THen your truck may have come in slightly lighter than std specs. I personally would use the actual wt left after adding in people etc for figuring out max HW, then from there gcwr less tare equal max trailer to gcwr. Then compare the MTW using payload remaining divided by HW, and MTW with gcwr less tare, The lower number is the max total trailer you can tow for that day in time etc per say.
There is not a simple formula that will give you the MTW ALL the time. One needs to compare more than one number derived from more than one source.
Marty
