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seeleylaker · 07-14-2009, 09:31 AM

I find it hard to believe that any manufacturer would actually publish what they felt was the absolute maximum their vehicle would handle. I mean, the truck builder probably looks at the tires and uses that as the guide even though the truck will handle more. The tire guys obviously don't want to put an absolute maximum rating on anything, so they probably reduce the rating by 10 or 15% so those that overload are still close to being safe.

So is the 80% rule logical? Probably not. Is it good rule for those who are uncomfortable assessing their driving ability and the capability of their equipment? Maybe so.

Big Dee · 07-14-2009, 05:04 PM

Quote:

Originally Posted by REDNAX

80% is bull.

Another way to look at it is also simple: Limited travel miles in a years time is one way to decide on a "lesser" vehicle; a 1/2T over a 3/4T truck for example.

And don't listen to those who get twisted panties over climbing long steep grades at WOT at 40 mph for twenty minutes. The engine will be fine and so will you. Traffic now or traffic in the 1960s is an irrelevancy if you have NUMBERS to verify your hitch rigging (Solo & loaded TV & TT weights as a start) and have a well-inspected pair of vehicles. That's all we did then (many traveled with an empty trunk in the TV, for example, back then so as not to overburden the rear suspension).

Keeping lane-centered is the only real criterion; travel speed is a function of safe operation. The Interstate is 45 mph and there may be times one has to travel at that lower speed for a limited period.

80% is for those too lazy to be responsible, IMO. No numbers, improper loading, etc. Just take the time to get things right. A fulltimer has the luxury of spec'ng everything to that one function. The rest of us work with our compromises.

well said and i agree wholeheartedly. when i towed my 30' classic with my HD 1/2 ton, i was told here over and over i was crazy. it was at 90% rating if it was ever fully maxed out. i towed it over the rockies. yes i slowed down to 40 mph but big deal. the rig went right up and over. so what if i couldn't maintain 65 mph at the top of the world. towed great for me all over the country. some people were saying a 1/2 ton shouldn't pull anything over 25'. how ridiculous is that?

InsideOut · 07-14-2009, 05:15 PM

Occassionaly, fine...but slowing down to 35-40 mph on every trip when you live here is a whole 'nother story...

Shari

Diesel1 · 07-14-2009, 05:29 PM

I worked at Ford's Arizona Proving Ground in Yucca, Az till they closed it last year. It was a truck,desert,durability proving ground. When we did tow testing which was 10,000 miles, we loaded a trailer to max GVW for that vehicle. Anything from a F450 to an Escape.The tounge weight was set at 10-12%. We had a stop and go course,and a high speed 5 mile oval that we did on site trailer tow on. However we did about 80-90% of the 10K mile towing on public highways. On the public roads we drove to Bullhead city on highway 68,BHC is at the bottom of a 12 mile long 6% grade.The driver left the proving grounds at the start of the 8 hour shift and drove the 60 miles to BHC. for the next 5 hours they drove op and down the 12 mile 6% grade. We did that 24/7 365 days a year.In the summer 125 degree's is a routine temp along the Colorado river. We did these tests with all our trucks, and all the compediter's trucks. We always tested at 100% GVW. Never 80%. Adios, John

Airslide · 07-14-2009, 05:46 PM

Quote:

Originally Posted by Diesel1

I worked at Ford's Arizona Proving Ground in Yucca, Az till they closed it last year. It was a truck,desert,durability proving ground. When we did tow testing which was 10,000 miles, we loaded a trailer to max GVW for that vehicle. Anything from a F450 to an Escape.The tounge weight was set at 10-12%. We had a stop and go course,and a high speed 5 mile oval that we did on site trailer tow on. However we did about 80-90% of the 10K mile towing on public highways. On the public roads we drove to Bullhead city on highway 68,BHC is at the bottom of a 12 mile long 6% grade.The driver left the proving grounds at the start of the 8 hour shift and drove the 60 miles to BHC. for the next 5 hours they drove op and down the 12 mile 6% grade. We did that 24/7 365 days a year.In the summer 125 degree's is a routine temp along the Colorado river. We did these tests with all our trucks, and all the compediter's trucks. We always tested at 100% GVW. Never 80%. Adios, John

We were out at APG for Volvo and Jaguar and Range Rover. You guys did some very thorough testing. I remember seeing trucks all covered with black masking towing something down the freeway.
Im sure my Ford was tested at 125F heat at one time but now being 15 years old going through the Mohave a few weeks ago nearly killed it! AC off.. windows down and thinking about cranking up that heater!

We made it...

Vin

Diesel1 · 07-14-2009, 05:55 PM

Quote:

Originally Posted by vlamica

We were out at APG for Volvo and Jaguar and Range Rover. You guys did some very thorough testing. I remember seeing trucks all covered with black masking towing something down the freeway.
Im sure my Ford was tested at 125F heat at one time but now being 15 years old going through the Mohave a few weeks ago nearly killed it! AC off.. windows down and thinking about cranking up that heater!

We made it...

Vin

Check your rad, my 1994 1/2 DIT handles the desert well, and ice cold A/C. I love diesels in the desert! Adios, John

Airslide · 07-14-2009, 08:53 PM

Maybe its time to have it rodded out. I just installed a new fan clutch and Im sure that helped. Going up the back side of the Techapies was tough. Maybe the 3.55 rear axle mod from 4.10's too.. I think I should have gone with the 3.73's.

I will pull the rad out and have it checked.

Vin

Diesel1 · 07-14-2009, 10:32 PM

Quote:

Originally Posted by vlamica

Maybe its time to have it rodded out. I just installed a new fan clutch and Im sure that helped. Going up the back side of the Techapies was tough. Maybe the 3.55 rear axle mod from 4.10's too.. I think I should have gone with the 3.73's.

I will pull the rad out and have it checked.

Vin

For towing I have found 3.55 to tall a gear for the Ford diesels. It lugs the motor to much. Adios, John

dmac · 07-14-2009, 11:06 PM

My '05 F150 is rated to tow 8,700 lbs (Supercrew, 4X4, 5.4 liter, 3.73 gears, 18" wheels). My '03 Safari 25SS GVWR is 6300 lbs, which is 72% of the truck rating. Overall it works fine... yet in the mountains the 300 hp is merely adequate, and the transmission gets hot. My aftermarket trans temp gauge climbs to 220-230+ with only a few miles of 7% mountain grade. I have to stop on long hills and let it idle to cool down. I installed a fan on the transmission cooler, but it doesn't seem to do much (I think it's because the fan is defective - noisy bearings and not spinning very fast).

In summary, I don't know where the 80% rule came from. But I would not want any lesser of a tow vehicle than what I have now in the mountains. Flat country is much easier though.

Edit: I found this in the Ford towing guide for my truck...

Maximum Loaded Trailer Weight

assumes a towing vehicle with any mandatory options, no cargo, tongue load of 10-15% (conventional trailer) or king pin weight of 15-25%. (fifth-wheel trailer), and driver only (150 pounds). Weight of additional options, passengers, cargo and hitch must be deducted from this weight.

Road Ruler · 07-15-2009, 05:16 AM

It was said before that most rigs (90%) are not connected optimally.

With these less than optimal to scary connections it is easy to see why many want to reduce the size and weight of their trailers to get a comfortable feel.

flitzwhopper · 07-15-2009, 07:29 AM

Kind of murky water here. Flatlands vs hilly country - go and stop are a big deal. Stop less so if your camper has good brakes. A 3/4 Dodge Ram can have a Hemi with 350 ft lbs torque or a Cummins with over 600. Big difference. Max load is the same for those.
Carry is another deal. Spring rates and the robustness of other suspension parts comes into play here. All in all, for the difference in cost between a half ton and and a three quarter ton, the extra money is worth it.
Lastly, the closer you run any mechanical system to its maximum the more you decrease longevity.

Wingeezer · 07-15-2009, 07:30 AM

Quote:

Originally Posted by Big Dee

i always considered the 80% rule as stupid. i agree with you someone just made this up. never made sense to me. everyone on here always seems to go overboard when it comes to tow vehicles.

Right or wrong, I like to stick with the rationale of remaining somewhat below the vehicle manufacturer's stated maximum tow rating simply because I think that any machine will last longer and operate more reliably if it is worked at something less than 100% of its rated maximum output.

I also have a suspicion that the manufacturer's marketing departments "push" their engineering departments to up the stated ratings for competitive reasons.

Just my approach!

c177tx · 08-18-2009, 03:54 PM

Ok so do you think this was an 80% setup.

YouTube - Car Pulling Trailer Smoking

sorry if this was a repost of this, I was roflmao when I saw this on another fourm

flmgrip · 08-21-2009, 05:25 PM

man... this is getting pretty weird...

guys telling me i don't have the proper connection setup, telling me i should leave my favorite coffee mug at home, telling me i have time to creep over those passes because i shouldn't be in a rush and i'm plain stupid because i went "oveboard" on my TV

hey listen, anyone can toy their trailer with whatever you want, go to 120% if you like. tow a trailer that's 3x times the weight ov the TV. i really don't care as long as you don't kill anyone but yourself in the process... you can go up any hill 30 mph if you want as long as you let faster cars go pass whenever possible, it's all good, everyone at their own leisure.

i, for one, have to work for a living and if i want to get away for a quick weekend trip i want to get to my destination fast, comfortable and safe. almost every single trip of mine involves mountain driving and i enjoy that i have the power reserve to do so at good speeds and without any need of cooling down and pulling over. a weekend is only that long...

saftey is an hole other thing tho... i consider myself a safe driver and try to maintain proper distance etc. at all times. i'm used to driving big rigs and know the wheight involved. the other day however i had a close call where i had no choice but do a full emergency stop. no it was not predictable despite my safe driving method and looking ahead... but boy was i happy to have my "oveboard rig". i was able to avoid an accident, partially because i had reserves in my setup and was able to stop my rig on a dime, without beeing all over the road and endangering others...

i don't know my ratio but i know i'm glad i didn't push the specs on my TV setup to the max... i'm glad my trailer is about the same wheight than my TV...

and my gasmilage drops less than three gallons from no trailer to trailer...

steer axle 4240 (max spec 4800)
rear axle 4020 (max spec 6900)
trailer axle 5280
total wheight 13550 (max spec 18500)

now go out and enjoy your trips safely in whichever way you like...

steverino · 08-26-2009, 10:15 PM

As a private pilot, I've been doing weight and balance calculations for quite a few years. The exercise is to insure that, when loaded, your aircraft's weight and balance fall within the certified limits. I, and most pilots, view the spec as a contract - the manufacturer certifies that a well-maintained aircraft will perform safely within the envelope, assuming normal piloting skills. I would not think twice about loading to exactly maximum gross weight rating and balance limits, but I would offload fuel, cargo, or passengers, if the number came out a single pound above it. to fly outside the ratings could be hazardous to the health of pilot and passengers, or at the very least, turns the pilot into a test pilot, which was not a risk I was willing to take. As well, legal repercussions or invalidated insurance could ensue if an incident occured and the weight/balance was found to be outside of spec.

In my calculations of which TV works with which trailer, I approach the numbers in a similar way. the R in GVWR means "rating", which is the number at which the manufacturer certifies the vehicle will perform to spec. Whatever it is, above that, you are the "test pilot" and should not be surprised if unexpected performance -whether it be maneuverability, durability, or other factor.

Steve

flmgrip · 08-26-2009, 10:40 PM

well said steve... now how many know how much their TV or trailer really weights? i bet a lot would be surpized!

ROBERTSUNRUS · 08-26-2009, 10:47 PM

Hi, simply put,......... 80% of us are set-up reasonably proper and the other 20% are living dangerously.

Gene · 08-27-2009, 06:15 PM

I would be more likely to trust a plane's ratings than those of an auto manufacturer. I think there are a lot more regulations controlling airplane safety than those concerning autos and trucks. The public doesn't accept airplanes falling out of the sky, but does accept badly made trucks and 40,000 deaths/year on the highways.

It's true that if you have accident towing a trailer and are at 95% of truck ratings, you could sue the manufacturer, but the cost of the lawsuit would be enormous. You would have to hire experts who could show the ratings were wrong and the manufacturer would try to prove it was the driver, not the tow vehicle. A class action is difficult and would require hundreds or thousands of truck owners who have had the same experience.

My belief the best thing to do whether or not you use the 80, 85, 90% rule, or go to 100%, is to choose a tow vehicle from a manufacturer that produces the most reliable vehicles that rarely have problems.

Gene

steverino · 08-27-2009, 07:29 PM

Good points, Gene; aviation industry is held to a higher standard than motor vehicles with regard to maintenance, inspection, specification, and pilot qualification.

Steve

hampstead38 · 08-27-2009, 09:34 PM

I assume when you are talking about aviation, you mean commercial flights with highly trained pilots... and where carriers have a strong profit incentive to keep planes from falling out of the sky. Yes, flying in commercial aviation is safer than driving, but I don't think it's about "public outcry." There are about 28,000 commercial pilots in the U.S. and there are about 200 million drivers. As the number would indicate, it's a little easier getting a driver's license than getting a license to fly a commercial jet. Over 40 percent of driving fatalities are alcohol related. Commercial airlines pilots face strict requirements (and sanctions) related to alcohol or drug use. In short, commercial airline pilots are carefully screened, highly trained, highly paid professionals. If you put the same people behind the wheel of Greyhound buses (and paid them six figures)... I imagine the accident rate would be very low.

The single most important factor in safe driving and/or towing is the operator... not the vehicle. I imagine the real 80/20 rule is that 20 percent of drivers cause 80 percent of accidents... people who drive too fast, people who drive impaired, people who drive distracted (talking, eating, texting, etc.). A relatively small percentage of accidents are due to catastrophic mechanical failure. Sure, if you tow at or near capacity, a vehicle is likely to wear out more quickly... but how you drive is far more important than what you drive, at least in this man's opinion.