Ok I see that makes perfect sense. Weakest component tires/rims thus the reduced back axle carry of 6100 got it. Changing to tires and rims of a larger size and capacity is not an issue with me far cheaper then a new truck. That's why I ask questions you guys have been great.
The spring rate is your weakest link @ 6000 lbs. Tires are second but,
The certification label is the only acceptable weight rating as far as any state is concerned, legally. Therefore, legally the rating will be 6100#
The certification rating is the only acceptable form of legal weight measurement. That being so, there is no concern for other components with higher ratings. It will not be used in the axle load calculation, only what is shown on the certification label.
If you break a spring say doing 70 mph, crash and kill someone, or yourself, the DOT and local highway authority will be on that like glue.
If you could get Ford to increase your spring rate, which they dont offer in the 250. You have the max spring rate according to the link I posted. You would need to ask ford for a re-certification label to raise the GVWR and axle rates of the truck.
Or the DMV...