hi all, i a was looking to see if anyone out there has measurements they could help me with. i want to know approx. how high my tailgate would be when opened, if i put on a 6" lift and run 37's. i am trying to see how much i will need to lengthen my dirt bike ramp so loading it wont be a scare. right now it is just under 6' long, and at the stock height its real easy. thanks for your help !!!

 

What size tires are you running now and are you at stock height right now? I would imagine you could add 6" plus the difference in wheel and tire radius (diameter divided by 2)...which would get you pretty close. Each lift can sit a little different..for example a DR 6" may be a little larger than lets say a pro-comp..due to the springs.

 

Don't forget...that 6" lift is only 6" in the front of the truck. Typically on a "six inch" lift it's gonna be 6" in the front and about 4.5" in the rear... I think. This is because for whatever reason most / some lifts result in a level truck instead of the nose down stance that they have from the factory.

Does any of this make sense?

 

You will use the Pythagorean's Theorem ( A squared + B squared = C squared) to calculate the new ramp length.

A= the distance from the ground to the tailgate
B= the horizontal distance from the tailgate to the end of the ramp
C= the length of the ramp

The angle, delta, of the ramp equals: tangent of the angle = A divided by B

Assuming your truck is the same as mine( ‘04 4x4 CC LB F350 Camper package), the distance from the ground to my lowered tailgate is 37 inches. I calculate the angle of your ramp with the ground to be 30.92 degrees using the following:

The square root of (BxB)=(72 x 72)-(37x37)
The square root of (BxB)=5,184-1,369
The square root of (BxB)=3,815
B=61.77

Angle calculations: A/B=tangent delta= 37/61.77
Tangent delta = .5989962
delta = inverse tangent x .5989962
delta = 30.92 degrees

Okay...assuming 6" of lift at the back, the new ramp length shall be: (37+6) divided by B = tangent of 30.92
43 divided by B = .5989962
43 = .5989962 x B
B = 43 divided by .5989962
B = 71.79 inches

The new ramp length, x, equals: 43 squared + 71.79 squared = x squared
1,849 + 5,153.8 = x squared
x squared = 7,002.8

The new ramp length, x, = 83.68 inches

If a 6" lift only raises the rear 4.5 inches (for 6" lift), the new ramp length should be 80.76 inches.

You can also equate this to a ratio of height of tailgate divided by ramp length equals .5138. New ramp length would be height divided by .5138.

This means you would divide the new height off the ground of the tailgate by .5138. i.e. 37/.5138 = 72 inches, 41.5/.5138 = 80.76, 43/.5138 = 83.68 and so forth...

 

yea what he said

 

wow beemr......... thats something.... you lost me at the first calculation, lol !!! well, thanks for your help guys. i may just keep it the same, and look cooler as i load it !!

 

Your math is good, but you forgot he wantd 6" lift plus 37's...

An easier way (for me anyway) is just to figure how much "bigger" your triangle's getting.

37" stock height, plus 6" lift, plus about 3" tire (from 31" stock to the 37's) means your load height's going from 37" to 46" -- an increase of 24.3%, which we'll just call a quarter.

Lengthen your ramp by the same quarter, from 6' to 7'6" and you should be golden.

Robert

 

I stated that way, also...that's why I also listed the ratio of height of tailgate to length of ramp...

It is much easier for the layman to use that than all the math crap I spit out.

 

yeah, but your way was so much prettier...

Robert

 

That method is called "The Theorem of Similar Triangles (or shapes)"

 

Nooooo....
It would be 97 inches at an angle of 28 degrees.
If you have a tailgate liner add 2 degrees of angle.

 

That sounds about right.

However, based on my stock F350, you have lessened the angle of the ramp slightly (which makes it easier to load). The distance to the tailgate from the ground stock is 37 1/2". With a 6' ramp, this gives you an angle 31.39 degrees, instead of the 28 you refered to. A 97" ramp @ 28 degrees would give you a new tailgate height of 45.54 inches.

If you have an F250, the original angle should be 29.54 degrees, again based on my truck, due to the truck originally being 2 inches shorter in height than the F350.

 

Yes, but you didn't compensate for summer air in the tires, you used winter air in your calculations.
And you'll have to remember, for every 6.4 degree increase in angle you'll get a 46.3% increase in pucker factor.

Sheesh, you guys!

 

True, true.......

....but here in Houston, Texas, our winters only last 1 day!

 

Holy I thought my gear ratio formula confused folks.