Please do NOT run chains in the summer. You will tear the ever-living snot out of the trails, and they will do even worse things to your bodywork, brake lines, and electrical if they are not tight enough or a link breaks. If you run chains on the dry-ish section of trail between mud holes, you will also cause a lot of extra wear on your diff and drivetrain.
With respect to wheeling, chains are appropriate for winter use on icy trails.
A used set of MT's can probably be had in stock-ish XJ sizes for pennies on the dollar compared to new...and they may end up being cheaper than chains anyways.
Any chance that you're driving a white 4 door XJ?