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!
