Skip to main content

My trailer conversion / mod has taken longer than anticipated but is nearly done. I now need to figure vehicle position on the trailer to come out with a good tongue weight. The main brains indicate that a good tongue weight should be between 9 and 15 % of full load. For this method example, I'm using a known  empty weight of my Roadster of 1942 lbs and for calc method trials I'm guessing my empty trailer weighs 1500 lbs. I can verify that later and do final calcs from that number. 

Here's my plan and I could benefit from your input, please. Car and trailer weigh 3442 lbs. Shoot for 12% tongue load so that makes 413 lbs. I don't have heavy scales to measure the tongue weight but I can use bathroom scales which will easily take 1/2 of 413 so I plan to make a cross beam to hold the tongue up with the bathroom scale out  2' to one side and a wood block out 2' to the other side. I could then ease the Roadster up onto the trailer and move it forward till I see 206 lbs on the scale. 

Make sense ? Ideas ? Thanks. 

David Stroud

 '92 IM Roadster D 2.3 L Air Cooled

Ottawa, Canada


Original Post

The technique makes sense, but what is the tow vehicle?  Different tow vehicles work best with different tongue weights ( the tongue weight allowable is either on a door jamb sticker or in the owner’s manual).  I had to shift my speedster forward 4” on the trailer for a stiffer sprung F250 versus running it back farther for an F150.  Too far back and the trailer would wallow left and right above 35mph.  Too far forward and the truck’s rear end hung too low.  Happy medium gave a 3” drop on the rear bumper when loaded and no wallow. 

Percentage to tongue weight is just a ball park recommendation...try this : With the trailer hitched to the tow vehicle and not loaded  measure the tongue height. "Load the car on the trailer positioning it so the tongue is 1-1/2"  lower than first measured, secure and go for a ride and see how it feels , reposition forward or aft until you are satisfied with the steering and braking then mark that position on the trailer deck. Be sure to take into consideration extra cargo and passenger weight in the tow vehicle

Last edited by Alan Merklin

53557094-F973-4AD8-866F-6B1C5A3B2C99You are over thinking this.

The trailer is so light and so is the car that you will undoubtedly be within any maximums. But given your weight estimates, the 10% rule should be applied. Your 3500# weight should have roughly a 350 lb tongue weight. A homemade(?) trailer may have a bad balance vs a production made trailer. Better to be tongue heavy than tail heavy (makes for tail wag or sway). Also measure your truck sag before & after- it shouldn't sag excessively.

Hopefully you are using a tandem axle trailer... Balance your lightweight car with the motor/transaxle just behind the axle (s) and the rest forward. Do as Gordon says and adjust so your trailer does not wag back and forth. More importantly is having electric brakes for your weight, AND, having a steady & smooth driving style. Any trailer can be pulled poorly.

My current setup, balanced as described... (apprx 5K combined)



Images (1)
  • 53557094-F973-4AD8-866F-6B1C5A3B2C99

As Stan says get a little tongue weight. Trailers like that. 

Don't ask me about the time my 20-year-old switched my receiver from the 2 5/16 ball down to the 2". Hooked up to the enclosed car trailer (full) in the dark. Didn't notice until it came off at 65 mph. Quite an experience. Seeing the damn thing fish tailing behind the F150 -up on two wheels one side then the other. Kinda wished I had a piece of coal in my backside -would've had a diamond by the time I came to a full stop. 

Add Reply

Post Content
Link copied to your clipboard.