Originally Posted by JIMNLIN
Probably true with the older trucks but not with some of the new trucks with the high GVWR numbers. Looking at Rams body builders guide shows several trucks that may exceed its RAWR when using a GVWR based payload.
Example is a 2500 Ram 6.4 Hemi 10k GVWR with a 6k RAWR with a 3610 lb payload..
These trucks can weigh in the 3000 lb range on the rear axle. Now add a 3610 lb payload in the bed = 6610 lb load on the rear axle. Thats a 610 lb overload.
Okay, I concede. I admit that I used a poor example to relay the message I wanted to communicate.
Allow me to get it right. Letís get back to the GCWR and GVWR and the calculations that SAE J2087 uses to prevent the TWR from exceeding the GVWR or the GCWR.
BTW: If you havenít done so, I recommend you read question one on the FAQ page at the RV Tow Check website.
Use this real truck as an example from Ramís chart.
2016 Ram 2500, Crew cab, Short box, 4X2, 6.4 Hemi
Ft. GAWR: 5,500
Rr. GAWR: 6,000
Base Wt: 6,389
Base Ft. Axle Wt: 3,584
Base Rr. Axle Wt: 2,805
The formula that J2807 uses for GVWR in conjunction for calculating 5th Wheel TWR is (GVWR-TVTW)X5. The X5 is for calculating pin weight at 20%.
TVTW = (6,389+100+70+300) (Base Wt. + Cargo + Gooseneck hitch + Two people) This is the Ram standard for J2807 on this chart.
(10,000-6,859) X5= 15,705
In the above equation, the available payload (3,134) is multiplied by 5. As far as the rear GAWR, it will not be exceeded here. (3,134+2,805= 5,939)
Per your example (2,805+3,610), the rear GAWR would be exceeded by 415 pounds. The problem is, your example is not realistic because the published payload does not include any passengers, cargo and hitch weight.
J2807 has a second formula that must be used, and in between these two formulas, the least TWR must be used.
The second formula is GCWR-TVTW=TWR
Therefore, between the two calculations, the least TWR that will be used is 12,941. (One pound more than the chart due to fractional numbers being rounded.)
RV Tow Check (RVTC) uses the same formulas as required by SAE J2807. Assuming that you noticed, RVTC uses the respected multiplier for the full range of 10% to 25% for 5th wheel and conventional pin/tongue weights. Additionally, RVTC allows users to enter realistic passenger, cargo and hitch weight to obtain realistic vehicle towing capacity (a.k.a, realistic TRW).