Towing Question - Lets talk RPM\'s, Tire sizes and gear ratios I am trying to figure out which tranny will offer me the best towing for my rig. I recently bought a 18' camper with 2800 pound dry weight. GVWR of the trailer is 4000 pounds. I am going to install an auto tranny in my rig when I do the WMS Dual Case swap. I would like to try to tow this trailer by installing some "skinnies" on the truck to lower the truck. I will be using a load distributing hitch setup and probably a sway control. I have done some number crunching and would like to find out if I should use a TH350 or 700R4 for my application. I used the formula to figure MPH, then factored out the RPM's by giving a constant 65 MPH. Here are my numbers: TH350 - 3213 RPM with 31" tires 700R4 - 2249 RPM with 31" tires TH350 - 3018 RPM with 33" tires 700R4 - 2113 RPM with 33" tires TH350 - 2845 RPM with 35" tires 700R4 - 1992 RPM with 35" tires These figures are with the 700R4 in overdrive and the TH350 in drive. Which would be a good RPM range for pulling this trailer? Give me some input. Thanks.