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What determines towing capacity?

12K views 34 replies 16 participants last post by  dodger889 
#1 ·
Kicking around the idea of buying a tow rig this summer, I can't really go as big with my jeep as I want to until it's got a hauler. I don't honestly have much use for a pick up- I live 7 minutes from work and don't need to haul anything. BUT- I'd really like a vehicle that can tow the jeep on a trailer, be a DD and maybe have luxuries like glass windows :tonka:. So, if I'm looking at say a FS Bronco or maybe a short Suburban or possibly a ZJ/WJ with a V8, what really determines towing capacity?

Frame rigidity?
Tire/Axle size?
HP?
Leaves Vs. Coils and Links? (Not sure about Tahoes and Grand Cherokees for this reason)

what's the most important?
 
#2 ·
the Gross vehicle weight is mostly it, or what every the manufacture says it can handle. for me as an example. My F-150 has a GVW of 7300lbs and I have a class IV hitch (rated to 7500lbs) the most I can haul is 7300lbs (14600lbs total truck and trailer/load).
 
#4 ·
Yes. Vehicles get tow ratings based on testing for overheating, braking when loaded, and acceleration when loaded. There are also durability tests to determine how long the components will live when towing a certain amount.

I personally think lots of vehicles are over-rated in the towing dept these days. Wheelbase is a big factor for me personally when choosing a tow vehicle. Tow with something too short and you'll figure it out quickly.
 
#11 ·
I agree, and think some are underated. My '99 Suburban with 5.7L and 3.73 gears is only rated to tow 6000lbs. but my 95 ZJ w/4.0L is rated for 5000lbs. My '01 Explorer Sport Trac w/4.0L is rated to tow 5500lbs. How can those two small 6cylinder vehicles be rated just under what the big Suburban is rated for. I also think the Suburban is underated.
 
#5 ·
Actually it is the GCVW: Gross Combined Vehicle Weight. That is the rated GVW of your vehicle plus the weight of your trailer on contents. They have a tenedncy to overate the vehicles. Which means you can pull it, under optimal conditions.
I've seen a fair share of 1/2 ton and SUVs overloaded on the open road. Some people doing some pretty scary shit out there.

The difference between genius and stupidity is that genius has its limits" - Albert Einstein

Do yourself a favor and go 3/4 ton if you can.
 
#9 ·
Actually it is the GCVW: Gross Combined Vehicle Weight. That is the rated GVW of your vehicle plus the weight of your trailer on contents. They have a tenedncy to overate the vehicles. Which means you can pull it, under optimal conditions.
I've seen a fair share of 1/2 ton and SUVs overloaded on the open road. Some people doing some pretty scary shit out there.
Do yourself a favor and go 3/4 ton if you can.
that's exactly what I want to avoid: I've seen some scary crap on the e-way myself over the years... My thing is that I don't really have a need for a gigantor truck, and at 4+ a gallon, a diesel is certainly out. I don't want to overload a Grand Cherokke, and I know people who tow with them, but it seems a bit small for dragging a jeep and trailer around. I'm thinking about finding a late Bronco, maybe.
 
#10 ·
just get a 1/2 ton truck then, fuel mileage won't be that different from a Full size bronco.

and the longer wheelbase will only help it on the highway.


or split the difference and a get a Tahoe
 
#13 ·
When it comes to towing, the heavier the tow vehicle, the better your towing experiance will be. If you have a 2000 pound trailer and 4500 pound jeep (assuming its on the heavier side), you should be ok with a 1/2, or 3/4 ton pickup. If you want to spend the bucks and need something to pile the family in than I would suggest a Suburban.
 
#20 ·
Can I park it at your place? :tonka: I can barely fit 3 cars in my driveway, and the Jeep won't fit in the garage anymore. I'm thinking a mid-90's something. What about a reg cab 3/4 ton?

AND: Does it have to be 4wd? Does that make a difference in towing ability? Other than on snow?
 
#15 ·
Remember those published numbers are the max rated GCVW. As you approach or exceed those numbers your safety factor decreases. If your rated at 5k and towing 5k you might want something more.

I personally don't like towing with IFS anything, but thats just preference.
And just to keep things in perspective, I can visualize the difference between a Dana 35/44 axle and a Dana 60/70.
A half-ton pick up is for towing a couple sleds and transporting the family dog or occassional fat chick.
 
#16 ·
I first look at the weights. If what I'm towing with is close to what I'm pulling, I'm OK. But if your tow rig is lighter than the load, I be scared unless you take proper precautions (the right brakes, the right hitch, the right tires, the right trailer, etc...)

My parents '03 Yukon with 5.3L & 3.73's is rated higher than my '94 burb with 7.4L & 4.10's 3/4ton....for sale BTW...

Lucas
 
#25 ·
Funny this thread came up. I had asked this question not too long ago of a couple of truck engineers while I was out at the test track. While yes, there's alot of legal dealings that go into the PRINTED figures, they actually do test the ability rather interestingly.

First is the straight line tests. Accelleration and braking are done to determine fall off points and acceptable levels.

Second is the fun part. They have this fancy trailer that basically can sideload the trailer hitch of the vehicle to actually try and fishtail the tow rig at 25mph, 55mph, and 70mph to see what kind of side loads the vehicle can take. They come up with some slide rule math to determine the acceptable levels and they present the data to the lawyer types that typically recommend a level somewhat below the tolerance points. I thought it was kind of neat.
 
#26 · (Edited)
My first enclosed trailer, towed with my old show truck, short box and 35" tires = trailer sway and loss of control. Flipped the trailer back on it's wheels and drove the Jeep out of the trailer and the rest of the way to the Dunes and then back to Midland.

Moral of the story, dont tow with a short box lifted truck on C Rated 35" tires!

The truck and trailer were totalled by the way.


 
#28 ·
My first enclosed trailer, towed with my old show truck, short box and 35" tires = trailer sway and loss of control. Flipped the trailer back on it's wheels and drove the Jeep out of the trailer and the rest of the way to the Dunes and then back to Midland.

Moral of the story, dont tow with a short box lifted truck on C Rated 35" tires!

The truck and trailer were totalled by the way.


So, by the "seat of your pants" gauge. Was the issue primarily the tow vehicle or do you think weight distribution came into play.
 
#31 ·
To add to my story, we were on US 10 or "old 10" as it's also known. We were on the West side of the town of Baldwin approx ten miles or so on a stretch of road that curved and had a double hump in it. This set off one of the worst trailer sway conditions ever witnessed by those who scattered from their locations either behind us or coming at us.

US 10 was 3 lanes at this spot and we used all three before spinning 180 degrees and hitting a guardrail bringing us to a stop as the trailer flopped. No ticket was issued as the local fire dept. said we were not the first trailer accident at this spot due to the same sway issue coming over the double hump and through the curve. Comforting huh?

US 10 was closed for two hours while they cleaned up the 22 gallons of fuel and righted our trailer back to it's wheels. Which leads me to mentioning, do not fill your gas tank on your trailered vehicle if you can help it. Do it once you reach your destination, only you can prevent road fires!
 
#32 · (Edited)
To add to my story, we were on US 10 or "old 10" as it's also known. We were on the West side of the town of Baldwin approx ten miles or so on a stretch of road that curved and had a double hump in it. This set off one of the worst trailer sway conditions ever witnessed by those who scattered from their locations either behind us or coming at us.

US 10 was 3 lanes at this spot and we used all three before spinning 180 degrees and hitting a guardrail bringing us to a stop as the trailer flopped. No ticket was issued as the local fire dept. said we were not the first trailer accident at this spot due to the same sway issue coming over the double hump and through the curve. Comforting huh?
By seat of your pants, I bet you checked yours!!

I've had that wobble start and the springs pick it up and something about the harmonics that you have to come to a complete stop to clear it.

Nice looking dodge!!! Nothing tows like a dually!!

But have you ever noticed the front track on most (all?) trucks is a little wider than the rear? Not a dually of course, but still....
 
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