First time I ever weigh my rig. Pulling a 32' HR FW. Front axle 4,300 lbs; rear axle 5,800 lbs.; trailer axle 8,900 lbs. For you towing experts; how much does my trailer weigh?? I don't know how much the rear axle weight is on a: 2006; SW 2500 Big Horn with 48 RE trans and [CD]diesel so I can't do the math for the trailer weight.
PS - folks at Love's here in Chandler,AZ; were REAL nice coming out in the 110 degrees weather to show me what to do. Come in with me little FW and there's a BILLION big rigs buzzing all around me. Yes; somewhat intimidating.

 

My drive axle was #2880, front axle was #4300. Pretty much empty had (3) 7 yr olds in the cab at the time. I was on my way to pick up the boat and wanted a base number. With the boat trailer on, the front axle went down to #4100 and drive went up to #3540 and trailer axle was #5680. So tongue weight is #660 lbs and total trailer is #6340. FYI

 

I calculate your tonque weight to be around 460 lbs.

 

Don't you just take the added weight as the tongue weight? The downward force on the hitch forces the front up a little, but didn't think that weight is deducted from the tongue. So my rear axle went weight difference is 3540-2880=660 lbs.

So markpp ( using my numbers) has a tongue weight of 2920 lbs and total trailer weight is 11820 lbs and about 24% of the tongue is on the truck. here are my numbers, let me know if I'm off track. 5800-2880=2920 lbs tongue. 8900+2920=11820 (lbs total trailer) and then for % weight on truck 2920/11820=24.7%. I believe this is correct.

 

You could do a free body diagram for each axle measuring the distance between each and where the tongue sits with respect to each, but that's the long way (but accurate).

Simple quick way is this. All the weight must add up. Before: the truck weight (add up both axles) is 4300 + 2880 = 7180. After: the truck and trailer weight (add up all three axles) is 4100 + 3540 + 5680 = 13320. Since weight can't just disappear (neglecting loss or gain from fuel) the trailer weight is total weight after - total weight before...... 13320 - 7180 = 6140. But - the trailer is being held/supported by two locations: tongue and axle so if the axle sees 5680 then the tongue must be 6140 - 5680 = 460.

Sound right?????

 

For Markpp.....a fifth or gooseneck trailer hitch should theoretically be directly over the rear axle. Any added tongue weight could again theoretically be extracted from the before and after rear axle weight. This can be confirmed (if they have identical trucks) by the before and after front axle weight. They are the same. So the estimated trailer weight would be 8900 + (5800 - 2880) = 11820 ---- same as what Fox has!

This is not the case with a bumper pulled trailer as you are cantilevering the ball/hitch over the rear axle thus the reason why the front axle is less after hooking up a trailer.

 

Thats interesting NDanecker, I have wondered about the weight and the cantilevering part on the rear end of my TT. Since the general rule is 10% of trailer weight should be on the tongue should I position the boat a little closer to the truck get the tongue around 600 lbs? The axle weight would increase to #3740 or so but that is no big deal. The setup handles nice on the road but do notice a slight oversteer if the boat is full of gas. The boat has a 75 gallon tank and the tank position relative to the tandom axle is slightly aft. It's not a big deal since I really don't like pulling around the extra fuel . But now that it's fresh in my mind, which is more critical the rear axle weight, the straight tongue or just kind of fudge between the two. Being only around #200 difference it is not a biggie but I would like to do it right.

 

MY truck weight is 9.760 this is with 100gal fuel tank with 30gal fuel extra tire and tool box-With trailer on F axle 5.160-Both with trailer 12.160 Truck@ trailer 22.900 we will put about one more 1.000 pounds in trailer before we Lev the trailer weight hooked up is 10.880 The trailer is a fifth wheel 38ft