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View Full Version : Can my bla bla bla pull my bla bla bla?


flybouy
01-16-2017, 09:17 AM
I see a lot of these posts on this forum and have read some excellent, and some not so excellent advice. So just going to throw out some advise from an old gearhead that's had a few years of experience. First, a little review on the gearhead chalk board.

Horsepower - 2 ratings: 1 at the crankshaft, 2 at the driven wheels.The manufacturers advertise the rating at the flywheel because it's larger, both ratings are maximum or peak (as in the peak on the graph before it falls off). What they don't advertise is the RPM that the peak hp shows up. For gasoline fueled it's typically over 3,500 rpm and may be up to 5,000 +, diesel is typically below 3,000 rpm.

Torque - gas fueled engines again are peaked out at higher rpm vs diesel. Typically diesel fueled engines have a greater hp/torque ratios and operate at lower rpm ranges which results in longevity and greater fuel economy.

What does this mean? Well if a prizefighter's punch was rated this way the HP would be how fast he can throw the punch with no regard to impact. The Torque of the punch would be how hard the punch would impact.

Transmissions - they transmit the engine power to the drivetrain. The purpose of the gearing is to mach the specific engine to the specific task. One ratio for inertia from zero movement to one speed, from that speed to another speed, etc. If you have ever ridden a bike with gears you know that you need need a different ratio to pedal up hill that on level ground. When yo shift into a "lower gear" to pedal uphill your legs must go faster to maintain the same speed, just as your vehicle downshifts and the engine speeds up to do the same.

The differential gearing is is a ratio of how many times the driveshaft must rotate in order for the drive wheel to rotate one time. Just like that bike, the sprocket on the pedal is different than the sprocket on the wheel.

Now, given this long winded dissertation I hope this may help some folks understand what all those numbers mean. Fair warning, don't dwell on these numbers! When it comes to towing that is a very small percentage of the numbers that you need to get a clear understanding of what I can or cannot tow. Whats that you say? "I have the weight of the towed object what else would I need?"

Towed object information - yes weight is a major factor but how about the drag coefficient? That's the wind resistance the object presents. Remember as a child when you stuck your hand out of the window? Recall (other than your parents yelling at you) that when your hand was parallel to the horizon the fore against was was lot less than when your hand was vertical? Same physics apply, a 3' high tent trailer will offer lower wind resistance than a 13' fifth wheel. Then there's the parasitic drag, the side wall surface area that not only presents drag in a forward motion but acts like a huge sail surface during crosswinds whether from nature or a passing bus or semi rig. How about where the rubber meets the road? What's the number of tires on the ground? Two? Four? Six? What's the rolling resistance of those tires?

Lot's of calculations right? What's the consumer to do other than buy time on a super computer at MIT and run the numbers? My advice is to try it before you buy it. If your looking at a new trailer ask the dealer if you can hitch it up and go for a drive. Feel how it reacts to your truck and terrain and remember that this is best case scenario as the trailer will be at it's lowest weight until the day you empty it out to sell it. The reverse if your looking at a new truck, hitch it up to your camper and go for a spin. I know this is more challenging for the "fiver folks" but most people with 5 th. wheeler seem to be more experienced. I'm of the opinion that a number of folks asking the questions "will my truck pull this" already suspect it won't and are hoping against hope that someone will say it's O.K. I speak from experience, I've had the Chevy S10 that towed the pop up with ease and purchased a hybrid camper that was was within the tow weight. Lots of downshifting on winy days on level roads, white knuckled days in wind and passing trucks, then 1/2 ton and "now I can tow more" so repeat the process until 3/4 ton truck and 35' trailer.

So this is just my advice for what it's worth - try it, if the dealer won't let you try it out then seek out another dealer and you can't go wrong with going big on the tow vehicle. Excess capacity on the tow vehicle will add to the safety margin and facilitate the inevitable "We need a larger trailer" day that seems to haunt us all.

chuckster57
01-16-2017, 01:22 PM
Good information. It seems like the most robust discussions are based around weights.

What a federal sticker says vs. what the TV has been tested to by any particular member.

The other topic that seems to invoke lots of posts is the XXX is "the exact same thing" as XXX...

So "Can my bla bla bla pull my blah bla bla" is a multi faceted subject, thank you for taking the time to explain what you did.

ctbruce
01-16-2017, 06:36 PM
Great information. Very helpful and clear.

Chip Bruce, RPh
Kansas City, MO
2016 Fuzion Impact 312
2015 Chevrolet Silverado LTZ
WELL....THAT WAS FUN!

CWSWine
01-16-2017, 07:03 PM
Most of the what my truck can pull is based on the website towing capacity specs. My GMC 3500 website says the towing capacity is 17,100 pounds but they are using pin weight of 15% so that would be a payload of 2565 pin weight but in the real world most 5er with 17,100 ready to camp weight would be close to 23% which would give it pin weight of 3933 pounds. The 3933 pin weight plus hitch and passengers would be over just about any SRW 1 ton from all the manufactures.

Truck salesman and RV Salesman pray on people with tow capacities ignoring payload. I went to a RV show and I heard at least a dozen times salesman telling people that their trucks could pull XYZ 5er when even the dry pin weight would over the trucks payload trying to using tow capacity. Including using dry payload and UVW to convince the person he will be way under his specs.

Ken / Claudia
01-16-2017, 10:35 PM
Good advice. I agree most asking if they can pull x with y for reasons I do not understand will do so anyway but, know it's not right and want someone to say it's OK. Clearly there are those that do not understand that stuff and want to do right.
As I have said to any who want to listen. You cannot have to much tow vehicle EVER as far as towing. If you can park a 26ft long pickup in the garage or not is different. Also if you like RVing (same as boating) you will almost always want a bigger one after that first one.

CaptnJohn
01-17-2017, 11:07 AM
Most of the what my truck can pull is based on the website towing capacity specs. My GMC 3500 website says the towing capacity is 17,100 pounds but they are using pin weight of 15% so that would be a payload of 2565 pin weight but in the real world most 5er with 17,100 ready to camp weight would be close to 23% which would give it pin weight of 3933 pounds. The 3933 pin weight plus hitch and passengers would be over just about any SRW 1 ton from all the manufactures.

Truck salesman and RV Salesman pray on people with tow capacities ignoring payload. I went to a RV show and I heard at least a dozen times salesman telling people that their trucks could pull XYZ 5er when even the dry pin weight would over the trucks payload trying to using tow capacity. Including using dry payload and UVW to convince the person he will be way under his specs.

While talking to my salesman at CW waiting on service a couple pulled up in a new 2500 Duramax. They looked at the 40'+ Landmark and indicated interest. When asked about their TV they indicated the 2500. The Landmark dry PW was well over 3000#. The salesman said "let's look at the CCC on your truck". Buyer says "no need to, Dumbass. The truck salesman said I can pull every 5er made" they stomped off and left. Bet they found someone that happily sold them a 5er way over payload and possibly 1 or more additional ratings. I want to believe most camper and truck sales people do not know any better and blame the dealerships/manufacturers for lack of training/informing. When in the market for a new TV a while back a sales manager located one of interest at a nearby dealer. I asked for a photo of the yellow sticker prior to committing. I had to educate him on where it was and why important. He had to educate the sales manager at the other dealership. When I arrived to pick up the F350 he had an F150, 2 F250s, and my F350 out front. All salespeople were brought out and handed a copy of towing weights for all. Yellow stickers were compared along with printouts. Our talk session lasted 20 - 25 minutes. Two customers waited about 10 minutes as it was thought this very important. Under new ownership doubtful any info was passed on to new employees.

Scalemaster
01-21-2017, 04:35 PM
Great advice. We pulled our 5er for a couple years with a silverado 1500 max tow with 3.73 rear end. The big 6.2 gaser would pull this trailer all day long up hill and down. Handling was never an issue. The problem was on the rear axle. We were at our capacity with the trailer empty. I got tired of thinking about the overweight condition and upgraded to a 2500 Duramax. Love the big torque at low rpm. Now more worries about overweight. It was worth it.