I ran that size tires on my 59 Suburban, with 3.40 gears in the rear end (79 Blazer rear axle) with an SM465 trans an loved it. I could cruise along at 90 if I wanted to and it pulled whatever I put behind it (broulght my bog bolts home, weighed in at 17,340 with the 59 behind it). That said, depending on how you are using it, and with the 235 , your 3.90 gears should be great!
sorry its been awhile. you are correct Mike B. I'm changing out the 3 speed for a 4 speed. the trans in it has a 2.85 first gear. I'm thinking a taller first gear in a 4 speed would be better? I would like to drive down the highway without overdoing it RPM wise- 2200 to 2500 RPMS. thanks
According to the 1959 truck resto pack your truck rear end had a Regular Production Option RPO 3.70 and 3.38 You could find a 3.38 ring & pinion 3rd member and install in the axle housing and you could drive at 70-80 mph all day long. The Resto pack does not seem to show the RPO number for the 3.38 RPO, Teeth 13-44