[glamis_dave]

ok anyone who knows me knows that it's not allways easy understanding what im trying to type...and this one has alot of info to crunch to anser i think...info first..stock everything except for the dp chip and 4 in exhaust,6 in lift,315/75/16 tires,buggy rack on top of truck,12,000 lb trailer,21,000 gross combined...future mods...big oil,tn bb,fuel system...backround info....towes just ok..had smaller 285/75/16 tires and it towed way better,but looked really gay,and dont want to be running 2800 rpms at 75 mph...question been looking for the sweet spot,for about a year,want it to tow like it had the smaller tires,and hot rod when empty,truth be known the tires seem to tall even un loaded,perhaps i expect to much,i dont want a gear vender,i want the perfect combination of engine mods-power and gearing for my high in the air,fat tires,no airodynamics,heavyload,trying to pull the hitch off tow truck.....ps i dont want a vender cause they dont make one that will handel the weight and power.that i have ever heard of....david

 

[glamis_dave]

oh crap this is the wrong forum isnt it.....

 

[mattymx]

My friend has nearly the same rig as you do. But he is running 37's. He changed to 4.56 gears and he has a towing beast. He can haul his 37ft toy box really well. I would point you in the route of 4.30 as a minimum or 4.56's. I think 4.30's will be a better gear for you and your weight.

 

[glamis_dave]

4.10 isnt enoughf

 

[glamis_dave]

and wont the big oil,turbo anf fuel system overcome some of the gearing...

 

[mattymx]

My friend went from 4.10's to the 4.56's. With the 35's you are running with your 3.73's, it would put you near stock overall gearing. The 4.30's will put you just a tad lower for better towing while not killing you while empty. At first my friend had 35's when he first installed the 4.56's and said he could tow his rig with no issues. Now with his 37's he feels he has the perfect combo. I think the 4.30's would be the right match. hope some others will chime in with their opinions and experiences.

 

[mattymx]

and wont the big oil,turbo anf fuel system overcome some of the gearing...

that will give you better running all around, but the right gears are what makes a good combo the most efficient. With the right gears you will be in the meat of the powerband when you need it and will lessen the load on the engine so it can run to its peak.

 

[DART505]

I run 3.73 with 35" tires no problem & going to 3.55 with a 33' tire in my other Super Duty.