Mine has 235 75 15's on it, its an 85 I think the stock rims are 7.5 inches wide. I believe I measured it before and the rims and tires total 29 inches tall. did your 89 come stock with 16 inch rims? the tire shop told me i should buy 16 inch wheels when i was looking for some but i found some 15's on kijiji that i liked so i stayed with the 15's

 

My 89 did come with 16 inch wheels, but it is a 3/4 ton. They are just 16x6, so tire size is pretty limited. I'm going to sell/give them away after I order tires since I have two other sets of 16x7 that will work.