Reduce air pressure on outside dually tire.

[Grizzly]

I was told today that by reducing the outside dually air pressure by 20 lbs when empty will reduce rolling friction, thus increase fuel mileage. Also may reduce tire wear on the outside dually and have no effect on bearings. Anyone have any thoughts on this?

 

[Skydiver]

Sounds like a good plan. The slightly deflated tire will be a little smaller in diameter. It might want to roll a little slower, thus sliding a bit. If you have an infrared temp guage the outside tire will be much hotter if the above is true.



I run 10 -ply Goodyear g-90's on my rear only. I have ran all 4 rear tires @ 25 psi only when empty to provide even were. There is less than 600 lbs. on each rear.

 

[JDiehl]

I thought I read somewhere that the preasure needs to be the same on the duals or it causes one to drag and wear faster. You could just pull the inside off.

 

[Bob Cochran]

When calculating the air pressure required on mine when unloaded after weighing at the scale I should be running around 25PSI and refuse to run less than 30 and that is what I have in them, even wear. 30 lbs minus 20 means my outside is basically flat I don't flat I don't think so.

 

[MSicotte]

Two words - IN SANE. Lowering tires pressures actually increases rolling resistance because of an increased contact patch on the road. It also creates more heat from the sidewall being able to deflect more. I agree you don't need to run 80psi when empty, but keep all the tires the same and at a reasonable level. Sounds like someone wants to sell you some tires in the near future.

 

[AABEN]

Sound like some one is blowing hot air. Dually air should be the same.

HI GRZ

 

[GAmes]

That advice didn't come from the same guy who promotes acetone in the fuel did it?

 

[HBarlow]

Hey Gary, I see you're still home. I'll be at home for a few days.

 

[jelag]

Any tire dealer will tell you that higher air pressure means less rolling resistance... we keep all ours at close to max pressure based on the text on the side of the tire... .

They ride a little rougher... but MPG is what its about...

And remember that an under inflated tire will overheat... . and fail...

 

[WestTN]

That might well have been true for bias ply tires, but radials are belted and do not change size nearly as much as bias.

 

[Grizzly]

I didn't hear it from a tire salesman, I heard it from a friend, who has the same truck I do, except his is one year newer. He's been doing it and says he has noticed an increase in fuel mileage. When he tows his 5er, he keeps the same air pressure on all 4 rear tires.

 

[icman95]

Sounds fishy to me. Lower air pressure means more tire contacting the road surface, not less. This is why off roaders lower their air pressure on sand, etc- to allow better weight distribution over the sand. Besides, even the owner's manual says to not do this because it might make the dual tires rub one another while spinning. Remember the Ford Explorer rollover fun a few years ago? It was being blamed on tires failing due to underinflation. They were overheating and self destructing. I can't see why this would be a good idea.

 

[Grizzly]

There's no weight on the outer underinflated tire. All the weight is being carried by the inner tire. With no weight on it I don't see how it can build up heat. Of course if you are carrying a load, all four tires should have the same psi.



I'm not saying I totaly agree with this idea, but it's food for thought.

 

[GAmes]

There's no weight on the outer underinflated tire.

Let someone drive over your foot, I'll bet there is weight on that tire. Under inflated means heat build up. Heat ruins tires. I doubt that if there is any mileage gain, but if there is the cost of the tire will negate any fuel savings.

 

[FJfonda]

Grizzly,

Can you have the person running this configuration use an IR temp gage and post to us the tire temp difference between the under and normally inflated tires? That, and a wear indication gage, would be the only way to tell if this can be done over time ... at $150 per tire, I'm not sure the fuel saving would be worth it if a tire failed due to overheating.

 

[Grizzly]

Grizzly,

Can you have the person running this configuration use an IR temp gage and post to us the tire temp difference between the under and normally inflated tires? That, and a wear indication gage, would be the only way to tell if this can be done over time ... at $150 per tire, I'm not sure the fuel saving would be worth it if a tire failed due to overheating.

Have you ever had a tire go flat on one of the dual's? How many days until you discovered that you had a flat tire? It's happen to me at least twice and many days went by before I discovered the flat. The last time was two years ago on our last leg home from Alaska. I checked all the tires that morning, as I do every morning while towing. We had the Lance camper on the truck. While at home I discovered the flat a few days later. No telling how many miles I drove the truck with one flat dually. Nothing happened to the tire, I had it fixed and all is still well. Now, I have a IR Fluke and I check all the tires every time we stop.



I may try your suggestion with no load on the truck.

 

[FJfonda]

Have you ever had a tire go flat on one of the dual's? How many days until you discovered that you had a flat tire? It's happen to me at least twice and many days went by before I discovered the flat. The last time was two years ago on our last leg home from Alaska. I checked all the tires that morning, as I do every morning while towing. We had the Lance camper on the truck. While at home I discovered the flat a few days later. No telling how many miles I drove the truck with one flat dually. Nothing happened to the tire, I had it fixed and all is still well. Now, I have a IR Fluke and I check all the tires every time we stop.



I may try your suggestion with no load on the truck.

Never had a dually flat, but had one tire low --- all the other 3 ran 90-95 deg and the low one ran 130 deg. This was towing a trailer with 900 lb tounge wt and 800 lbs in the bed... .

Not sure what temp drives tire degradation --- I use the IR all the time for truck/trailer tires and trailer bearings. Invaluable tool.

 

[THoltz]

Check your owners manual or tire info packet. I think it would be smarter to follow the manufacturers guidelines.

 

[MMeier]

When calculating the air pressure required on mine when unloaded after weighing at the scale I should be running around 25PSI and refuse to run less than 30 and that is what I have in them, even wear. 30 lbs minus 20 means my outside is basically flat I don't flat I don't think so.

What's there to calculate???? Pressure is listed on the tire sidewall, plain and simple... 80 PSI on E LR tires

 

[HBarlow]

Never had a dually flat, but had one tire low --- all the other 3 ran 90-95 deg and the low one ran 130 deg. This was towing a trailer with 900 lb tounge wt and 800 lbs in the bed... .

Not sure what temp drives tire degradation --- I use the IR all the time for truck/trailer tires and trailer bearings. Invaluable tool.

IMO, this post probably provides the best answer to the question. Almost a scientific comparison test to determine what happens when one tire of a pair of dually tires is underinflated.