What is the average miles per gallon for a refrigerated tractor trailer fully loaded?

I am assuming you are looking for a tractor and trailer with the reefer unit running. Of course the temperature of the load will effect the run time of the reefer, and in turn the mpg, but a fully loaded tractor should get 6-7 mpg and a reefer unit will consume about 1 gallon per hour. As a quick number, the combo will run about 6-6.5mpg. This true to an extent, but greatly depends on many factors... 1. MilesPerGallon is also based on MilesPerHours, running 58-62 mph give optimal mpg (slow down 1-2 mph when in headwinds but run slower in hills and mountains and closer to 62 on flat). Going 65 as opposed to 62, burns more fuel and you get to destination only about 15-30 seconds sooner.

2. Knowing when to shift....Downshifting in grades helps, rather than speeding up grades and breaking in down grades. A tractor is made to work better at lower rpms during shifting. (in a 10-speed, for example, shift around 11-13 rpm.) Lug the engine, don't shift too high. Let the tractor do the work...she will pull the hills for you, then when it's permissible, flip your engine break switch and break easy down hills - slowly apply and release down hills...never ride breaks continuously. Maximum torque in a 10-speed is reached at 13 rpm, shifting higher than that wastes fuel. Best to know your truck's maximum torque at what rpm and never shift higher than that rpm. To do so is of no benefit and is just crazy.

3. Idling gives you 0 mpg. Investing in an APU or IdleAire will significantly improve your mpg. My trucks never idle, we have APU (Tripacks)

4. Load balance...balancing your load as evenly as possible between your drives and tandems. Loads especially heavy on your drives, kill fuel mileage.

5. Terrain....my trucks (Freightliner century class or cascadia) get an average of 7.0 mpg on flat and 5.5-6 in the mountains or hilly terrain.

6. Make/Model and Engine of your truck. Volvo is more expensive, but best mpg.

7. Make sure your tires properly inflated...more than 8 psi low kills fuel mileage.

8. Maintenance. If it's been more than 25,000 since last PM, count on your MPG falling. And keep and eye on fuel filters in between PMs, opt for the premium filters.

9. Fuel...some brand fuel is cleaner than other brands. Shop around and actually look at the fuel, some brands even look filthy, stay away from these guys. May cost a little more for better fuel, but burns slower and keeps you out of the shop as much, which makes your overhead cheaper.

I have to disagree about the Reefer part. Our reefer units use a separate fuel tank, so reefer, dry, tanker or flatbed shouldn't matter. I've never heard of a reefer and tractor sharing the same fuel tanks. Reefer trailers use 1/4 tank of fuel every 24 hours on continuous run. But understand a Reefer Trailer has nothing to do with your MPG whatsoever. Reefers fuel is based on time not miles.

The average truck reefer or not, should get between 6 and 7 mpg. Fully weighted (around 45,000), you should get at least 5.0 mpg in the Rocky Mountains - probably the worst terrain for fuel mileage.