Tongue length calculation/formula?

[wADVr]

Does anyone know a formula or some sort of calculation to find the optimal tongue length? I see several builds or adv production trailers with extended tongues. I am building a m101A3 to follow behind my JKU. I have zero off road experience with this combo but can say in stock form this trailer tows quite nicely behind my JKU. Only complaint is not being able to straighten the trailer when backing up to turn around etc. it would seem an extended tongue would help with this but I want to keep the overall length down to a minimum. Any calculation or formula to take some of the guess work out of this modification?

Thanks,

 

[rnArmy]

At a minimum, you want the tongue long enough so the trailer, when attached to the tow vehicle, can be at a 90-degree angle sideways and nothing making contact. I call it "the 90-degree test".
So if you decide to add a cooler tray to the front of your trailer, the tongue may need to be lengthened to pass the 90-degree test.

 

[colorado matt]

i have heard many different things and wanting a formula like you I always check out the threads when this is discussed .... distance from the hitch to trailer tires should be same as wheel base of tow vehicle .... distance from back tire of tow vehicle to trailer tire should match wheel base of tow vehicle ... long enough to get trailer jackknifed without hitting .... long enough to open tailgate without hitting anything on trailer ..... for me the most "scientific sounding" is the first one ..... obvious one is not hitting anything when opening tailgate .... and the most practical one is being able to jackknife trailer 90 degrees without contact or binding ...... some even put extendable tongues on ... long for towing and backing and then shorten them up on more technical trails for better tracking ..... and while I have not started my build I will be going with a tongue that can be jackknifed without hitting and maybe just a bit longer than that because I have a tire swing out on my bumper that may push it a few inches past that .... I really like some of the extendable tongues but not sure my fab skills will allow it and wondered if it might be prone to rattles having more connections if you know what I mean .... Matt

 

[azscotts]

I didn't use any science behind it. But, I went with 48". When I add on the lock-n-roll hitch it should be closer to 55". The lock-n-roll receiver will add another 4"-5" so I'll be closer to 60" from the rear of my Tahoe when all is said and done. Overall length on my camper with the tongue will be right around 15'8" when hitched up.

Not sure if that is helpful or not.

 

[DanCooper]

This topic comes up frequently in this forum. Here is an article I found useful on the topic. I didn't write it, and I tested the conclusions aginst common sense, and I suggest you do that also. Hopefully it will give you some pointers.

 

[Nd4SpdSe]

As stated above, I also followed the guidelines and tried to keep the length of the coupler to center of the trailer wheels the same as that from the center of the front to the center of the rear wheels of the tow vehicle. Part of the design was a straight tongue and enough length to jack-knife and 90-degree pin the trailer. While honestly I will admit that I didn't think it was going to be that necessary to be able to get 90-degrees out of the trailer, I've actually found it handy and used it's ability to do that on many occasions for parking, camping and reversing.

 

[wADVr]

Anyone seen this calculator? Have any merit? You can use Inches instead of millimeters. Seemed interesting but maybe overboard?

http://toxiccelery.co.uk/Offtrack/The_Calculator.html


Thanks for the responses so far, I have read several threads but still feel it's guesswork. I can already jack the trailer 90° and beyond as well as open my tire carrier so I'm good there. I think it tracks so well due to the relatively short tongue/hitch to axle dimension(100"). Lengthening the tongue will cause the trailer to cut corners but will help with backing up without adjustment(pulling forward to restraighten) maybe it's a decision on which issue I can live with.

 

[wADVr]

Using specs for my JKU and my M101 in current state, the calculator link I posted above states my trailer will track 35" inside the radius of my jeeps rear wheel on a full circle. Not too bad, I don't think, it was interesting playing with the numbers. For example, lengthening the tongue 5" resulted in the trailer tracking 5" further inside from the jeep. Assuming this formula is correct. I might have to measure just to see.