We would need to know what rim size you have on that truck. 16" or 17"? If you are running a 16" rim, you can fit either a 235/85R16 or 265/75/R16 with no ill effects, aside from loss of acceleration, maybe some ride quality depending on what load range tire you get. Interestingly enough, my speedometer became spot on accurate when I went up to 235/85R16's from the stock 245/70R16's that were on my truck.
You can fit a 255/85R16 on the stock truck but you will get rubbing...
For more info, the 235's are tall and narrow. Really good in mud and slushy snow, they cut through it instead of staying on top of it. In rain and on dirt roads, I find the narrower profile to have less grip. The 265's are really fine in all conditions and the main difference is the 235's weigh less, tend to be cheaper and are slightly taller. I've had both sizes on my trucks in the last 3 years and the 265's are a much better all around tire in my opinion. When I could get the 265's for the same price as the 235's I did it. But I usually go for the cheaper/lighter tire on my 4cylinder truck.
Cheers,
Jorge