Does Payload (lbs) affect tow capacity

[RoyJ]

Ok, I might not have been clear. I am only running a trailer at 3000lbs at a time. My question is when the trailer is attached. How can I determine the interior payload remaining or available after the trailer is attached?

Simple. You should aim for roughly 10% of total trailer weight as your tongue weight.

If your battery load is 3000 lbs, and your trailer is say, 1000 lbs, your total is 4000 lbs. Your tongue should be around 400 lbs.

Your payload is reduce by 400 lbs minus the weight of the driver (you).


Now, before all the safety police say you should aim for higher than 10% tongue weight, keep in mind we're talking about a highly concentrated, low center of gravity load - batteries. It won't induce nearly as much sway as your typical travel trailer, which is light, high center of gravity, and very large in side profile...

 

[ticklemenono]

Simple. You should aim for roughly 10% of total trailer weight as your tongue weight.

If your battery load is 3000 lbs, and your trailer is say, 1000 lbs, your total is 4000 lbs. Your tongue should be around 400 lbs.

Your payload is reduce by 400 lbs minus the weight of the driver (you).


Now, before all the safety police say you should aim for higher than 10% tongue weight, keep in mind we're talking about a highly concentrated, low center of gravity load - batteries. It won't induce nearly as much sway as your typical travel trailer, which is light, high center of gravity, and very large in side profile...

Thanks! Nail on the Head...

 

[Jwestpro]

Simple. You should aim for roughly 10% of total trailer weight as your tongue weight.

If your battery load is 3000 lbs, and your trailer is say, 1000 lbs, your total is 4000 lbs. Your tongue should be around 400 lbs.

Your payload is reduce by 400 lbs minus the weight of the driver (you).


Now, before all the safety police say you should aim for higher than 10% tongue weight, keep in mind we're talking about a highly concentrated, low center of gravity load - batteries. It won't induce nearly as much sway as your typical travel trailer, which is light, high center of gravity, and very large in side profile...

Not true. This 10% thing is a BS USA idea that the rest of the world does not subscribe to at all.

 

[ticklemenono]

Not true. This 10% thing is a BS USA idea that the rest of the world does not subscribe to at all.

well... do you have another suggestion?

 

[Jwestpro]

well yes, when you have the option, like how you load the trailer and/or what cargo is inside the vehicle, don't add so much forward weight such that the tongue weight goes so high.

for example, if towing near the listed weight limit or 7700 lbs with a brake controller, it will certainly not hurt to have the tongue weight a bit lower than 10%.

another example is like if you had a travel trailer and the TW was getting high, you could relocate the items usually on the front A frame like the propane or batteries. It could change an 800 lb TW to 700 by putting those items on the middle or farther back.

Read up on the Can-Am website for more info.

 

[ticklemenono]

will do, thanks.

 

[Jwestpro]

to be clear, one should obviously not go too far the opposite direction loading too much in the rear but getting the weight balanced more over the trailer axles is a good thing with a little toward the front.

however, now that you are talking about lots of trips, what is the least number of batteries you could get away with taking out on any given trip? It could be worth considering only taking what the vehicle will load inside, especially if you could make your route dropping off several in a short distance. I wouldn't hesitate to put 20 of them in the vehicle, especially if you put several into the 2nd row floor. 20 at 25 lbs each it 1500 lbs. I'd even consider 25 at a time, maybe 30 30 = 2250 lbs. If you're driving alone and can drop 5 in the first segment, no big deal. Way better fuel economy getting up to speed slowly but not having the massive aero-brake of a trailer on the back.

I realize there may be benefits to having them go into a trailer though too.

 

[RoyJ]

Not true. This 10% thing is a BS USA idea that the rest of the world does not subscribe to at all.

I'm being VERY conservative here, as not everyone is comfortable with lower tongue weights.

Over on RV.net, I get blasted for even suggesting 10%, some folks think anything less than 13% is a "death trap"...

Personally, I've yanked 130,000 lbs B-trains all over the BC rockies, so I'm fairly comfortable with trailers.

 

[Jwestpro]

What the hell is a B-train? I want to see a photo

Ever seen the European travel trailers? It's pretty cool to see the wheels practically in the center of the mass and read 180 kg tongue weights on 8-9meter trailer. Even the Euro Airstreams have the wheels moved forward.

 

[RoyJ]

What the hell is a B-train? I want to see a photo

Ever seen the European travel trailers? It's pretty cool to see the wheels practically in the center of the mass and read 180 kg tongue weights on 8-9meter trailer. Even the Euro Airstreams have the wheels moved forward.

I sure have, and that's exactly the reason in Europe, compact cars can tow "caravans" weighing up to 3500 lbs.

Can we do it? Sure, laws of physics and aerodynamics are the same anywhere on earth. Why don't we? The lack of competent drivers in North America...

Look up Andy Thompson if you haven't hear of him. I've been a big proponent of his systems for years. He has successfully towed 7000+ lbs airsteams with various family sedans, ranging from Intrepids, to 300Cs, to 7-series, to minivans. He's shown them to beat just about every pickup truck combo in emergency slaloom maneuvers. They all use the Hensley Arrow hitch.


Not sure if you're serious about the b-train (aka super-B, mountain double), but here's what they look like:

In contrast, here's an "a-train":

The a-train uses a conversion dolly for the 2nd fifth wheel. This is less stable, and not allowed in BC due to our mountain terrain. They're also nearly impossible to backup without un-hooking.

A b-train's 2nd fifth wheel is built into the rigid tri-axle portion of the first trailer.

 

[Jwestpro]

Yes, euro balanced caravans, exactly what I have in mind. A Kimberley tandem model to be specific.

That B-train stuff is very cool! Thanks so much for showing such an informative and visual example.

 

[99Discovery]

The 10% rule of thumb really sucks in the states. The Range Rover MKIII (and I think LR4) has a 7700lb towing capacity, but a tongue weight rating of around 550lbs. You could easily get a Euro-caravan in the 7k range with a 500lb tongue if they center the axles right. Try finding one like that in the states? No way. 10% minimum, meaning 5k travel trailer tops. . If you have a slide, you are looking at 600~700lb tongue weight on a 5k trailer. Not a problem at all for my 2500HD (it loves it), but it sucks when I want to camp in one vehicle instead of having my wife drive behind the truck in the overlander.

To the OP, the tongue weight is going to be your limiting factor, but if you are only loading the trailer to 3k, you should be fine unless your batteries are all stacked on the front a-frame .

Try to find the local scales in your area and test-weigh your first loads. It will make the math easier and far less "academic", which can have huge errors. You should be able to easily decipher the weight over the trailer axles, rear axle of the LR4 and the front axle of the LR4.

Axle ratings for your trailer can be easily determined, and the rover's should be on the inner driver door.

GCWR is the total rating of the LR4 and the trailer. Stay under it.

Each axle weight should be less than the rated axle. Any cargo you put in the LR4 will be distributed on these numbers. If the rear rating is over and your front has capacity, move more batteries in the front seat or front bench compartments to get them on the front axle. it IS possible to be under your GCWR and GVWR but OVERLOAD a rear axle. Many believe you can "fudge" the other ratings, but do NOT exceed an axle rating (and by not exceeding an axle rating you won't exceed GVWR. You could exceed GCWR if your trailer tongue weight is light and the trailer is heavy, but as mentioned earlier in the thread if you know what your doing it may not be an issue......exceeding axle capacity IS!

Again, GVWR is just the sum of your axles, so it won't be exceeded if you stay under each axle.

If everything clears, I wouldn't stress too much about tongue weight. Honestly, is the LR4 hitch that bad that it can't take 700lb tongue weight? I thought I've seen a thread where the hitch itself says it's rated for more than that. Why the 500lb rating? Air-springs?


ALSO:

If the numbers check out, make sure you have enough inflation for your tires (their ratings are on the sidewall). If you have "weak" tires, you might be pushing your weight rating with an empty LR4, so don't even think about a trailer. Sadly, lots of 19" and 20" tires are junk. Land Rover should be ashamed for putting that rubber on such a heavy vehicle, much less an off-road one. If you have aftermarket rims, you may want to find your receipt and look for their weight ratings. Some rims are made for mall-crawler SUVs and cars looking for the "hot wheels" look, and they may not be rated for much more than your empty LR4. Stock wheels will be rated for your axle/GVWRs; again, stay under these numbers.

You may need LR-E tires, which should be just fine (I believe some people make 20" LR-E. I would assume 50-60 PSI for a full load like that, most manufacturers of LR-E tires have inflation/weight ratings in PDF format for download.

Then make sure you have a break controller with trailer breaks and you should be JUST FINE.

Honestly, doing it "virtually" is a waste of time. What if your batteries weight 26lbs. or 27lbs? You could get into trouble fast. What if the trailer weighs 1000lbs empty. Or your LR4 is pushing 6000lbs with a full tank of gas and your butt in the driver's seat. Now your disco's capacity is much less than listed in your owner's manual.

Go to a scale. Do it right. Some are free, but even a CAT scale should only be $10 or so.

Good luck!!

I'm being VERY conservative here, as not everyone is comfortable with lower tongue weights.

Over on RV.net, I get blasted for even suggesting 10%, some folks think anything less than 13% is a "death trap"...

Personally, I've yanked 130,000 lbs B-trains all over the BC rockies, so I'm fairly comfortable with trailers.

 

[RoyJ]

The 10% rule of thumb really sucks in the states. The Range Rover MKIII (and I think LR4) has a 7700lb towing capacity, but a tongue weight rating of around 550lbs. You could easily get a Euro-caravan in the 7k range with a 500lb tongue if they center the axles right. Try finding one like that in the states? No way. 10% minimum, meaning 5k travel trailer tops. . If you have a slide, you are looking at 600~700lb tongue weight on a 5k trailer. Not a problem at all for my 2500HD (it loves it), but it sucks when I want to camp in one vehicle instead of having my wife drive behind the truck in the overlander.

You nailed a lot of good points 99Disco! Many of which I've tryied spreading among many forums.

A quick way to reduce tongue weight and / or lessen the rear GAWR is to move the heavy loads on the hitch to the rear of the trailer. Two 30 lbs propane tanks plus a deep cycle battery can easily weight 150 lbs. If you move that to the very back of the trailer, you free up nearly 300 lbs on the hitch due to the cantilever effect.

If that's still not enough, you can remove the 70 lbs spare tire, and toss it on the trailer, so that only 5 - 10% of that 70 lbs counts towards GVW or GAWR vs 100%. Doing the above two simple tricks can allow many large trailers to be safely towed by SUVs, as long as they're within GCWR.

Though I would recommend something like the Hensley Arrow if you decide to go near 5% tongue weight...

 

[ticklemenono]

WOW, Lots of great info. Thanks!

 

[ticklemenono]

WOW, Lots of great info. Thanks!