a line out of context? No matter.

My TC is on 99% of the time... it's an 1161 with lots of mods... it really "likes" 80 psi all around...

If I had a little TC I might need to lower the psi... wouldn't need a dually either.

After 40 years of doing this I have a pretty good idea what I'm doing.

And I get very good milage on the tires, even wear all across... I do have the alignment checked anytime I see a reason to.

I quoted what you said.

"I follow the tire mfg's recommendation... and fill the tire to the max on the sidewall of the tire... the tire has less rolling resistance at 80psi than at 65 psi.. that translates into better MPG at 80 psi."

First of all, the max pressure on the sidewall is not the mfg's recommendation. It is simply a statement by the tire manufacture giving the pressure that is needed to carry the tires maximum designed load weight.

The manufacturer usually gives the "recommneded" pressure in their load inflation tables. Hence my statement that you do not need to inflate a tire to the given sidewall pressure if you are not runing at the maximum designed load weight.

You didn't specify what the total weight that you are carrying on your GMC 3500 dually, but I can surmise that you probably need the extra pressure to do so.

As to your statement "After 40 years of doing this I have a pretty good idea what I'm doing" you sound like you were offended by my post.

My intention was not to offend you and I apologize if I did. My post was just to correct the implication you made.

Surely you haven't been driving around for 40 years with all that unnecessary air pressure in your tires.:)

ryoung

ryoung wrote:

sleepy wrote:
I follow the tire mfg's recommendation... and fill the tire to the max on the sidewall of the tire... the tire has less rolling resistance at 80psi than at 65 psi.. that translates into better MPG at 80 psi

If you are not carrying a sufficient load to require the maximum sidewall pressure, then you don't need to inflate the tires to that pressure.

True the tire may have less rolling resistance, but it also will have abnormal wear. More important, safety wise, it will have less braking and traction ability as it is over inflated.

ryoung

did you quote me or take a line out of context? No matter.

My TC is on 99% of the time... it's an 1161 with lots of mods... it really "likes" 80 psi all around...

If I had a little TC I might need to lower the psi... wouldn't need a dually either.

After 40 years of doing this I have a pretty good idea what I'm doing.

And I get very good milage on the tires, even wear all across... I do have the alignment checked anytime I see a reason to.

When driving on the beach we lower the tires to 25 and 30 psi. As they warm up I can feel them spinning. Rather than adjusting the pressure, we'll stop and hang out while they cool. It takes a long time to drive 7 miles that way!