What makes a tow rating?

QC

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This is going to look a little like a troll, and I expect it will cause some disagreement, but this is not a rhetorical question. I have been in the heavy truck business since I was 18, I am 49 . . . with that said I don't know what actually adds up to 10,000 lbs, vs. 7600 in a half ton for example.

Horsepower? Well no, it can't be that. I can buy an 80,000 GCVW truck with less than 300 bhp, and I can buy a 315 bhp Chevy with only 8,000 lbs., so that can't be the whole story.

Frame strength? Well I am thinking of a post recently about watching a Toyota Tundra's frame flex visibly yet it has the highest half-ton rating.

Transmission? Well hmmmm . . . SAAB's and Volvo's have higher tow ratings than any of their US, Japanese and European competitors. But these are typically ZFs which are used in many other cars with lower ratings.

Marketing? Sometimes I think this is the major factor. The examples of the Toyota's with the highest half-ton ratings come to mind. Well . . . Ford, Dodge and GM/Chevy all have 3/4 and 1 tons to move you up to, but Toyota only has a "half-ton". You could argue that Domestic OEMs dumb theirs down to up sell, and Toyota is overaggressive to compensate . . .

So . . . What is it? What factors add up to a high tow rating?
 

summitlt

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Re: What makes a tow rating?

Ya missed a big one... BRAKES.

It seems to be a mix of everything. Another thing is length, a jeep wrangler and jeep grand cherokee. Both with the SAME brakes, engine, tranny and axles have a very different tow rating. Short trucks with a lot of weight get scary when your locking tires and stuff like that.
 

QC

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Re: What makes a tow rating?

Yeah, brakes are a good component to discuss, but IF the trailer is 10,000 lbs and the truck is 5000 lbs curb weight, which brakes are you worried about?

Also, with the length discussion, in Chevy world, the shorter box with a standard cab has the highest rating as it's the lightest truck. This is a good example of my question . . . OEMs treat these combinations differently.
 

edzzed

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Re: What makes a tow rating?

while brakes may be part of the equation, my guess says my 98 gmc 6.5 diesel one ton DUALLY is not rated to tow as much as say a 08 gmc 2500. and I'd think my brakes are bigger than the 08. i also think my limit is 8000lbs. Ed
 

Titanium48

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Re: What makes a tow rating?

I think marketing is the biggest single factor. North American carmakers make money (or used to make money) by selling people bigger, more expensive vehicles than they really need.

In the modern era of big brakes with ABS, braking ability has more to do with the friction of the tires on the road than anything else. Mash the pedal hard and you'll be on the verge of lockup (without actually locking up) until you stop. Your ability to stop an unbraked trailer will depend on the relative weight of the trailer and tow vehicle, while a braked trailer will stop as well as the trailer brakes allow.

As for other factors, there are the "tow packages", which might include better cooling (particularly for the transmission), a beefier hitch and maybe some suspension tweaks. Most of that stuff is available in the aftermarket and is easily added. Cooling in particular can mean the difference between operating at or near WOT for hours without damage and being stuck on the side of the road.

Another factor is North American lubricant specifications. Just about any cheap oil or transmission fluid will meet them, but that doesn't mean they will stand up to hours of near-continuous WOT operation. It's easier to deny a warranty claim because "you exceeded our artificially low towing limit" than because "your oil/tranny fluid met the minimum specifications but wasn't adequate for your application".
 

dingbat

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Re: What makes a tow rating?

I've often wondered the same question.

Got to be marketing and America's "mine is bigger than yours" mentality.

If it was brakes then there would be a disclaimer that the truck would tow X with trailer brakes and Y without.

Don't see how the length of the vehicle could mean much either. It?s the distance from the rear wheel to the hitch point that determines the load on truck?s front axle. You could pull a house with a mini bike with a wheel directly under the hitch point.
 

Dunaruna

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Re: What makes a tow rating?

I don't know this for a fact but I would like to think there is some sort of formula used that takes into account weight/brakes/suspension/chassis rigidity/towbar design & mounting hardware.
 

bowman316

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Re: What makes a tow rating?

But how can a 400 HP tractor Trailer tow 40 - 50 tons?
When that guy who has a diesel truck can only tow 8,000 lbs?
I think the real answer is torque.
I know big rigs also have about ten speeds.
And diesels can tow more than gas engines.
I would think a big diesel pick up could tow 20 tons at least,
whit a gooseneck hitch.
 

avenger79

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Re: What makes a tow rating?

brakes
gear ratio
torque

the other things matter as well but these are important, along with frame strength and length.
 

NYBo

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Re: What makes a tow rating?

I think the manufacturers also calculate the warranty ramifications of the tow ratings they give to their vehicles.
 

Backyardhockey

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Re: What makes a tow rating?

About a year ago I heard there were plans for the manufacturers to get together and have some objective standards in place to come up with a rating. Havent heard anything about it lately. I guess other priorities, like staying in business, have superceded that idea. BTW, does Uhaul still use clamp-on bumper hitches? I havent seen one in years. Thankfully.
 

25thmustang

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Re: What makes a tow rating?

I also wonder, as you can have a 10K trailer set up 15 different ways. A top heavy short wheel based 10K trailer is a lot different than a 40 foot long 10K trailer with a short load...
 

VIPcole

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Re: What makes a tow rating?

I don't know what actually adds up to 10,000 lbs, vs. 7600 in a half ton for example.

calculated by adding the following weights together: The vehicle's listed curb weight, allowable payload, driver and passenger weight and trailer weight.

So . . . What is it? What factors add up to a high tow rating?

Most vehicles have enough power to tow a trailer. A small car or even a motorcycle has the capability to pull a trailer. It?s not always recommended, but it can be done. An average sedan can tow about 1,000 lbs while larger cars and minivans can tow around 3,500 lbs. Go up a step and light trucks and SUVs can tow close to 5,000 lbs with the heavy duty trucks being able to tow much more.

The difference isn?t just the horsepower or the torque of the engine. There are many factors that determine towing capacity. Some of those are:

Horsepower
Torque
Overhead camshafts versus overhead valves
Engine configuration
Axle ratio
Rear wheel drive versus front wheel drive
Engine
Frame design
Hitch-to-car mounting
Wheel load ratings
Tire load ratings
Suspension load ratings
Transmission and oil cooling equipment
Brake size
Electrical systems
Towing capacity is built into the vehicle during manufacturing based on what the company thinks the vehicle will be used for, by whom and where these people live.

And i didnt type all this i just copied and pasted it from another "information place"...:)
 

QC

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Re: What makes a tow rating?

brakes
gear ratio
torque

the other things matter as well but these are important, along with frame strength and length.
Just to re-connect this to my initial question. Yes, all of those things matter, but I guarantee I can find specs where torque is lower on one truck and the tow rating is higher. My favorite example again is the Toyota . . . So if those three things are what matter (they do) why are there multiple examples of the opposite? So, yes, those things are extremely important to you and me, but they don't seem to determine tow ratings at the OEM level, yet you and I all refer to them endlessly as gospel. Which leads me back to marketing . . .

BTW, Duallies have LOWER tow ratings than their single wheel counterparts . . . I just went through the Owners Manual for my 2008 GMC and it is what caused me to post this thread. IMHO, GM/Chevy sits in a room and says, "OK, max GCVW is gonna be 13,000 lbs on our half tons with a 5.3 V8 & 3.73 rears." So then, if curb weight for the single cab with a short bed is 5000 lbs, then the tow rating is 8000. If a crew cab is 5500 lbs, then the tow rating is 7500. They do the same for the 2500s and the 3500s. Dually is heavier = lower tow rating.

And this example (loosely based on the data I just pulled from the Owners manual that covers all 2008 GMC pickup models) is why I have asked this question. We all would be more comfortable with the Dually setup, yet it has a lower rating . . .
 

mthieme

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Re: What makes a tow rating?

While I have no definitive answer to the question, I can pass this on.
The last time I went up to MVA to register a homemade trailer, the clerk at teh counter asked me what was the load rating. You have a choice of 1000, 2000, or 3000. I said the was only 400#. The clerk said it's all the same price, implying that I should go with the max. So I said 3000.
 

180shabah

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Re: What makes a tow rating?

The last time I went up to MVA to register a homemade trailer, the clerk at teh counter asked me what was the load rating. You have a choice of 1000, 2000, or 3000. I said the was only 400#. The clerk said it's all the same price, implying that I should go with the max. So I said 3000.

Except at 3k, you require brakes and an annual inspection.(At least that is the magic number in VA, but I think MD is the same).
 

tashasdaddy

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Re: What makes a tow rating?

why and how, do they tow with smaller cars in Europe.
 

mthieme

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Re: What makes a tow rating?

Except at 3k, you require brakes and an annual inspection.(At least that is the magic number in VA, but I think MD is the same).

Up to an including 3K# in MD does not require brakes.
No annual insp. in MD on anything.
 
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