towing milage

[alex]

i am about replacing my 28ft airstream with either 38ft fifthwheel desert fox toyhauler which weighs 11,500. i have a 2006 2500hd d/a. my other option is a 30ft bumper pull which weighs about 7500. any experienced guesses as to what the extra 4000lbs will do to fuel mileage? i would get around 12-13 with the 6500 lb airstream with cruise at 65.
thanks
alex

[DmaxMaverick]

Much depends on how you drive. More weight and a higher profile will decrease your mileage. I get 11+ towing 13K at 12.5' high. But, I drive very conservatively. If no mountains are involved (other than leaving/returning to my home), I can get 13+. You can do well, but you may have to adjust your driving habits.

[alex]

i would be very happy with that. last year i traveled alot and didnt mind paying more to get there faster. playing with the trip computer i would set it at 80 on the interstse for 10-15 miles and get around 8 and at 70 and get 10-11 and around 60 could get 14+. big penalty for keeping it at speed. i will certainly keep speeds down to keep milage high. is your truck modified? those are pretty good figures. what sort of hiway speed to you travel. it sounds like your trailer is similar in height and weight to what i am getting so it could be a good basis for comparison

[DmaxMaverick]

Intake (AFE2 with Amsoil dry long cone), exhaust, gages, boost valve, Predator, airbags, Mega filter, and probably some other things I'm leaving out. I can get better mileage, but a teenage foot on a middle-aged body skews my average. Yours, being a 2006, will be different. Adding power will help mileage (if you don't use it), because it lets you get into higher gears sooner. I've gotten as high as 15 towing, but that's on a long trip keeping near 55 in OD. I usually travel at 59-61, which keeps my average respectable. There's almost no trips I take that don't involve several mountain grades. Never underestimate the disadvantage of wind drag. Faster speeds kill mileage very quickly, as you've seen. Moreso than hills. 58 MPH (~1600 rpms) yields me the best mileage. I am never in a hurry (well....almost never). If I'm camping with others, I usually leave earlier. Once in a while, I'll treat myself to a tank of fuel for fun, and totally screw up my average. It's just too much fun not too. Something about seeing Dodge and Ford grills in the mirror.

[alex]

i may see 12-13k in the 5th wheel, should be fine for my srw. i see thats what you are driving hauling that much. are the air bags advised?

[DmaxMaverick]

Advised, but not required. I towed a couple years before installing them. Night and day difference. Toy haulers tend to have a heavier pin weight. My RV is very heavy on the pin, compared to others. I also use 285/75/16 tires, so I have a bit more cushion when it comes to weight capacity (300# more each, over OEM). The equipment is fine and performs exceptional. Problem is the legalities. Mine's over a bit when loaded up for a trip, but not enough to cause alarm. I do have to be very careful how I load it, though. Airbags help in that regard, as well. Not only does it look less loaded, a little of the weight gets transfered forward with the truck sitting level, compared to before the airbags. Tows beautifully, and I've had it in every imaginable situation. Before the airbags, I was considering a rear sway bar. After the airbags, no need. The sway bar would have cost nearly as much as the airbags, and they're not adjustable.

BTW.....
That 38' Desert Fox will put you way over your legal weight. Unless you don't put anything in it. I wouldn't do it with stock size tires. Don't believe the stickers. Or the salesman.

[alex]

that has been a concern. from chevy i see my truck is rated at 13k with a fifth wheel. the trailer is 11,428 gross dry weight. with 118 gallons water thats another 900 or so lbs, leaving me 700lbs for other cargo. i do not foresee exceeding that. are my figures correct? i seem to have the same truck as you more or less and you are pulling at least that much with no issue.

[alex]

i am running michelin ltx m/s 265

[DmaxMaverick]

The 265's are fine, as long as they are 10 ply rated (E).

You're looking at a toy hauler. If I'm reading you right, you'll have 700# remaining, after water, for cargo, including your truck loading. You WILL exceed that by at least 3X. By the time you get your "toys" in, you will need riding equipment, gas, and tools, just for the toys. For the "living" part, you will need bedding, bathroom/toilet articles, kitchen/cooking utilities, clothing, and (not the least of which), food. All this doesn't include the "normal" camping stuff, like propane, chairs, table, rugs, etc, etc, etc. Also, the "sticker" weight declaration on the trailer won't include some, if not many, options installed on the trailer. It is possible, as I've seen, the trailer will be near the GVWR before you put a can of Spam in the pantry.

All that said, I know many folks, some I camp with regularly, with rigs as heavy, and heavier, as the one you are considering. Most of them tow with 2500HD's, not unlike mine and yours. A few have some upgrades similar to mine, others completely stock. The trucks have never been a problem in the least. The chassis, powertrain, and axles are the same between the 2500HD and 3500. All the parts that count are the same, with the exception of rear springs and dual wheels. More issues come up with unloaded toy haulers than loaded. When unloaded, there's no ballast behind the rear axles to relieve pin weight. The truck/trailer combo is lighter, but more weight is carried by the truck. Not a real big deal, but it can make a huge difference when you get off the pavement, good and bad. If you've done any amount of trailering/camping, you know even the best laid plan can take a hard left turn along the way.

[alex]

i do have the e rated tires
sounds like i will be a little over rating.
thanks for the feedback. have some decisions to make

[DmaxMaverick]

I really hate to be the bringer of bad news, but that's just the way it is. Too often, dealers let folks drive off in very unsafe combinations. Their bottom line is sales. Then, there's the folks who just hook up and go, without any regard for safety, or legalities. Good luck with your hunt. We'll be here to help you do it right, if we can.

[alex]

picked up a 28ft desert fox instead. brought it home today and will leave for colorado tomorrow for a week or so.
hard to pass up the screaming deal on the 07 38fter but i didnt want to have to get another truck for it.