I think a 10" slick on an 8 1/2" wheel with a 5" back spacing is going to put the outer edge of the slick outside the fender lip. The 1st gen Dakota came with a 15 x 6" and either a 3 1/2" or 4" back spacing, and those tires were close to the wheel lip.
I'm posting a picture of my 93 4x4 with the standard 15 x 6" wheels and a 235 75 x 15 tire. you can see how close the wheel tire fit to the box wheel lip. Gene