Optimal tongue-weight and wheelbase:length ratios?

[Pskhaat]

Are there any rules-of-thumb that based upon:

1. Net/Gross trailer weight
2. Total length

can describe

1. tongue-to-wheelbase, and thus
2. tongue weight?

Thanks,

 

[ntsqd]

The complex answer:
What I just posted here: http://www.expeditionportal.com/forum/showthread.php?t=18750

Have a look at the M.M. Smith books, particularly How to Design and Build Trailers — Vol. 1 & Trailers : How to Design and Build. Volume 2. Structure". There is an amazing amount of information on trailer design in these books.

The simple answer:
My Grandad had a simple formula, the (unladen) tongue should be 1/3 of the total length of the trailer. I inherited a trailer that he made from WWII 2.5t sideboards using this formula. It tows great from empty to over-loaded.

 

[Martyn]

Tongue weight should be 10-15% of the trailer weight to avoid trailer sway.

Going less than that produces sway even at slower speeds. Heavier than that and the trailer becomes difficult to move by hand and over burdens the vehicle rear suspension.

 

[opie]

I use a formula that hasnt failed me.

Locate the center of your axle, or equalizer if you are doing a tandem, 1" back from center for every foot of length.

I have a 5x12 tandem I built a couple years ago that I can move around by hand (albeit heavy), but handles fine at all speeds.

Then there is always the 60/40 split. If you have a 10' trailer, you will place your axle 1' behind center.

It also depends on how you are going to load it. The lastest trailer I built I put the axle right in the center. But Ive got the spare and a tool chest mounted on the front. So its got permanent weight on the tounge.