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Where is the line between too small and too big?


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I've go a 23' travel trailer, bumper pull. Id love to have a bigger trailer. Sometimes I want a smaller one. But as long as you're towing a piece of plywood down the road, where is the line where you start using a lot more fuel. The wind resistance is already there. So how much bigger can I go without seeing a big jump in fuel consumption and stress on the tow vehicle? Currently 7,000# GVW.

Edited by joecool911
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Well it kinda come's down to how often you go, How far you go, and How many people want to come along. The first Pic is of my Parent's camper they bought to try out camping a few years ago It's a 2005 Starcraft Travel star 32'  about 6000pds loaded for a week long stay. Great camper but, needed some minor repairs and only cost us 3K including repairs. When i used my old Mega cab (Before it got Totaled a few years ago) man it towed so good behind my truck i never knew it was back there. I've towed it with my New to me persay 2001 dually 24 val HO 6spd same thing never know its there pulls great and the brakes on it were strong even on 3.0 they could stop my truck on a dime... Now that My Mom, dad, sister, Her husband, my self, Grandmother, and great aunt and a Blue healer mix and my Big old Bassett hound want to come we needed another camper and a bigger one at that so....Last year I scored a killer deal on this 1998 Newmar Moutain aire got it for $7,500 its a 40' footer and weights in at a Whoppin 19,000pds loaded for the same length stay. My Dually know's that baby is there it can pull it and stop it no trouble but, just don't be in a rush it'll do 75 all day down the interstate but why i'm on vaction why rush...So what is your criteria for this new camper

 

As far as MPG I get about 16 pulling my parent's camper and 13 pulling mine unless i'm showing off then it goes down more lol Cause when you see a bunch of Hot girls checking you and your truck out....yeah your gonna lug that baby a little hehe but really not a huge difference in MPG between them.

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Edited by GreenRiverCummins
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...well, since were all whipping it out and seeing whose is bigger... :tongue:

 

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I'm averaging about 10MPG pulling it. I have oversized tires, and a cracked exhaust manifold. So the mileage would probably do better if I were to remedy these. I also tried to pull it at 55mph any chance I got as it is better MPG wise and stability wise. I'm an SRW so I can't take as much weight as a DRW. Nonetheless, the pin weight can be heavy as its a toyhauler.

 

If you were to plot trailer size, weight, aerodynamic profile, you would not see a straight line, but a progressively steeper curve.

 

You have to use your judgement on what will dictate your line that you cross. You could get a really small trailer but be really heavy. You cross the line as the weight over does it and the size is no longer helping. You go with a big trailer but it is lighter. You hinder yourself now, because you are like a kite in the wind, even though its light.

 

This is for example, as we know the bigger something is going to get, trailer wise, expect it to be heavier. But I was equating this to say, a small bumper pull trailer but your pulling a 10k lb tractor. Its small, the profile is small, but the weight is not proportional to the size, so to speak. Its a juggle...

 

You have to factor in the variables like previously mentioned above and figure out what its worth to you and where to set your line. Fuel mileage is not going to be the only single determining factor.

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I can tell you Hex0rz has a huge 5th wheel. Thing is most people tend to forget about axle weight and vehicle design weight. Like Hex0rz is most likely over his rear axle weight limit (can't remember). Then most all Dodge Truck of the 2nd Gen realm are designed for about 13,400 pounds of trailer even the 1 ton's are the same weight.

 

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My setup has changed over the years from a empty bed and a 22' TT at 15K GCW to a pair of ATV's in the bed and a 30'TT at 19-20K GCW and my mileage has shifted down about 1 mpg. I was 10-12 with the 22' TT most the time and now I am 9-11 with the heavy setup.

 

There just comes a point when wind resistance overcomes weight.

 

I get slightly lower mileage with my hitch that I could. I run the 18" shank to aleviate all tailgate interference, and that added space between the truck and camper does decrease mileage. I have never tried a standard shank on this pickup, but when I switched from a standard shank to a long shank on my Toyota Tacoma with a 1200lb pop-up I lost ~1-1.5mpg's, better than 10%.. and that was a TINY popup.

 

 

Pretty darn close here... :shrug:

 

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Your GVWR isn't 13,400... it's 8,800. The labels aren't there, but it looks GVWR/Engine/Trans/Gears/GCWR/SWB max tow/LWB max tow.

 

Using your other numbers and correct GVWR your limits are 6,500/10,400 according to that page.

 

My "limits" are similar, I have a higher GCWR and GVWR but also a higher GVW.

 

I say "limits" over limits because GVWR is meaningless to me, and to any other SRW owner that really pay attention to the numbers.

 

The design weight of my frame/steering/brakes/front axle is the same as a DRW, thou some numbers are different. My rear axle is the same unit. The only difference is minor with spring rates (think airbags) and tire capacity.

 

I can load up to 12,200lbs on the truck in stock trim and only be overloaded on the rear tires, but with my 19.5's I can increase my RAWR from 6,200 to 9,000lbs which is more than I will ever need.

 

So in reality I can hit 12,800 for 5er or bumper pull...but to be honest I wouldn't hesitate going over GCWR as long as I was within front axle, rear tire, and frame (12,200) limits. I towed this weekend at my OEM GCWR and there where zero issues, I didn't run hotter than normal or have any acceleration issues. GCWR is mostly based on acceleration and cooling capacity. My cooling system is the same as a 4.10 truck with a 23K GCWR (vs my 21K) and with my extra power accelerating and maintaining speed isn't an issue, even then I am not even within 10° of the max allowed coolant temp from Cummins.

 

Okay Rant off... I just despise the way that OEM's rate their SRW vehicles. It appears that that is changing thou, a 2014 3500 SRW Ram is rated to what it should be based on components and they ditched the POS 17's for 18's on the higher RAWR trucks.

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I posted the correct numbers. 16k GCWR, 8800 GVW, 7500 scale weight, 190 driver, 300 for extra cargo (tool box with misc tools, chains, shovel, fluids) and 25 gallon aux fuel tank under my tool box. Now playing with numbers I can add/subtract 100 lbs to either the scale weight or cargo and it changes the tow ratings significantly. Strange.

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When subtracting the GVW and cargo/passenger weight from GVWR, that gives you available payload of 810 pounds. Calculating the conventional max towing capacity @12.5% TW, the max tow is 6,480 pounds.

 

8800 - 7500 - 300 - 190 = 810 available payload

 

Since the calculator uses a percentage to calculate the max tow based on available payload, the results is more affected by lighter payload capacities; even small amouts of changes in weight. The key here is to prevent a vehicle from exceeding the GVWR primarily and then GCWR second.

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The key here is to prevent a vehicle from exceeding the GVWR primarily and then GCWR second.

 

This is a good rule, but not on all vehicles. We probably don't need to make this a rv.net style discussion but GVWR is not very important on these HD trucks. FAWR is important, and RAWR is important (or tires if higher than RAWR and lower than DRW RAWR), and the combination of those will exceed all SRW GVWR's. The max GVWR for the DRW is 11,000 and that should be the max GVWR for the SRW with RAWR/tires permitting.

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When subtracting the GVW and cargo/passenger weight from GVWR, that gives you available payload of 810 pounds. Calculating the conventional max towing capacity @12.5% TW, the max tow is 6,480 pounds.

 

8800 - 7500 - 300 - 190 = 810 available payload

 

Since the calculator uses a percentage to calculate the max tow based on available payload, the results is more affected by lighter payload capacities; even small amouts of changes in weight. The key here is to prevent a vehicle from exceeding the GVWR primarily and then GCWR second.

I understand how they get the ratings, I guess what I'm saying is it's overly conservative IMO. My lower GCWR compared to other trucks of my year are due mainly to the auto trans and gearing but I don't consider the trans a factor since mine has been built to tow. In my case my tires are my crutch. My rear GAWR is 6084 which is based on OEM 245/75/16. My 285/75/17 are rated for 6400 combined, which is still under the 7500 that Dana rates the D70 at. My biggest concern when towing is that I don't exceed my tires, the rest of the truck is more than capable.

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This is a good rule, but not on all vehicles. We probably don't need to make this a rv.net style discussion but GVWR is not very important on these HD trucks. FAWR is important, and RAWR is important (or tires if higher than RAWR and lower than DRW RAWR), and the combination of those will exceed all SRW GVWR's. The max GVWR for the DRW is 11,000 and that should be the max GVWR for the SRW with RAWR/tires permitting.

 

I don't know what you mean by "rv.net style discussion." I, and all vehicle manufacturers, disagree with you. GVWR should never be exceeded on any vehicle. Every manual and website clearly states that. GVWR will be exceeded before the combined GAWR is maxed out.

 

For example, look at RAM's highest tow rated 3500 truck: (Corrected)

REGULAR CAB LONG BOX 4X2 ST / TRADESMAN DRW

Front GAWR: 5500

Rear GAWR: 9750

Total GAWR = 15,250

GVWR = 14,000

 

Here is RAM's highest tow rated 2500 truck:

REG CAB LONG BOX 4X2 ST/TRADESMAN

Front GAWR: 5500

Rear GAWR: 6000

Total GAWR = 11,500

GVWR = 10,000

 

You can select any vehicle you want. The combined GAWR will exceed the GVWR every time. Therefore, that is the reason emphasis is placed on GVWR and payload for calculating max towing capacity.

 

*The above weights came from RAM's published information.

Edited by TheTowMaster
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I understand how they get the ratings, I guess what I'm saying is it's overly conservative IMO.

 

I understand. Based on over 30,000 RV weight records from RVSEF, the national average 5th wheel pin weight is 20%. The average TW is a little over 12%. So the percentages used in the app are a very good and safe starting point when purchasing an RV. Current RVSEF data indicates that 60% of all trucks towing an RV exceed at least one rating. The goal of the app is to aid in reducing the high overweight percentage and assist buyers and dealers.

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I don't know what you mean by "rv.net style discussion." I, and all vehicle manufacturers, disagree with you. GVWR should never be exceeded on any vehicle. Every manual and website clearly states that. GVWR will be exceeded before the combined GAWR is maxed out.

 

For example, look at RAM's highest tow rated 3500 truck:

CREWCAB LONG BOX 4X4 ST / TRADESMAN DRW

Front GAWR: 6000

Rear GAWR: 9750

Total GAWR = 15,750

GVWR = 14,000

 

Here is RAM's highest tow rated 2500 truck:

REG CAB LONG BOX 4X2 ST/TRADESMAN

Front GAWR: 5500

Rear GAWR: 6000

Total GAWR = 11,500

GVWR = 10,000

 

You can select any vehicle you want. The combined GAWR will exceed the GVWR every time. Therefore, that is the reason emphasis is placed on GVWR and payload for calculating max towing capacity.

 

*The above weights came from RAM's published information.

 

 

You missed my point. GVWR is nothing but a marketing limit on HD SRW trucks, across all 3 manufacturers.

 

Look at the Ram 4x4 CC LWB GVWR's, there are several of them despite the fact they are all on the same frame/suspension/brakes/steering/etc... None of them are at a design limit.

 

GVWR is also not a legal limit, but tires are.

 

Take the badging away, take the GVWR away... and what is the difference between a 2500, a 3500 SRW, and a 3500 DRW?? Less than you think, especially in what counts.

 

In short any SRW is limited by it's tires, that's about it.

 

GVWR is not a good indicator of capability, it's an indicator of what truck was purchased. For years SRW trucks had a 9,900 GVWR only to stay under the 10,000 weigh station limits in many places. As soon as Ford (pretty sure they where first) jumped over 10K on a SRW everyone followed. Dodge didn't change a single part, except the sticker.

 

The frame in my truck is rated to 12,200 by Dodge, with a max FAWR of 5200 and RAWR of 9,350. Those are closer to the real limits. Brakes are going to be the first structural limit, and why I personally use 12,200 as a max.

 

It's only in the pickup world where FAWR+RAWR < GVWR, it's mostly marketing math.

 

The only difference on my truck and a DRW is the main spring pack, rated at a mere 7% less, and the number of tires on the rear axle. The axles/frame/steering/brakes/etc are all the same. My 9,900 GVWR is not based on the vehicles design capabilities. The 9,000 GVWR on my dad's 06 2500, with all but 1 different part is not based on that 1 different part but the fact that a 2500 needs to be rated lower than a 3500 SRW. That 1 difference is a pair of upper overloads, rated at 1300 lb/in, that are not even in contact with the spring perches at the OEM RAWR of 6,200 lbs.. so they are nothing but useless added weight on a SRW with OEM tires.

 

So.. GVWR is fairly meaningless on a SRW HD truck. On a DRW or a 1/2 ton, or other vehicle, it's fairly important. The GVWR generally tells you what the combination is rated for, just not with a HD SRW truck that shares most of it's parts with a higher rated DRW truck.

 

Some people are not comfortable with this thou, they need to see the payload on the door sticker. These are the same people that will sell a 2500 for a 3500 SRW to gain GVWR when the 2500 is the same truck with very minor rear suspension differences... a rear suspension that is generally designed for more than it can carry on its tires.

 

Only do what you are comfortable with.

 

I have zero issues running my pickup in excess of GVWR, sometimes by 2,000lbs, but I know the design specs, I have upgraded my tires to match my load, and I am registered for the weight. I'm 100% legal, and 100% within design limits.

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