Placing Axle on BBQ Smoker Build

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I have built a few med size smokers (250 gal) on trailers, but want to ask a question to see if I can help the set up on the trailer faster.  I have the back of the trailer at the end of the 250 gal tank and have the fire box extend past the end.  I aware of the 60/40 rule on placing the axle on trailers, but this would make my smoker to light in the front.My question: do I use the 60/40 rule from the front of the trailer to end of trailer (B) or the end of the fire box (A) or still make the first measurement using the trailer front and end and make the adjustment to add weight to the front (move the axle back some).Any help is very much appreciated.thanks Attached Images
Reply:I place the smoker/trailer minus the undercarraige (springs and axle) on a fulcrum. I then move the fulcrum till I have the tongue weight I want.  The last trailer smoker I built I used a 500 lb tongue weight.  This allowed the man to load some wood in his fire box at the back of the trailer without causing driving issues.
Reply:Originally Posted by Scott YoungI place the smoker/trailer minus the undercarraige (springs and axle) on a fulcrum. I then move the fulcrum till I have the tongue weight I want.  The last trailer smoker I built I used a 500 lb tongue weight.  This allowed the man to load some wood in his fire box at the back of the trailer without causing driving issues.
Reply:The cooker had a 3 foot fire box, 8 foot cook bed, and 2 foot by 3 foot by 6 foot smoker, all with propane assist.  The backside of the cooker had 3 propane hot spots and two double basket deep fryers.  At the tongue of the trailer was 2-propane tanks and 2 water tanks both with optional heat.Some features of the cook bed.  It was double layered.  It was divided into two 4 foot sections.  one section had a griddle top and the other a grill top.  The griddle top was removable so the full 8 foot could be used as a grill top or smoker.  It could generate some smoke and with the propane assist the temps were very even.
Reply:Originally Posted by Scott YoungThe cooker had a 3 foot fire box, 8 foot cook bed, and 2 foot by 3 foot by 6 foot smoker, all with propane assist.  The backside of the cooker had 3 propane hot spots and two double basket deep fryers.  At the tongue of the trailer was 2-propane tanks and 2 water tanks both with optional heat.Some features of the cook bed.  It was double layered.  It was divided into two 4 foot sections.  one section had a griddle top and the other a grill top.  The griddle top was removable so the full 8 foot could be used as a grill top or smoker.  It could generate some smoke and with the propane assist the temps were very even.
Reply:The standard rule for trailers, as far as I know, is to put 12 to 15 percent of the trailer weight on the tongue.I like the idea of putting the unit on a fulcrum, finding the balance point, and then moving the axle back from there.   That gives you a firm place to start.It turns out that you don't need to know the trailer weight to get a given percentage of the weight on the tongue.   You start with the balance point, then measure the distance to the hitch ball.  Let's call that L.W is the total weight of the trailer, T is the tongue weight, M distance between the balance point and the axle.   T = W * M / (L+M)Transforming that equation into a more useful form, you getT/W = M/ (L+M)T/W is the percentage of the total trailer weight that is on the Tongue.  Let's assume you want 12 percent on the tongue.   Let's assume the distance from the balance point to the hitch ball is 10 feet.If we move the axle back one foot from the balance point,M/(L+M) is 1 / (10+1) = 0.0909, or around 9%, not enough.If we move the axle back 1.5 feet from the balance point,1.5/ (10+1.5) = 13%, very close to the 12% that we wanted.I could draw you a vector diagram if you want to see it, but I am pretty sure that I have the math correct.One thing you need to consider is whatever you load into the trailer, such as firewood.  Ideally, you would check the balance point of a loaded trailer, but that may be impractical.RichardSculptures in copper and other metalshttp://www.fergusonsculpture.comSyncrowave 200 Millermatic 211Readywelder spoolgunHypertherm 600 plasma cutterThermal Arc GMS300 Victor OA torchHomemade Blacksmith propane forge
Reply:This is why I like to ask you guys these questions.   Thanks for the help.
Reply:Beware of the standard rules of having 12 to 15% tounge weight or the 60-40 rule. The ratings of the tow vehicle and hitch must be considered. Most pickups with even a 10,000# tow rating will only have a 500-600# tounge weight rating.With the standard rules a 5,000# trailer would have a 750# tounge weight.