Drafting Big Trucks While Towing

[Paul Braun]

There is a lot of information and some informal research (Mythbusters) about drafting behind large slower moving trucks. There is a gain in mileage and as you might guess it is in relationship to the distance behind the truck. At 10 feet you can gain 44% increase in mileage. I am not in the habit of following at 10 feet so a more reasonable 100 feet will result in a savings of 11%.

Unfortunately the studies have been done using automobiles, not towed fiberglass RV's. My concern is 100 feet enough when towing? At 55 mph the recommended distance would be 5.5 car lengths which translates to 2-3 seconds or on the interstate two 1/10 mile markers. These numbers double in wet conditions.

I would be curious to hear other drivers opinions and if you draft trucks.

[Donna D.]

I would be curious to hear other drivers opinions and if you draft trucks.

No, I do not. I work for a Fortune 500 trucking company. I've seen what happens when the truck/trailer combo needs to stop quickly and the vehicles following the trailer do NOT. Seeing plenty of pictures of the back of the trailer through the windshield of a car is enough for me to give any vehicle in front of me plenty of space.

[james kent]

WOW!
You're scary!
How fast is your gas-to-brake pedal reaction time?
That's like driving blindfolded behind a billboard. You can't possibly see what's comming ahead.
I get paranoid with just some idiot in a small car drafting my little Boler. If I touch my brakes too hard he'll be in the back window, lickity split. With the extra weight of a trailer behind me I actually leave MORE space between me and the vehicle ahead.
.....and I'm normally an agressive driver.

[Roy in TO]

How fast is your gas-to-brake pedal reaction time?

In the time it takes to have a sip of decaf, one can be well on their way to a decap.

Decapitation that is.

[floyd]

Some years ago,(1980) I installed a device on my 1980 Econoline called a "Compu-cruize". It measured fuel to the 100th of a gallon, running MPG, calibrated speedo, and a bunch of other FUNctions.
I was surprized to find that the most efficient draft point was at a reasonably safe distance behind a full sized semi-truck at 55MPH which was the interstate speed limit at the time.
Too close was actually worse than no draft, too far simply eliminated the effect, but just right would add a surprizing increase to the running MPG. The key ,of course, is air management, at the point of most efficiency there is a low pressure area behind the lead vehicle.
With similar vehicles like racecars the sweet spot is intense tailgating, but with the huge difference in size and shape the Semi leading the Econoline allowed for a safer distance.
There are several reasons why "drafting" is a bad practice today however. even if you leave out "following too close".
1] Today's higher speed limit changes everything.
2] There is no longer any such thing as a slower moving truck![lol] if it is "slower moving" it's probably broken.
3] Visibility is restricted when following a truck and this could be dangerous for traffic and also for seeing traffic signs [you'll miss your exit]
4] While tailgating is ill-advised for collision reasons, it is even more dangerous to follow a truck because of crap coming off of it, like tire tread, broken brake drum parts, belly spares, chain binders, or cargo. not to mention sheets of ice in the winter, or road debris kicked up by those big tires.
5] Benefiting at all from "drafting" requires attention which is better left to traffic or even scenery and isn't worth the effort or the risk.
6] With a trailer, which is pretty much "drafting" your TV anyway, the issue becomes complicated enough that it would likely result in a loss of efficiency.
7] Your rig will get filthy and chipped up by following trucks, keep an open road in front of you whenever possible.

While even geese and bicycle racers benefit from drafting there are few occasions where you could experience any real benefit from drafting while towing.

Best efficiecy and lowest fatigue comes from slowing down, relaxing, and keeping your distance from all traffic.
And , as the song "motorcycle mama" says..... "and if the squares want by, then we'll let them pass"
then you can feel like "the queen[or king] of the highway", you'll see the world from your RV.

BTW; whose driving do you trust anyway, the stranger in the truck??
While there are many great truckers with good equipment out there, there are plenty on drugs, alcohol, or tired, with broken trucks and bad attitudes.

[Paul Braun]

All good points, as a clarification I am not encouraging this practice other than how Floyd has described it. I started out trying to find if there was a "sweet spot" that is both safe and economical. Floyd, I think you have come closest to describing that there is such a place, the question is where? Short of having a mechanical device where does one find this spot?

I like that truck lane when towing, for one it is slower and another reason is cars are more alert to trucks than the back of a white fiberglass RV. They are more alert to the potential of slow moving traffic. This lane also keeps you slower, safer and getting better mileage.

Did you know some trucking companies have programmed their trucks as to their maximum speed? Most of these limits are for fuel efficencies but apparently another big factor is tires. Empty and fast moving trucks go through tires quickly.

Here are some of the carriers known speed restrictions:

Conway frieght 62
JB Hunt 68 (older number)
Swift 62
Dart Transport 62

[floyd]

All good points, as a clarification I am not encouraging this practice other than how Floyd has described it. I started out trying to find if there was a "sweet spot" that is both safe and economical. Floyd, I think you have come closest to describing that there is such a place, the question is where? Short of having a mechanical device where does one find this spot?

I like that truck lane when towing, for one it is slower and another reason is cars are more alert to trucks than the back of a white fiberglass RV. They are more alert to the potential of slow moving traffic. This lane also keeps you slower, safer and getting better mileage.

Did you know some trucking companies have programmed their trucks as to their maximum speed? Most of these limits are for fuel efficencies but apparently another big factor is tires. Empty and fast moving trucks go through tires quickly.

Here are some of the carriers known speed restrictions:

Conway frieght 62
JB Hunt 68 (older number)
Swift 62
Dart Transport 62

If you get in close momentarily with your cruise-control off, then slowly ease back, you will feel a surge and the need for less pedal pressure. That should be about where to set your distance, if it is far enough for safe following .
I will say this though.... drafting at 65MPH will usually produce less improvement than simply driving 58.
Remember this... big trucks still have brakes and if your TV is newer than 2007, the federal government outlawed effective brakes in favor of mandatory ABS.

[James V]

Most truckers do not like this because of the high accident rate (they all have CB's and will tell each other and the cops are in agreement with them on this) and they will do things to discourage you. One trucker I knew saw a dead skunk on the side of the road and made the trailer pick it up and into the car following to close. The driver in the car had to stop and loose his lunch.

[Daryl R]

I wouldn't even consider drafting behind any vehicle, case in point was Friday evening. I was passed by a Big truck and just as it passed me it either blew off a large section of its recapped tire, or it picked one up and threw it. I thought it was going to come through the windshield. I was able hammer on the brakes in time to just drive over it, I couldn't get out of the way as there was another vehicle passing at the time. I'm fine the Van is not, I'm driving a rental and consider myself very lucky, the section of tire was at least the width of my van in length

[Perry J]

In my young and crazy days I was a Sheriff's Deputy and investigated many vehicle accidents.
Drafting is a good way to ruin your day and kill you and your family.
John

[Chris Z]

I also (in my young and crazy days) remember following a truck while on my motorcycle. It was raining like crazy and I got real close and stayed dry and the truck actually pulled me. I was idling down the road at 65mph.
Makes me shudder to think about it now. I worry too much about stuff being thrown from the tires to relax.
Once, a large long pipe came off a truck in front of me and my wife while cycling. It spun around and i kept time with it. God had other plans for me.
No more.

[Bruce Thomas]

I doubt there is that much of a savings available really? 11% at 100 ft? and 44% at 10?.
So a van that gets twenty will be in the high 30's if tailgating a truck? were that the case(and it isnt) trucks could charge you for half and allow it and the gov would be happy to oblige im sure allowing tailgating in such cases.
Like mentioned above, following that close is hard to do and most people would zig when they shoulda zagged and crash anyhow.
I belive there's an effect , just i'd like to see some real figures on it ....not anything posted by the mythbusters etc.
Bruce

[Robin G]

For me even free gas mileage isn't worth it, you never know what they have to stop for.

Not exactly a horror story, but one evening driving from Denver home, I was in center lane when a car in the slow lane, way up ahead of me blew a tire, the trucker who was in the slow lane hurried to get over in front of me, to go around the car with the flat. Just as he was getting ready to jump back in the slow lane and truck ahead of us lost a mattress on the freeway, it came out, the trucker drove over top of it but when it came out from under his truck it popped up and over mine. It was one of those times you can really do nothing but hold on, if I would have had to drive over it at 75-ish who knows what would have happened. I don't follow trucks and I certainly don't meander along side of them (Pet Peeve! ) for the reason stated earlier, they lose a tire and guess what, it's smacking you.......