[joe24658]

New as a member of the site. I have read many of the posts over the years, but just signed up after reading the comments in this post.

I've been an Owner operator truck Driver the last 15 years. As you can imagine Fuel mileage really affected my profitability as a trucker. Also I am always looking at cost/benefits ratios in making upgrades.

One of the big components of fuel mileage is rolling resistance of the tires. In the trucking industry each individual tire is tested and given a number with respect to rolling resistance. Typically the ribbed tires are better than the drive/traction tires. Recently many have been replacing the dual setups with extra wide singles as they typically have better rolling resistance. Regardless of the type of tire, you must know the rolling resistance, as not all tires follow the typical rules. Michelin tires has a good chart for truck tires rolling resistance.

The components which determine rolling resistance are weight, tread design, rubber compounds and sidewall flexing.

In this post one person stated that he wanted to go to a heavy duty van tire so he could run higher tire pressures. While I understand his reasoning, I have to wonder how much more the van tires weigh and what their rolling resistance is.

When I bought tires for my car, I tried to find out as much information as possible. Consumer reports had a very limited chart regarding rolling resistance and this helped me make my decision. I have to wonder if there is information available for RV tires.

I also wonder how much swapping from rear duals to a wide single would help mileage. There would be less weight and two less sidewalls to flex.

Anyway. I won't run on forever on tires. I realize this is an old thread already.

Think Vortex generators (Google Airtabs). I had them on my truck and they do work. They are a lot cheaper and lighter than a boat tail and will help MPG and stability. Also you can do a lot more with them than just place them on the rear of the unit. I am amazed I haven't really heard about them more on this site. I also strategically placed some of them ahead of my doors, so that they would improve the airflow as the truck become wider behind the door. The Toyota motor home would probably benefit from this placement as well.

Last but not least there are alternatives to the big A/C unit on the roof. Call me crazy, but installing a home window unit gives you a lot more options on power consumption and therefore generator consumption and choice. At the same time, you'll get the unit out of the air.

It all depends on how you plan to use the RV and how often you run the A/C. You could find a way to mount the unit in the rear wall. (Yes think outside the box). In my truck, when I needed A/C to sleep, I would put the air conditioner through my passenger window (on the door) and close off the gap. It saved me a lot of fuel, because I was running it off a Honda EU2000 generator. I had planned to one day mount it in the rear wall.

The roof top A/C unit is typically 13K BTU. window units are as low as 5000 BTU, 6500 BTU, 8000 BTU.. you name it and up and up and up.

I can give more details on any of the above if anyone wants.

I was obsessive with MPG on my truck and am considering getting an RV and trying the same. The Lesharo would probably be the best starting point, but from what I've read it wouldn't make much sense unless you replaced the drive train.

Years ago I had a Toyota Dolphin and may get a similar unit. I think 20 MPG would be an attainable starting goal.