Calculating degrees "off level"?

[frozebubba]

I know that "eyeballing" it will probably be close enough. But, it is nearly impossible to obtain a loaded hitch ball height of exactly 19" (or 21 5/8", lifted) for an Escape and I'm trying to calculate the number of degrees up/down because its raining and I have nothing better to do. You can use Rise Over Run to Degrees Calculator to calculate the degrees. The question is, what length do you use ? The advertised length of the trailer or the distance from between the dual wheels to the ball? My 2024 lifted 21C is advertised to be 21' 4" long (=256 inches) but the distance from between the dual axles to the ball is only ~169". For the full length, each 1 inch "off level" translates to 0.224 degrees. If you use the shorter axle center to ball length then each 1" off level translates to 0.339 degrees. Not much of a difference. Anyone out there with training in physics care to comment on the proper length to use for the "run"?

As an aside, I usually 1) eyeball it, then 2) use an IR heat gun to measure the tire temperatures after a good run. If you are low or high on the ball, the more heavily loaded tires (front or rear) will be warmer. Last fall, on a run from Fairbanks AK to Gainesville FL my old, un-lifted and fully loaded, 21C using a 4" drop ball carrier on a RAM 1500 4x4 would consistently run ~10F hotter on the tires on the front axle. I took a short (~200 mile) run with my new, lifted, 21C with the same truck but a only 2" drop on the ball carrier and the front and rear tires were very close to the same temperature. That makes me think the 2" drop works well for the lifted 21C.

Comments? Thanks!

 

[jjdeluca]

If the "rise" is the distance up (or down) from level at the hitch ball, you'd want to use the point at the axles for the "run" (169" in your case), since the mid-point of the axles is essentially your pivot point. This would be the simplest method.
If you used the total trailer length (256") as your "run", you'd need to take the distance up/down at the ball and add the distance down/up at the rear of your trailer to get the "rise".
Both methods should give the same result. Good luck!

 

[frozebubba]

If the "rise" is the distance up (or down) from level at the hitch ball, you'd want to use the point at the axles for the "run" (169" in your case), since the mid-point of the axles is essentially your pivot point. This would be the simplest method.
If you used the total trailer length (256") as your "run", you'd need to take the distance up/down at the ball and add the distance down/up at the rear of your trailer to get the "rise".
Both methods should give the same result. Good luck!

Thanks!

 

[Centex]

For that linked calculator you can use two measurements to ground at any points along the belly-band. Whatever the distance between the two points along the belly-band, that's the "run"; whatever the difference between the two measurements to ground, that's the "rise".

Increased "run" will result in proportionately increased "rise" which may make measuring small differences to the ground easier (when the slope is small). The calculator results will be absolutely accurate for whatever data you input.

It doesn't matter where along the belly-band you do this, it's a 'straight line', for practical purposes parallel to the floor / chassis of the trailer, which can be projected any distance to the front or rear of the trailer. No matter where the measurements are taken it'll yield the degrees of trailer slope with that calculator.

BTW, this isn't physics, it's trigonometry.

 

[frozebubba]

For that linked calculator you can use two measurements to ground at any points along the belly-band. Whatever the distance between the two points along the belly-band, that's the "run"; whatever the difference between the two measurements to ground, that's the "rise".

Increased "run" will result in proportionately increased "rise" which may make measuring small differences to the ground easier (when the slope is small). The calculator results will be absolutely accurate for whatever data you input.

It doesn't matter where along the belly-band you do this, it's a 'straight line', for practical purposes parallel to the floor / chassis of the trailer, which can be projected any distance to the front or rear of the trailer. No matter where the measurements are taken it'll yield the degrees of trailer slope with that calculator.

BTW, this isn't physics, it's trigonometry.

That would work! And I took trigonometry 60 years ago! Must have forgotten.

 

[Craig_TaB]

Gosh . . . what am I missing, this seems like a lot of over-kill for a simple Tow Ball Rise/Drop determination.

 

[Ron in BC]

because its raining and I have nothing better to do.

Gosh . . . what am I missing, this seems like a lot of over-kill for a simple Tow Ball Rise/Drop determination.

View attachment 871187

He answered that question in his first post.

I agree, it's not something that I've spent much time on. TLAR works for me.

Ron