MPG difference- TT Vs 5er of same weight?

The friendliest place on the web for anyone with an RV or an interest in RVing!
If you have answers, please help by responding to the unanswered posts.

Gary RV_Wizard

Site Team
Joined
Feb 2, 2005
Posts
77,155
Location
West Palm Beach, FL
Right, weight is not a significant factor unless all your travel is uphill. :p A lot more weight means larger tires and thus more rolling resistance, but saving a few hundred lbs isn't worth the effort.

Drag, however, is a major factor and wider or taller rigs always have more. Deflectors can help, but the right type, position & angle is often not intuitive. Plus it's not just frontal resistance - other [sometimes large] contributors include:
  • Rear suction, which literally pulls back on the rig
  • Turbulent flow over the roof due to a/c, vents, antennas, etc.
  • Turbulent flow underneath (no RV is a ground hugger)
 

MoInEd

Well-known member
Joined
May 27, 2020
Posts
115
Location
Edmonton, AB
Right, weight is not a significant factor unless all your travel is uphill. :p A lot more weight means larger tires and thus more rolling resistance, but saving a few hundred lbs isn't worth the effort.

Drag, however, is a major factor and wider or taller rigs always have more. Deflectors can help, but the right type, position & angle is often not intuitive. Plus it's not just frontal resistance - other [sometimes large] contributors include:
  • Rear suction, which literally pulls back on the rig
  • Turbulent flow over the roof due to a/c, vents, antennas, etc.
  • Turbulent flow underneath (no RV is a ground hugger)
You can try to reduce the weight (and be mindful of what you buy and what you pack). As for up/down-hill that's not in your control. The factors you mentioned all matter too, plus the driver behavior (speed, acceleration, braking, etc). I have found that the difference between going 100kph vs 110kph can be about 10% more fuel consumption. So I go a bit slower. Try to minimize use of brakes and keep rpm as low as possible. These are help.
 

Gary RV_Wizard

Site Team
Joined
Feb 2, 2005
Posts
77,155
Location
West Palm Beach, FL
Good point - high speed is one of the biggest factors and one the driver can control. Limiting your max speed can easily increase Mpg by 10%-15%. What the driver cannot always do, though, is manage speed to avoid stop & go or frequent acceleration/deceleration. Traffic sometimes takes much choice out of your hands.
 

steveblonde

Well-known member
Joined
Jan 8, 2015
Posts
4,599
Location
calgary alberta
Truck shells do not weight 600 or much less 700 lbs. Mine weights ~ 170 lbs (short bed Pickup).
Common sense says that a pickup truck with a shell towing a TT that is 8 ft wide and typical height, has less frontal area than the same pickup towing a 8 ft wide 5th wheel.

Science says that drag is directly proportional to the cross sectional area being towed. All other things being equal, the RV with the smallest cross sectional area will consume less energy to overcome the drag.

Only thing we can't really know, is the drag coefficient of the TT vs the 5fer. Those numbers are usualy measured in wind tunnels. This coefficient is also directly proportional to drag of area being towed. I would argue that the drag coefficients for the TT and 5fer are close and contribute much less to drag than the difference in cross section.
When i said 700lbs i meant the canopy 6 wake boards, 4 surf boards, all in individual bags - ropes, jackets, several tubes etc etc, sorry if i wasnt clear.
 
Last edited:

CrosbyDave

Member
Joined
Jun 25, 2022
Posts
18
Location
Crosby Texas
Update- My rentals through RV share didn't pan out. The first one cancelled on me but I never received notice until I logged back into RV share (2 days before trip) to make sure I had the paperwork I needed. The second never got back to me after I thought I booked it. A learning curve with that platform I now understand better (message owners prior to booking to make sure it's a go).

So plan...... didn't really want to but did.....went into effect.

We borrowed a friends 30' bumper pull and sway control hitch and hauled it on a 200 mile round trip.

I have my answer.
With the hitch set up somewhat proper I really didn't feel anything that screamed my 5th wheel pulled better. I could tell it was back there as I could with the 5er, but no stark differences.
Parking- I was able to stab it next to the house on my storage area slab with no issues.

My truck (2019 F-250 diesel) at 65 mph was holding 11mpg compared to the slightly heavier 5ers ~9.5-10 mpg. Not a big enough gain or loss to sway our decision.

So the answer for us = either will do.
Centering our attention towards ~32' bumper pulls that suit our desires.

Sniffing on some bumper pull toy haulers to open up our options on where we go and what we do when we get there.

And Once again, thanks for the replies, definitely provided some food for thought.
 
Last edited:

steveblonde

Well-known member
Joined
Jan 8, 2015
Posts
4,599
Location
calgary alberta
I have a Silverado 1500 with a 5.3 gas and pull a 28ft toy hauler. I average 10-11mpg. But, I do try to keep it under 65. If I run 70, I lose about 2mpg.
There is a huge difference in toy haulers from tin walls to triple axle 5ers . 5000lb to 20000lbs
 

Cameodon

Well-known member
Joined
Jul 2, 2021
Posts
357
Location
Edgewater, fl
Didn’t read this entire thread but Itowed our 33’ TT empty weighing approx 6500 - 7000lbs several hundred miles to trade for new 36’ 5th wheel (I assume that’s what some call a 5er?). 5th wheel weighed approx 10,000 lbs. maybe it was the direction of the wind whatever. Had load leveler hitch on TT. Noticeable sway even with 3/4 ton truck towing TT, none on 5th wheel.
I know I’ll be chastised for saying it but fuel mileage was as good and sometimes better hauling 5th wheel with same truck. Why? While the 5th wheel is at lease a ft taller and way heavier, it also is much more aero. Plus the 5th wheel nose is approx 4-5’ behind the cab. TT was close to 10’ behind cab. Think air current, with TT the air goes over cab, has 10’ to drop and smack that trailer like a wall where as in 4’ the air flows over the 5th wheel. You might say the 5th wheel is drafting the truck.
 

gwinger

Well-known member
Joined
Nov 6, 2018
Posts
283
Location
Natrona Hts PA
There is a huge difference in toy haulers from tin walls to triple axle 5ers . 5000lb to 20000lbs
Mine is a lightweight. GVWR, 8800lbs. Probably no where near that even with the bike in it. Would never think about hauling anything heavier with my 1/2 ton even though it's rated for 9800lbs and 1000/12009(WDH) tongue weight.
 

richclover

Well-known member
Joined
Jan 26, 2019
Posts
328
Location
WY
Mine is a lightweight. GVWR, 8800lbs. Probably no where near that even with the bike in it. Would never think about hauling anything heavier with my 1/2 ton even though it's rated for 9800lbs and 1000/12009(WDH) tongue weight.
There’s only one sure way to know what the rig weighs. Load it all (truck and trailer), for a trip. Full fuel and whatever else you want to take. Weigh the truck separately, unhooked, Cat scale at Flying J or similar. Then do the trailer, unhooked. Then hook ‘em up and weigh together. It can be “surprising”.
 

steveblonde

Well-known member
Joined
Jan 8, 2015
Posts
4,599
Location
calgary alberta
Mine is a lightweight. GVWR, 8800lbs. Probably no where near that even with the bike in it. Would never think about hauling anything heavier with my 1/2 ton even though it's rated for 9800lbs and 1000/12009(WDH) tongue weight.
8800lb gvwr x 15% tongue weight would be 1320lbs tongue weight on a 1000lb capacity
 

steveblonde

Well-known member
Joined
Jan 8, 2015
Posts
4,599
Location
calgary alberta
Yeah, but with WD he could go up to 13.5% tongue weight (13.5% x 8800 = 1188 lbs) and that is well within a typical tongue weight range. As others have said, the way to know for sure is to weigh it.
There are more variables as well like load in the truck bed etc - so its just a rough estimate my tool box in the box of my truck is a couple hundred pounds of crap im sure lol
 

Members online

Forum statistics

Threads
125,551
Posts
1,281,389
Members
131,687
Latest member
hurthunter
Top Bottom