Impressed with Towing (6600lbs)

550lb. Max Tongue Weight?

Where does the 550lb. max tongue weight spec. come from? The new quick release hitch I just purchased states 770lb.

It's stated on the website and in the owners manual. My hitch said the same thing, but the rest of the documentation says 550lbs.

Rob

Maybe the hitch itself is rated for 770lb but the truck is rated for 550lb?

I just came across this response on an RV thread:

"The Land Rover hitch receiver will actually take 770lbs. of tongue weight even though the manual says it will only deal with 551lbs. The reason the manual says 551lbs. is due to the weight limit of the ball mount that Land Rover sells. The hitch receiver has a 2" opening and most ball mounts that fit that size receiver (that I have seen) are rated for 500 - 600lbs. of tongue weight so be sure not to exceed the weight limit of your ball mount."

Whether or not this is correct, I don't know. It just might explain why there are two different ratings.

Here is the link:

http://www.rv.net/CFORUM/index.cfm/fuseaction/thread/tid/22851742/

It is the 6th post down.

One other thing that I feel I need to mention with the ball mount issue and load ratings. At one time, the manual said there couldn't be more than 2 1/2 inches of rise for the ball mount on the Land Rover vehicles. I read through teh post from the thread you provided. It said the guy used 9" of ride to meet his TT hitch height. I understand that he was most likely using one of the early generation recievers that sat extreemly low. The new one is easily 3" higher than the old one, so that should work in your favor.

I would deffinatly do some more home work and maybe even call LRNA to get some real answers. Hopefully they can provide you with something more tangable that what we are guessing at here.

Rob

Marfnarfle,

Glad to see you found your way over here.

I forgot to mention I checked on the crossbars again today; same thing. I will keep looking to see where they are and when they get delivered to you.

Rob

Hi Rob!

Thanks for the welcome and glad to be here. I had been lurking for awhile.

I think I will call LRNA to find out exactly what the story is with tongue weight. I had seen the 550/770 debate mentioned elsewhere with no one having a definitive answer. I will post what their response is when I get it.

Also, thanks for the help with the crossbars. I am tracking as well and will let you know when I take delivery.

Greg

Please let us know if they have anything definitive.

Here are some LR4 ratings and calculations I did awhile ago:
Base Curb Mass: 5617
Gross Vehicle Weight: 7143
Gross Axel Weight Front: 3197
Gross Axel Weight Rear: 4090
Tongue Weight: 551
Tow Rate: 7716
Unbraked Trailer: 1653
Gross Total Weight: 14853

Calculations:
GTW-BCM = 9242: This is the weight available for trailer, cargo, and people
GVW-BCM = 1526: This is the weight available for cargo and people
GAXR-50%BCM = 1281.5: This is the weight for people+cargo+trailer that can be added to the rear axel (assumes 50% of BCM is on rear wheels, which could be off a fair amount)
GAXR-50%BCM-TW=730.5: This is the rear axel weight available after a 551 lb trailer tongue is taken out.

Making some assumptions about weight distribution...after my wife, myself, and my 2 year old are seated in the car with a full trailer tongue weight added, we have 528 pounds available for rear cargo.

From this it would seem to me that the suspension...which doesn't know the difference between a trailer or any other normal force to the rear axel...has the ability to take significantly more than 551 lbs assuming you stay within the 4090 rear axel limit. So, the limit may be due to the structure that supports the trailer hitch, or it could be due to the wheelbase limit. Any weight reduction to the front wheels would be increase if the vertical force is moved to the edge of the vehicle rather than directly to the rear axel, so perhaps that is an important limitation. Another possibility is that they are factoring in a moment arm for the force of the trailer causing additional load compared to a load within the vehicle when increased force due to bumps in the road is applied.

If your calculations are correct, I have overloaded my LR4 substantially. I have had 7 adults in the truck plus luggage inside and on a hitch mounted hauler. I suspect we were over 1200 pounds just in people plus all the luggage for two weeks in Europe. 7 bags at 50 pounds plus carryons, purses and other personal bags. I would say we were just shy of a ton.

Rob

I just talked with LRNA. They have no specific answer as to why the manual gives a 550lbs. max tongue weight when the hitch is rated at 770lbs. They then recommended I call a local service center. So I called the local dealer and they had about the same answer:

"If the manual states 550lbs., then that's what it is."

Neither one could tell me specifically what the limitation is. Oh well, so much for answers!

BTW, Rob, did you carry your Disco across the pond with you, or did you rent one while you where there?

Greg