changing wheel size and overdrive unit.

[Hank Jourdin]

need some help, has anyone changed from 16.5 x 6  dually wheels to anything
besides 16.0 x 6 wheels? has anyone gone to a 17.0 x 6 , 6.5, 6.75 or 7 wheels
If so what size wheels and tires are being used ? I am a new member and I am
restoring a 1978 21ft  American clipper with a 440 . I am making some changes
to the motor and transmission as well as wheel and tire size to improve gas milage. I want to use the tallest tire possible having a 4.10 axle gear.I will be using a gear vendors overdive unit which will actually splits gears turning the 727 torqueflite 3 speed into a 6 speed .you can underdrive or overdrive every gear. I can't wait to see the results. If you take what ever r.p.m. the motor is
turning at a given speed say  3500 r.p.m. in high gear it will only be turning 2,730 r.p.m. at the same speed  ( example 3500 x .78 = 2,730 ) thats 770 r.p.m. less , and for every inch in tire higth the rpms drop 100 rpms = fuel mileage I an looking a a set off  17" x 6j" aluminum dodge 3500 dually wheels and I don't know what the j stands for . I would be very grateful for any positive input any of you members might have , I have read all the  teck reports
that came with my clipper and enjoyed all the problems and all the answers
oh the dually wheels say 1994 to 2008   maybe?

[JerryT]

Hank
I have a Gear Vendors installed in my 78 rear kitchen 440. I did it myself with the help of my best friend who is a 25+ year transmission rebuilder/installer---or maybe I helped him
I have also given much thought to a wheel/tire change---but I stayed with the 16.5s in the 8.75 flavor which is an upsize from the stock 8.00s
I have re-sprung the rear and also had new/larger (more#s) coil springs installed up front as the 8.75s would rub from time to time.
I do not think a larger tire/wheel combo would fit
The 1978 Clippers have "coined" 16.5 wheels.
Dodge one ton trucks built in the 80s and up to 93 had 16" "coined wheels.
The cost of the 16" wheels vs the savings of not buying 16.5 tires was not there for me.
The burden of finding 7, 16" coined one ton dodge wheels that ran true (not bent) could be costly
I measured my buddy's 93 D350 tire/wheel size and concluded it was too large for the CB300s (clipper chassis)
I love my OD, it puts the motors torque range in at about 75 mph with it on.
I still need to be in direct drive on long hills/steep grades.
I can give you some install ideas if you want.
This is getting long, if you want to talk on the phone just let me know.
JerryT