When you change your wheel and tires on your Jeep, depending the size you may need wheel spacers. These 1.375 inch wheel spacers/adapters move your wheels out to help fit wider tires while at the same time converting your 5x5 bolt pattern to 5 x 5.5 bolt pattern. This will allow you to use Jeep CJ wheels on your JK.
Each kit comes with (2) aluminum spacers, (5) grade 8 wheel studs pre-pressed in each spacer, and (10) lug nuts. This kit bolts on in the same manner as installing a road wheel.