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Old 01-27-2013, 07:24 AM   #1
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CAT Scale and Tow Ratings

I have studied the “actual” tow rating sticky thread and its analysis for quite some time, and I think there is another approach to the calculation. Here it is; take your TV (without trailer) to the CAT scale loaded with the items you would carry in it. Then subtract this CAT scale measurement from the published GCWR for your TV to arrive at your specific towing capacity, provided that adding the trailer won’t exceed the TV’s GVWR or GAWR in the process.

Am I correct in this approach Rustic Eagle?

Continuing on with this,
My TV has a GCWR of 16,000 lbs. If I were to change the rear end gearing to the next taller gear, the GCWR would jump to 18,500 lbs. In this scenario, the brakes have not changed nor has the chassis, the steering gear or tires. It seems that only the hill climbing ability is considered here, and not the other factors which go into road handling safety. Am I missing something here?
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Old 01-27-2013, 07:58 AM   #2
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Hi, you need to also consider that the most important measures (GVWR and payload) neither of these have increased with the gear change. You can drag more but you can't load more, this is what gets most 1/2 ton owners into trouble. They get the high gear ratio and then think they can haul the Queen Mary. The towing capacity becomes unreachable unless the vehicle is driven with no payload or options on the TV and only thevweight of a 150 lb driver.....not to many of these around!

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Originally Posted by David472 View Post
I have studied the “actual” tow rating sticky thread and its analysis for quite some time, and I think there is another approach to the calculation. Here it is; take your TV (without trailer) to the CAT scale loaded with the items you would carry in it. Then subtract this CAT scale measurement from the published GCWR for your TV to arrive at your specific towing capacity, provided that adding the trailer won’t exceed the TV’s GVWR or GAWR in the process.

Am I correct in this approach Rustic Eagle?

Continuing on with this,
My TV has a GCWR of 16,000 lbs. If I were to change the rear end gearing to the next taller gear, the GCWR would jump to 18,500 lbs. In this scenario, the brakes have not changed nor has the chassis, the steering gear or tires. It seems that only the hill climbing ability is considered here, and not the other factors which go into road handling safety. Am I missing something here?
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Old 01-27-2013, 09:20 AM   #3
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I like the 3:73 gear ratio on my ford. The real low ratio one gets the best gas mileage but doesn't pull much and the real high ratio one will pull the most but at the expense of real poor gas mileage. For me seems the one in the middle being the 3:73 gear ratio works out the best for me for pulling my 4200LBS OFF-ROAD POPUP. My truck gets almost the same gas mileage whether it is pulling the trailer or not. i.e. it hardly knows the trailer is back there since the wind resistance is low.

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Old 01-27-2013, 12:35 PM   #4
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Thanks for the replies so far. The reason I've been studying this topic again, and more closely than before, is we are weighing the pros and cons of getting a larger trailer. Besides the usual floor plans and CG size restrictions, I want to measure and calculate the capabilities ahead of any deal making. So, I won't have the trailer to take to the CAT scale. During the process of becoming familiar with the new-to-me 3/4 ton truck, the 2 items I touched on in the original post came to mind.
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Old 01-27-2013, 01:30 PM   #5
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Another suggestion is to ask on here when you are deciding on a FP. Someone may already have one that has been weighed for a more accurate comparison.

IMO, this would be more accurate than the cargo carrying capacity listed by the manufacturer. At least something to compare.
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Old 01-27-2013, 01:34 PM   #6
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Quote:
Originally Posted by David472 View Post
snip...... take your TV (without trailer) to the CAT scale loaded with the items you would carry in it. Then subtract this CAT scale measurement from the published GCWR for your TV to arrive at your specific towing capacity, provided that adding the trailer won’t exceed the TV’s GVWR or GAWR in the process.....snip
David,

Yes, that would give you a close ballpark on how much TT weight you could tow..., and when you go to the CAT scale also have your WDH ball mount attached to your TV. As you mentioned then you would have to consider the remaining weight value between the TV's loaded CAT scale weight and it's specified GVWR (ie; remaining payload weight as 'Ron' mentioned) which is what is available for the loaded tongue weight.

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snip...... My TV has a GCWR of 16,000 lbs. If I were to change the rear end gearing to the next taller gear, the GCWR would jump to 18,500 lbs. In this scenario, the brakes have not changed nor has the chassis, the steering gear or tires. It seems that only the hill climbing ability is considered here, and not the other factors which go into road handling safety. Am I missing something here?
Basically the higher gear has direct impact on the existing drivetrain's ability to tow a load, but as mentioned doesn't (in most cases) increase the same vehicle's GVWR and/or payload capacities. As you stated other factors would have to come into play for the GVWR and/or payload capacities to increase as well. This is where manufacturer's specifications push customers into 3/4 and 1 ton trucks. As far as the TV's brakes they are spec'd to stop the TV's GVWR only, and the TT's brakes are designed to stop it's specified GVWR.

Interesting thread, keep us up to-date as you move forward on your TT selection and associated weight considerations.

Bob
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Old 01-27-2013, 01:48 PM   #7
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David,

As you proceed with your do-diligence looking at heavier/longer TT's, IMO you would be better served using the 13% to 15% rule for a loaded tongue weight range (lieu of 10% to 15%) with the longer TT's. So when you are making loaded TT weight assumptions during your search you may want to keep this in mind.

Bob
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Old 01-31-2013, 02:12 PM   #8
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Quote:
Originally Posted by Rustic Eagle View Post
David,

As you proceed with your do-diligence looking at heavier/longer TT's, IMO you would be better served using the 13% to 15% rule for a loaded tongue weight range (lieu of 10% to 15%) with the longer TT's. So when you are making loaded TT weight assumptions during your search you may want to keep this in mind.

Bob
Bob,
With our current TT we are at 12% tongue weight, by the scale. So, what you say makes a lot of sense.
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Old 01-31-2013, 02:46 PM   #9
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Well, I made the trip to the CAT scale, and for those of you who might be interested, this is what we got;
Full tank of gas, driver, passenger and Equalizer hitch head on board. We carry very little else in the truck. Maybe another 150 lbs max of misc stuff, which I'm not too worried about at this point. Just wanted to see roughly where I'm at.

GCWR - Spec 16,000 lbs
GCWR - Scale 6460
Difference 9540 -approximate tow capacity

GVWR - Spec 9200 lbs
GVWR - Scale 6460
Difference 2740

GAWR(F) - Spec 4200 lbs
GAWR(F) - Scale 3640
Difference 560

GAWR(R) - Spec 6084 lbs
GAWR(R) - Scale 2820
Difference 3264 -approximate 5er pin capacity

The engineering side of me is still pondering the Spec on GCWR. The identical RAM truck is rated 1,000 lbs more and the identical Ford truck is rated 3,000 lbs more. I'm not convinced there is that much real difference in GCWR between the gas engine and transmission offered in each of the three. Has me thinking, when does that new towing standard come into effect?
Not yet I bet.
Also - A nice amount of 5er pin capacity if we go that way.
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Old 01-31-2013, 03:39 PM   #10
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David,

Very similar weights as my '02' GM 2500HD..., and with your specific CAT weight data you have a good reference point to work with while looking at a new TT or FW.

Minor acronym clarifications:

Quote:
Originally Posted by David472 View Post
GCWR - Spec 16,000 lbs
GCWR - Scale 6460 Should read: GVW
Difference 9540 -approximate tow capacity

GVWR - Spec 9200 lbs
GVWR - Scale 6460 Should read: GVW
Difference 2740

GAWR(F) - Spec 4200 lbs
GAWR(F) - Scale 3640 Should read GAW(F)
Difference 560

GAWR(R) - Spec 6084 lbs
GAWR(R) - Scale 2820 Should read: GAW(R)
Difference 3264 -approximate 5er pin capacity

....... snip
Some Automotive Manufactures are specifying their weights under the new rules.., don't know what the deadline is for all manufactures to be on board.

Bob
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