Tonneau or not tonneau?

[soulman]

Good evening all,

I've been"lurking" for a while now....I read a gazillion posts.....done many searches and now have a question.
First, I have a 2005 Dodge 2500 QC 4x4 SB auto with 285/70-17's. I love my truck and bought it to pull our present camper and our next one, as well. I have no idea what the rear end is (3.73/4.10?) and don't know how to find out.
Having had the truck for just a month, I've only had 3 fill-ups at 3 different vendors.
I'm not too unhappy with the mileage but would like to improve it. I've gotten 19.7 (son fill-up so not sure), 15.1 and 18.77 today. Mostly combination of hwy/city.
My son (at UNOH studying to be a diesel mechanic) said I have an MBRP 4" exhaust and a k/n air filter. I've added an Edge Mileage Max and a block heater cord.
QUESTION: I've been thinking about putting on a tonneau cover. It seems the camp is divided on whether it helps mileage. Do I buy one or save my money?

Thanks,
John

[Duffman]

They are typically worth about 1 MPG, also a good investment to protect cargo. I wouldnt have a truck without one.

[larrybuck]

I don't know what the T covers go for these days, but it would seem to me that the cover would help a little, but not a lot.
Is maybe only a 1-2mpg difference worth it to you $ wise?

Naturally, a custom fastback car look would be the most effective, but would you be able to build it yourself, and how much do you run this rig in your EVERYDAY life?

Many variables!

[soulman]

Well, I can get a Lund for $168 shipped. I think it would look good, protect stuff in the bed, but I'd like even a 1-2 mpg increase. But I also have trouble spending money, at least frivolously. I understand the ROI might be long in coming. Plus, it's getting closer to MC season.

[soulman]

Larrybuck,
Just reread your post.....I could easily build the fastback but.......I am married to the "fun-squasher" who would think "it looks stupid". I drive it whenever I can't ride my motorcycles.

[Sven7]

Buy a sheet of plywood and attach it over the rear of the bed. Bam, $15 tonneau! If the fun squasher has a problem with that, paint it black.

Even cover the back third of the bed will give you improvements and a sheet of plywood is easier to swallow than a full tonneau.

[Big Dave]

My advice is to do the tonneau. My tonneau gained me 1.5 MPG over and open bed.

Whether you go hard or soft depends on how often you need to pull it off to carry a big bed load.

[Sven7]

Phil (aerohead) says a GM land speed racer pickup used a half-tonneau for a 200+mph run. A half tonneau, not a full one. Food for thought?

AUTOWEEK carried an article for a Gale Banks GMC LSR pickup which sported the 1/2-tonneau for it's 211-mph run at Bonneville.

If this isn't it, the thing uses the same principle.


Here's the Banks Sidewinder. Notice the half tonneau.


What I'm trying to say is, although it may defy logic a half tonneau seems to work better than a full one.

[Diesel_Dave]

I've heard discussion over how much it helps, but I don't think I've heard of anyone advocating an open bed over a tonneau. I made my tonneau for about $15--leftover plywood and some high-gloss exterior enamel and you're all set. Not quite as pretty as a commerial one, but I'm cheap.

As far as the gear ratio, there are a couple ways to figure it out. Some trucks have it on a tag inside the glove department. Another option is to give your VIN number to a Dodge dealer and they should be able to tell you. You can also jack up the rear end, rotate the rear axle by hand, and count revolutions. The last option is to look up your transmission gear ratios, and tire revs/mile, then do the math between mph & rpms.

[soulman]

Thanks for all the great insight! I do appreciate the comments. But, as cheap as I am, I've decided to go with the "store-bought" tonneau cover. I found one with a good price plus an online coupon to save even more.
Thanks, Diesel_Dave for the info on the rear end...knowing that will help.