Affect of trailer weight on mileage

We went from 2400 lbs., v-nose, single axle to 3500 lbs. , flat front, tandem axle. Mileage went from 11-12 mpg to 10-11 mpg.

changed from 15 foot 2500 lbs to 26 foot 5500 lbs lost 2 mpg (10.5 to 8.5) both mileages over a number of years. same tow vehicle.

A few years ago the Caterpillar Company had an excellent document on Coach / RV performance..

Factors affecting performance / fuel mileage
Driver
Route selection
Vehicle speed
Weight
Frontal area and coefficient of drag
Grade
Climate / ambient conditions
Fuel
GVW or GCW
Idle time
Tires

For example, they say the difference between the best and worst drivers can be as much as 20%.
Vehicle speed above 55mph becomes a huge factor. The horsepower needed to overcome Air Resistance increases as a cubic function of vehicle speed.

Frontal area and shape and speed are the biggest factors. From past experience - all with the same TV on same routes and speed. TT 1, very flat front 9 MPG. TT 2, well sloped front and not as tall same weight a #1 10 MPG. Cabin cruiser boat on trailer 1000 lb. heavier than TTs, 11MPG.

rexlion wrote:
Assuming the same width and height, I would anticipate a loss of probably 1 or maybe 2 mpg overall. Not huge.

2MPG @ 10mpg is huge as a percentage. If someone spends $5k per year on fuel, that's $1000 more!

Weight is not significant fuel usage difference between any two TTs except in the mountains. It's all aerodynamics. Any any differences between them are impossible to compare by analyses. V-Nose, more sloped front, etc could be better than straight flat up/down. But no ones know until you get it behind your truck.

Wisconsin doesn't have a lot of mountains.

Grades are where weight impacts fuel mileage significantly.

The frontal area is the major fuel mileage cost.

Normal near flat land towing - you might see a 5-10% decrease in mileage (0.6-1.2 mpg) - which you can get back by changing your driving habits.

First - the trailer takes more to get rolling and up to speed. If you drive with the higher weight like you did with the lower weight - you will be pushing the pedal down more and using more fuel. Run by RPM, not speed. Yes, it will appear that you are not accelerating enough. Stay with the RPM while accelerating.

Second - what is your cruise speed. Moving from 65 to 60 as listed above can increase fuel usage by that same 5-10%.

I went from a 30 ft ball to spare tire trailer weighing 5,200 lbs loaded to a 35 ft ball to spare trailer weighing 8,400 lbs loaded - and lost only 0.2 mpg total by watching my driving habits carefully.

Think frontal area is more important, depends upon where you travel and how fast though.

I went from my old 4000# trailer to the 7500#, loaded, same truck and driver. The mileage has dropped from 12.5 to 10mpgUS.

But I think a lot of that is the increase in frontal (54 up to 64 sq ft) and side areas (24' up to 28' long).

If the frontal area is about the same, then you should expect very similar mileage numbers.

My guess 4 mpg decrease......but that's just a guess cause there are way too many unknowns to do any more than guess.

There are known knowns and then there are known unknowns and then there are the unknown knowns.

MPG are part of the unknown knowns.......until you tow and then it is part of the known unknowns cause only you known the known knows.

I went form about 4K to nearly 8K and lost 1 MPG.