Ive got a couple projects I need to finish up. Ive been screwing around with this one for 6 months. New year coming up and Im going to get one project done each month in 2014.

My 66 long bed 352/3 spd with 3.25 gears and a 28.3 in tall tire runs at 2700 rpm @ 70 mph.

I want to lower rpm.

I have a 2.75 gear set I pulled out of a 76 rear end sitting on the garage floor. That would lower rpms to 2286 @ 70 mph.

Keeping the 3.25s and going to a 31-1050-15 lowers rpms to 2532.

Keeping the 3.25s and going to a 33-1050-15 lowers rpms to 2338.

Will a 33-10-50-15 on an 8 in rim fit under the rear wheel well on a styleside?

If I install the 2.75 gearset I will run 235/75R-15 all the way around. That gives me 2239 rpm @ 70 mph. Gutless if I need to pass Im sure.

 

i know for a fact i ran some bfg 33x12.50 15s on my 66 f100 and the only time they would rub was when i was sliding corners because my bushings on my leaf springs were shot

 

i would go with the 2.75-78 gears with the 31s and then you have the best of both worlds.... and when you need to pass that's what your next gear down is for silly lol

 

The 2.75s do suck on take off, but once you get some R's rolling the power comes back. You will get to pass one more gas pump.


John