Just to clear up some misconceptions about tire sizes, the main difference between a 60 and a 75 is going to be the overall diameter and sidewall height. The tread width will be pretty close to the same. The main difference in the steering effort is going to be in the lower rolling resistance of the taller tire. The 60 series tire will ride harsher, and have a lower load capacity.
As to the original question, the 235/75/15 will be fine on that wheel, it was an oem tire option on the Blazer and Trucks with those wheels, though most did have the 10.00-15 or 31x10.50x15 tire option, depending on year. I'm running them on my '55 2nd, stock axle/brakes/steering, with 30x9.50x15s on them. Steers just fine if the truck is rolling. It's only really hard to steer if the truck is stopped.
