X's are not higher than Sports. 285's are as big as you can go without lifting. Even then you need new wheels or spacers to accommodate the width of the tires. If you lift it 2.5" you can fit 35's on new wheels. There is a ton of info here about lift/tire sizes for JK's... Even if it isn't always easy to find
Spacers are less expensive than springs, and while springs are preferred, spacers are quite functional as a means of lifting the Jeep.