The 60/40 layout...

[TinKicker]

Tell me, how did the 60/40 rule come to be sort of defacto? What, exactly, are the negative aspects of 50/50 or other percentages? I know, of course, that the further back the axle is, the more weight is on the tongue, which is limited. How, though, did 60/40 come to be sort of ideal?
I know I learned all this at some point in my life, but I'd kinda' just like to get the gist of it to get me beyond trying to build something otherwise and end up with the doors in the wrong place or something equally disastrous.

[Kevin A]

Tell me, how did the 60/40 rule come to be sort of defacto? What, exactly, are the negative aspects of 50/50 or other percentages? I know, of course, that the further back the axle is, the more weight is on the tongue, which is limited. How, though, did 60/40 come to be sort of ideal?
I know I learned all this at some point in my life, but I'd kinda' just like to get the gist of it to get me beyond trying to build something otherwise and end up with the doors in the wrong place or something equally disastrous.

Kelsey,

It mostly has to do with having enough room for the fender and a door on such a small trailer. Of course you could build one like this one:

[TinKicker]

Kevin, thanks for that simple answer. Yes, I know proportions are very important. I just didn't really know if it was something learned the hard way, like "back in '92 I built my tear 80/20 and it broke in half on the turnpike at 80 miles an hour" or something.
Yeah, I could see me crawling in and out of that little door. That fender would look like crumpled newspaper from my butt and knees beating it down. Must be some wee little folks going into that one.

[Dean_A]

Another reason is that for many (most?) tears, much of the weight is in the rear (galley, ice chest, cast iron, stoves, batteries, etc., and the front is mostly empty. With a 50/50 split, you could end up with a negative tongue weight. Of course, this doesn't apply if you have a tongue box loaded up with gear/batteries.

[Nitetimes]

The 60/40 thing is pretty much a standard for all trailers below semi trailers. It gives you a good tongue to load weight. With your trailer at 50/50 you basically have no tongue weight and your trailer tends to flail around unpredictably.

[angib]

Yep, if you have the wheels further forward than 60/40 you will get a light tongue weight and that means trailer sway will start at a lower speed.

Here in Yurp we do run lighter trailer tongue weights, but you don't want to become Yurpeen, do you? Like being French - that sorta Yurpeen?

Andrew

[Billy Onions]

Nitetimes is right,

it is the same genreral rule for most flat bed trailers not just teardrops.

[Alphacarina]

The 60/40 thing is pretty much a standard for all trailers below semi trailers. It gives you a good tongue to load weight

Yet when you buy most prefab trailers or the HF trailer kits, you do have to relocate the axle rearward to achieve a 60/40 split - They don't come that way. I have a couple small commercially built trailers which came with the axle right in the center. Empty, they still have positive tongue weight because the tongue end is heavier than the tail end and when loaded properly, they have even more tongue weight

I suspect the '60/40 rule' is probably a carryover from early teardrops which were loaded more heavily in the rear and then also because of the door location issue - Nowdays I think we just stick with it because it looks cool

If you intend to go with a tongue box for batteries/generator/gear then 50/50 makes way more sense, especially if you're towing with a small car. With 60/40 and a heavy tongue box, you could wind up with way more weight on the car than you want . . . . certainly way more than the 10 to 15% of the loaded trailer weight which is considered ideal

Don

[Arne]

while the bulk of the heavy stuff is at the back, the bulk of the body weight is at the front......

60/40 puts the axle 'about' where it belongs.....

[brian_bp]

"About" is definitely the key here. If the mass of the trailer and its contents were evenly distributed along the body length, then some specific split of that distance would yield a reasonable tongue weight (still depending on the tongue weight)... but nothing other than maybe a cargo trailer is loaded that way.

The important items are the fraction of the weight on the hitch (tongue weight), and how widely distributed the mass is (tighter grouping means less rotational moment of inertia, which is better for control).

I would ignore the "60/40" (or any other numbers) rule-of-thumb and use a planning tool such as the Trailer Balance worksheet (in the T&TTT Design Library) to get the tongue weight reasonable.

[TinKicker]

I would ignore the "60/40" (or any other numbers) rule-of-thumb and use a planning tool such as the Trailer Balance worksheet (in the T&TTT Design Library) to get the tongue weight reasonable.

My very next thought. How did you guess?

[Arne]

I found coming up with the weights to use the balance sheet difficult. I 'kind of' used the 60/40... actually, I eye-balled it.... looks good bolt it on temporarily.... then I just lucked out.... it was within a couple of inches of being 'perfect', so there it stayed... wound up with 10% of the weight on the tongue..... can't do much better than that.

[angib]

I found coming up with the weights to use the balance sheet difficult.

I agree - that's why I added the 'rule of thumb' percentages to the trailer balance page.

I think using percentages is better than nothing, but if building an oddball design (eg, heavy galley or heavy tongue box), it may not be good enough.

Andrew

[Billy Onions]

I think a lot of it comes down to common sense. As pointed out the uneven weight distribution of a teardrop is almost impossible to apply any one scientific rule to.


However, what I have noticed is that a lot of speed boat trailers have their wheels further back than most general purpose trailers appear to. Could this be because of the majority of them have the bulk of their weight at the rear? Very probably.

I also read somewhere recently that the nose weight should be around 4% of the gross trailer weight. So a half ton trailer should have a nose weight of around 45 pound? Seems very light to me.

I would check your vehicle manual and try and get it somewhere near but not worry too much about being bang on.

Anyone who has a cycle rack that bolts to their towbar will tell you that depending on whether you have one or 3 bikes on the rack your nose weight could be anything between 100 - 160 pounds. I doubt they notice much difference whilst driving.

[angib]

what I have noticed is that a lot of speed boat trailers have their wheels further back than most general purpose trailers appear to. Could this be because of the majority of them have the bulk of their weight at the rear?

Yep, that heavy outboard hanging off the back means most speedboats' centres of gravity are no more than 1/3rd of the boat's length from the back. so the trailer wheels have to be a long way back to compensate for this.

I also read somewhere recently that the nose weight should be around 4% of the gross trailer weight. So a half ton trailer should have a nose weight of around 45 pound? Seems very light to me.

Beware - you are quoting European numbers on a (mostly) American site and you may get shot down in flames. European and American towing practice are fundamentally different and the two places set up trailers differently as a result. Briefly:

A hitch weight of 4-7% of total trailer weight is the recommended range for caravans in Europe. These will be driven not much over 60mph, if at all, and the driver will be always aware of the possibility of sway or snaking starting. The trailer may be up to 100% of the tow vehicle's weight.

A hitch weight of 8-15% of total trailer weight is the recommended range for trailers in America. These may be driven at speeds over 70mph and the driver will expect that the trailer will look after itself. The trailer is likely to be less than half the tow vehicles weight, except for big trucks set up for towing.

Andrew