Question for ya.. What is the widest tires that can be used on factory rims ( on my 85) dually?
also any info on rim spacers would be helpful...
Things to consider -
1) if the rear tires touch each other at all, they'll build heat and catastrophically fail.
2) the bigger the spacers, the more stress is placed on them. Spacer failure is not uncommon.
3) steel spacers are preferable to aluminum.
4) spacers add width to the truck. It is not difficult to go over the legal limit of 102", at which point DOT will harass you to death.
My experience with duals on a pickup is not specific to the cucv unfortunately. On my dodge ram I ended up going with 285/75R17 Toyo AT2 tires on stock wheels and 1/2" of steel spacers between the duals. This yields very little space between the rears, but they don't touch, even when hooked to a heavy gooseneck trailer, or with 4000lbs in the bed. I have been running this configuration for about 200,000 miles, and get about 55,000miles out of each set of tires. (285/75r17 ~ 34x11.5)
In your position I'd look at 285/75R16 tires. This is a 33" tire and should look really good on your truck, without requiring much (if any) spacer and without sacrificing anything in terms of load carrying abilities and strength. They'll fit on the stock rims.
JMHO