Measure the width of your bed on the underside where if fits down over the frame. Add 2" to that measurement and then bolt your wheels/tires onto the rear end. If is less than this figure between the insides of the tires it's too narrow. Now measure from outside to outside on the tires and then from outside fender bead to outside fender bead. If the tire width measurement is wider than the fender to fender figure it's too wide. Check into spacers and wheel back spacing to see if you can position the tire for inside/outside clearance. On 10 inch tires one usually has to jack up by the bumper or frame to remove tire.

Evan