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-   -   MPG Story and Best Tire Pressure on stock 20” Goodyears (http://www.ramforumz.com/showthread.php?t=86628)

RamboObmar 07-07-2011 11:26 PM

MPG Story and Best Tire Pressure on stock 20” Goodyears
 
Hi Guys,

My 2011 Big Horn/CC/Hemi/3.55/soft tonneau’d Ram has a little over 5,000 miles on it now.

I took the family for a little vaca over the 4th from Boston to Maine. About 240 miles each way. I travelled with my wife, 3 young kids, and a week’s worth of “stuff” filling the bed about 3/4 of the way under my tonneau. So figure about 500 pounds of people and 200 pounds in the bed.

On the way to Maine and back to Boston, my tire pressure was still where it was when I bought it in February. Each tire was at 44 PSI cold and 46 PSI when warm.

We drove in very little traffic, but in many, many (sign of the times) speed/radar traps. So I just set the CC to 68 mph and could routinely travel for 20 or more miles at a time before having to tap the brakes. On the way up, I got an on-ramp to off-ramp (rt95, about 200 miles) MPG of 20.3 on the EVIC using Boston Gas and 19.6 MPG coming home on a refill of Maine Gas (with Ethanol). The traffic density was about the same both ways, I just chock up the difference to winds, minor slow downs, etc…. or maybe it was the Ethanol in Maine’s gas?.

Anyway, I think that is excellent milage either way assuming the EVIC is close to true MPG.

My question is, do any of you guys see similar MPG under similar conditions when running the factory recommended 35 PSI ? I’m thinking not and that my good mileage, and rather rough ride, is due to the high tire pressure. That said, I would be willing to sacrifice a little MPG for a softer ride due to running the lower factory recommended 35 PSI.

All comments/experiences welcome.

Thanks, Ed

gysnst2 07-08-2011 05:50 AM

I'm actualy running mine at the tire max. I feel u get the longest tread life and the best mileage. Unless I'm off road then I'm lowering the tire pressure. With the max tire pressure. The ride of the truck is still great.

Excoastie 07-08-2011 07:28 AM

I've got an '10 CC Sport with the HEMI (3.92 rear end). I just did a 200 mile round trip to a zoo in East Tx. I was running 70-75 on I20 and I got 17.62MPG with the tires inflated to the factory 35psi (warm temp of about 38psi via EVIC). This was very hilly, so I'm sure that had something to do with the mileage. I was quite please with it though.

Last year I took a trip to New Orleans (about 350 miles one way) and I got about 20MPG going down with the cruise set at 69. Coming home I was running 75--80 and got about 17 MPG. This is mostly flat roads, so again I was quite pleased with the results.

Where in Maine did you go? I love that area up there, and miss it. I was stationed in Portsmouth, NH while in the Coast Guard and took frequent trips up along the coast when I was broke and had time on my hands (gas credit cards were wonderful things back then LOL)

Exco

racerx9987 07-08-2011 08:06 PM

Took Mine to North Carolina from pa about a 450 mile ride. Got 20.5 going there and 20.3 coming home cruise on just about the entire time except the 45 mph zones. Air conditioner on entire time and 4 passengers with bed completely loaded. I do have a tonneu cover and was running 36 psi did great i thought for all of the stuff in the back and 3.92 gears. I did the calculation rather then rely on the evic.
Nate

RamboObmar 07-08-2011 08:52 PM

Hey there - we went up to the Belgrade Lakes region about 30 miles northwest of Augusta. It is nice up there - can really escape the rat race... Portsmouth is a fun city and a great port…. tough in the winter tho.

I’m really starting to think that the 3.92 gears don’t suffer from any worse gas mileage than the 3.55…. As someone else first noted, the 3.92 gears probably allow the motor to kick into ECO mode sooner than the 3.55 gears and to stay in ECO mode longer when engaged.

Anyway, I dropped my tire pressure to 38 cold F/R and can definitely report that the ride is much much softer. I drive the same backroads to work everyday, so I know where the bumps are and I can feel the difference. Not only is the ride more smooth, there is less suspension and tire NVH. Makes sense. I’m going to try 35PSI cold F/R tomorrow to see if the ride improves further.

Thanks for the reports, Ed







Quote:

Originally Posted by Excoastie (Post 564201)
I've got an '10 CC Sport with the HEMI (3.92 rear end). I just did a 200 mile round trip to a zoo in East Tx. I was running 70-75 on I20 and I got 17.62MPG with the tires inflated to the factory 35psi (warm temp of about 38psi via EVIC). This was very hilly, so I'm sure that had something to do with the mileage. I was quite please with it though.

Last year I took a trip to New Orleans (about 350 miles one way) and I got about 20MPG going down with the cruise set at 69. Coming home I was running 75--80 and got about 17 MPG. This is mostly flat roads, so again I was quite pleased with the results.

Where in Maine did you go? I love that area up there, and miss it. I was stationed in Portsmouth, NH while in the Coast Guard and took frequent trips up along the coast when I was broke and had time on my hands (gas credit cards were wonderful things back then LOL)

Exco


erm 07-08-2011 10:00 PM

I would think that is exactly why, not to mention good conditions and lots of time at steady state cruise.

The upside to that psi is that you have less rolling resistance to deal with.

The downside is that the center of your tires may wear a bit faster than the outside, in other words, you may see some uneven wear.

ConchFritter 07-08-2011 10:27 PM

I am in the middle of a road trip from the Florida Keys to Carlisle, PA. I kept my tires the way they came at 45 psi and I have a tonneau cover with the 3.55 gears. My computer was showing 21.2 when I got here yesterday. I hand calculated the average on one tank and we got a bit over 20, after a day of hills and 70 mph driving.

I have been over-inflating my tires on all my vehicles for the past year or so, in order to cut down the rolling resistance - and like the guy at the tire store said 'how many tires have you seen worn out down the middle?'

CHVYKLR 07-08-2011 10:50 PM

700 mile round trip VA-NC-VA driving 65-68mph with my 4.10s and stock 20s I managed 21mpg when aired up to 35psi.

I routinly get 19-20 mpg driving to-from (23 miles each way) work.

bobhorn 09-29-2011 04:32 PM

Hey I know it's still young,just hit 1,100 miles but my lightweight
2wheel drive express 392 grs and 20's bearly gets 12 mpg
local and on a trip upstate all highway 70-75 14.5 mpg
I'm driving normal not beating her up? WTF? Help!

erm 09-29-2011 05:36 PM

MPG gets better with some more miles on the truck, bobhorn.


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