Why is a 5th wheel.....called a 5th wheel??

[Deezal Man]

One of my buddies, who's automotive ability is limited to turning the key and driving.

Asked what a fifth wheel was, and why it was called that. Naturally I could explain what it was and how it worked, but I didn't know where it got its name.

Anybody know??

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98. 5' 24v 2500 Auto/3. 54 4x4 SB QC 285-75-16's on Alcoa's. Everything but leather. PIAA 1200's, AMSOIL dual filter relocation system, Smittybuilt Stainless Steel Nerfs, Rhino Liner(Junk), K&N air filter(For Sale)15 year AMSOIL dealer. Time permitting, Soon to include Ultra-lite Pyro,0-50lbs boost, Trans temp in the pillar. Rancho 9000's with in cab adjustment.

 

[Okie-Go]

I would say that with the four wheels on the ground and the hitch it touches in 5 places. Thus the fifth wheel. Don't know for sure but it makes sense.

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2001 quadcab slt 2500 HO 6spd. LWB,2wd,dk garnett red, trailer tow package,camper special, anti spin 3. 54 axle, speed liner,oversized stainless steel chicken slide,66 gallon in bed aux. tank,K&N air filter,Reese 20k hitch, Terry 2000 EX 30ft. double slide 5er, 2000 20ft gooseneck for haulin jeep, firewood and huntin stuff. 5X12 tagalong for haulin the 4 wheeler. Okie Newton

 

[wbrown02]

The term comes from the trucking industry as on a big rig the hitch is almost as big as one of the road wheels. Drivers started calling the hitch that looked like a large wheel the 5th weel. Very simple.

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95 Ram 3500 Reg Cab Dually,5 speed, 3. 54 Dana 80, Gear Vendor,TST 235/605, Jannetty 4"exhaust,Psycoty K&N 880,Prime Loc, Pac Brake,Valentine One, Full Gauges..... ect... . ect