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Old 10-20-2016, 01:03 PM   #15
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Originally Posted by Jacobnino View Post
Ok oh wow thats interesting, i read that 55-60 mph is the right spot for mpg right?
Until computers became widespread in cars, the common wisdom said you got the best mileage at the slowest speed of the highest gear. For my cars, that was about 35 mph- not a practical highway speed.

If you hold to 55 mph, expect at most a few tenths of a mpg improvement over 60.
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Old 10-20-2016, 01:03 PM   #16
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1,000+ miles - 100 gal - 330hp diesel..... Sweet spot is 60-63 mph....
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Old 10-20-2016, 01:04 PM   #17
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Quote:
Originally Posted by CountryFit View Post
mine might sound too good to be true, but it is what it is, no fun for me to cook numbers! frankly speaking, mine is doing exceptionally well. don't ask me why becuz i don't know. i just recently ran a long trip with multi tanks, the result confirmed the old numbers -

total miles you get with a full tank of diesel fuel: 970
How big is your fuel tank on gallons: 100
the size of the engine: 8.3L (Cummins ISC 350)
And how big is your mh: 40ft with one slide
Average city and freeway/highways: (i assume you are asking mpg): 9-10 mpg. the latest was 9.7.

a few things i'd like to mention:
1) i only fill D2, no bio. my engine does not like it. if i see a tag on the pump saying % bio, i drive away
2) my tire pressures are in line with manufacturer's spec: front 120, rear 115 psi
3) i don't load stuff that i'll never use.
4) removed the washer/dryer, to reduce the chance of water leaking and the weight
5) replaced the flooded coach batteries with much lighter li.
6) but added the weight of solar panels.
7) towing honda fit sports (very light about 2700 lbs)

happy trails!
I wondered about your tire pressure! On my 40' Windsor, using the tire manufacturer's charts and the weight of my MH, I run 100 on the rear and 105 on the front, and that's adding 5 PSI to the manufacturers recommendation! My MH weighs about 33,000 lbs now.
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Old 10-20-2016, 01:09 PM   #18
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Originally Posted by Jacobnino View Post
Hello everyone!!!!!!


Post the avarage total miles you get with a full tank of gas
How big is your fuel tank on gallons
the size of the engine
And how big is your mh
Avarage city and freeway/highways

I have a 97 itasca 33rq with the
7.5 efi v8 ford engine
75 gallons gas tank

Next week will be my first trip so i can have an idea how many miles i can get with a full tank

Thank u!!!!!!!
I would start by using 7mpg and multiply x 75 to start with. Record starting mileage then finish mileage on your 1st fill up and figure out your mpg. Do that at every fill up and you will be able to get an idea of what your average mpg is. You can then play with that by trying different cruising speeds
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Old 10-20-2016, 01:25 PM   #19
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So avarage mpg on any class a motorhome its around 8 mpg no matter the length

total miles of a full tank all depends in how big the fuel tank is
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Old 10-20-2016, 01:35 PM   #20
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Quote:
Originally Posted by Jacobnino View Post
So avarage mpg on any class a motorhome its around 8 mpg no matter the length
total miles of a full tank all depends in how big the fuel tank is
Not quite true on the MPG. That's going to depend totally on the weight, engine, driving style and conditions. After over 30,000 miles driving a 36' Itasca with a Workhorse Chassis, the overall MPG was 6.0 towing a Jeep. On a good day with a tail wind, maybe 7.5, if going up and down hill into a head wind it was around 5MPG. I always filled at just below 1/2 tank, so we could get about 325-350 miles on a tank. With the diesel, after 11,000 miles the overall average has been around 8.5MPG. With 100 gallon tank I usually do about 400-450 miles before fillup at just below 1/2 tank.
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Old 10-20-2016, 01:52 PM   #21
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43' motorhome, 8.9L Cummins ISL
150 gallon tank... averaged 7.8 mpg on last trip of 2,497 miles.
Tire pressures are set for the weight of the rig with full fuel and fresh water tanks, towing a car and fully loaded for a long trip - 110 psi on steer axle, 100 psi on drive axle, 90 psi on TAG.

Mathematically, I can get 1,200 miles out of a tank, but of course I never let it get down that far. My gauge is also not all that accurate, so when it says I have a half a tank of fuel I actually only have about 1/3 of a tank. (I know this because at half a tank on the gauge I can squeeze in 90-100 gallons). I typically plan out fuel stops along the way for convenience and price, not for how much is left in my tank, so I almost always have more than half a tank of fuel on board.

I typically drive 65-ish mph except in California where I drive right around 60 because of the towing / 3-axle speed restriction. I don't care about an extra fraction of a percent of fuel mileage, I drive to match the conditions of the road and traffic. On most highways / freeways 65 works out very well... traffic can still go around me if they want, but I'm not coasting along like a rolling road block either.

That said, I have to admit that on our last leg home in Nevada the speed limit was 70, and because 1) I was alone on the rig, 2) I wasn't towing our car and 3) all the wet tanks were basically empty, I set the cruise control to 75 and sailed home. Handled like a dream and the fuel mileage only went down about .4 gpm (it was ridiculously windy that day). That .4 would make a significant difference on a long drive cross country, but I was only about 150 miles from home so it didn't even make a dent.
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Old 10-20-2016, 01:54 PM   #22
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VMSpc says lifetime mileage is 7.3 with 70718 on the clock.

Of course from the PNW to the RGV is uphill both ways and the wind always blows in my face!

My TOADs are heavy, a Honda Odyssey and Ford Flex. The DW does not pack light! lol

Most miles traveled without fill up 638. Usually stop once everyday for fuel.


Scott: If I milk it, I can add ~ 15 gals after the auto shut off, then the Gage reads full.
FL did a poor job on the venting.
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Old 10-20-2016, 03:16 PM   #23
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Originally Posted by MSHappyCampers View Post
I wondered about your tire pressure! On my 40' Windsor, using the tire manufacturer's charts and the weight of my MH, I run 100 on the rear and 105 on the front, and that's adding 5 PSI to the manufacturers recommendation! My MH weighs about 33,000 lbs now.
good catch joe . i was doing that based the following facts:

1) on the wall under the window next to the driver seat, a chart specifies front 120 psi and rear 110 psi. considering heavy load when water is full right at the front of the rear axle, i added 5lbs to make it 115 psi.

2) on the tire sumitomo 12r22.5 side wall, there is wording "max load 7390 lbs (120 psi)". i understand it really means to carry max 7390 lbs you need to retain min 120 psi.

3) most of blowouts are caused by under inflation. on each wheel turn, the side walls of the tire experience bending/flexing/restoring. the lower the pressure the severe that is. over time, the fatigue will make the tire belt/liner/carcass separate hence blow.

4) sure the lower psi makes ride smoother. on the other hand, the higher psi gets a better fuel mileage. thus it is a compromise to choose a psi.

5) i compared the pressure at 100, 110 and 120 psi in front. the lower the smoother in riding, however, 120 is not that bad. rear pressure has a marginal impact on the feeling.

overall, i have been running on these psi's for past few years. my previous set of bf goodrich was replaced after 8 years with very minor side wall hair lines. the current set of sumitomo was installed 15 months ago. i am happy for the fuel mileage and no complaints for the riding .
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Old 10-20-2016, 03:34 PM   #24
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Quote:
Originally Posted by Jacobnino View Post
Hello everyone!!!!!!


Post the avarage total miles you get with a full tank of gas
How big is your fuel tank on gallons
the size of the engine
And how big is your mh
Avarage city and freeway/highways

I have a 97 itasca 33rq with the
7.5 efi v8 ford engine
75 gallons gas tank

Next week will be my first trip so i can have an idea how many miles i can get with a full tank

Thank u!!!!!!!
1200-1500 miles per tank
150 gallons
6v92 Detroit
40 foot
8.5-10 miles per galon
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Old 10-20-2016, 03:45 PM   #25
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100 gal diesel
10.5-11.5 mpg
1000+ miles range
isb 340 hp

Typically fill up before reaching 1/4 tank, depending more on where the best prices are along the route (thank you Gas Buddy). Some states fuel taxes are worse than others.
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Old 10-20-2016, 03:48 PM   #26
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38' Gas
75 gal tank
Always fill up before 1/4 tank, so generally go 450-500 miles between fill up.

And I agree with the statement above. I get about 8.5mpg at 60mph, but it drops to 7.5mph at 65mph
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Old 10-20-2016, 04:14 PM   #27
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Quote:
Originally Posted by CountryFit View Post
good catch joe . i was doing that based the following facts:

1) on the wall under the window next to the driver seat, a chart specifies front 120 psi and rear 110 psi. considering heavy load when water is full right at the front of the rear axle, i added 5lbs to make it 115 psi.

2) on the tire sumitomo 12r22.5 side wall, there is wording "max load 7390 lbs (120 psi)". i understand it really means to carry max 7390 lbs you need to retain min 120 psi.

3) most of blowouts are caused by under inflation. on each wheel turn, the side walls of the tire experience bending/flexing/restoring. the lower the pressure the severe that is. over time, the fatigue will make the tire belt/liner/carcass separate hence blow.

4) sure the lower psi makes ride smoother. on the other hand, the higher psi gets a better fuel mileage. thus it is a compromise to choose a psi.

5) i compared the pressure at 100, 110 and 120 psi in front. the lower the smoother in riding, however, 120 is not that bad. rear pressure has a marginal impact on the feeling.

overall, i have been running on these psi's for past few years. my previous set of bf goodrich was replaced after 8 years with very minor side wall hair lines. the current set of sumitomo was installed 15 months ago. i am happy for the fuel mileage and no complaints for the riding .
Yup, I can understand where you would get better fuel mileage with the higher pressures! I would be concerned that you would wear the tires more in the center than the outer edges though.

It is DEFINITELY better to run higher than recommended pressures rather than lower! That's asking for a blowout in my opinion!
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Old 10-20-2016, 05:38 PM   #28
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IMHO, in addition to mileage it is important to know how many gallons are left at 1/4 tank, or whatever gauge amount triggers the decision to start looking for fuel. Our first trip long with the MH was this Summer and there were several times when I put between 60 and 65 gallons in the 75 gallon tank with about 1/4 tank showing on the gauge. Our mpg averaged about 7.5 for the 7K mile trip at 70-75 mph one way and 65-70 coming back with the Tracker in tow. So at 1/4 tank we had between 10 and 15 gallons left, or 75 to 112.5 miles. I would be inclined to think of it as 50-75 miles in order to have a bit of a cushion. There are some places where even 112.5 miles would not be enough to get to a gas station which would then require filling before getting down to 1/4 tank, although I used 1/4 for most of the trip. There are a lot of things to consider.

Abnormal tire wear in the center would be my concern with over inflation too. I run mine where the manual indicates and hope they will last a long, long time. :-))

Best of luck with it.

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