1. Remove the hub caps from the rear wheel.

2. Remove the rear axle nuts from the rear wheel.

3. Turn the chair on its front side.

 

4. Remove one of the rear wheel by removing the rear axle.

5. Install the axles into one of the new rear wheels and through one of the axle spacers, if used.  Install the into the frame of the chair and tighten.

6. Install an axle nut on the new axle and tighten.  The axle has to be held in place while tightening the axle nut to prevent the axle from backing out.