5th Wheel Trailer Hitch and Install Kit for 2012 Toyota Tundra Short Bed and Clearance Measurements

Question:

Is it possible to mathematically determine if a 5th wheel will hit the cab of the Tundra. I dont know how much slide I need with a 6 1/2foot bed and it seems logical to nail down which 5th wheel we want before deciding on the hitch. Assuming the pin is in the center of the front of the 5th wheel, would half of the width measurement from a point directly over the rear axle give an accurate swing required? Also if the pin weight is around 1,500 lbs and the GCVW is under 15,000 lbs., should I be looking at a 15K or a 16K hitch?

asked by: Phil R

Expert Reply:

Yes, you can mathematically determine clearance for turning while towing a 5th wheel trailer. There are several measurements needed.

1) Distance from the back of the truck cab to the center of where the king pin will be when coupled
2) Distance from center of king pin to front of trailer overhang
3) Overall width of the front of the trailer

So for example if measurement 1 is 30 inches and the king pin is 10 inches in front of the trailer that adds up to 40 inches. If you then used a slider hitch with 12 inches of travel the total would be 52 inches.

Let's then say for measurement 3 the width is 92 inches. You divide that by 2 to get half; 46. In order to safely make 90 degree turns without hitting the trailer into the truck the clearance measurement, 52 in this scenario, has to be at least 4 inches MORE than half the width of the trailer (46). So in the above scenario it would work great.

On your truck, the centerline of the hitch will be approximately 1-3/4 inches forward of the center of the rear axle. Measure from that point forward to the back of the truck cab to get your first measurement. Then add (or subtract) from it the distance from the king pin center to front of trailer. If the king pin is out in front you add it in but if the king pin is recessed under the trailer you subtract it.

Then you would add to that the amount of travel from a slider hitch. I recommend the hitch with the most travel which is the Demco HiJacker, # DM8550034, which offers 14 inches of travel and slides automatically and it fits industry standard above the bed rails!

The only thing left is to determine half the width of the trailer.

For an installation kit I recommend going with a custom kit, # RP50084-58, because you won't have to drill into the truck frame for installation. Regarding the hitch it is better to have a hitch that exceeds the capacity of the trailer for safety and so it is easier on the hitch which also helps it last longer. The recommend HiJacker is rated for 18,000 pounds so it will be perfect for a 15K trailer.