Assumiong you have a 2009 Jeep JK, you have a gap between the plastic bumper and the plastic fenders, like this;
You could bring it to a plastic welder to have something rigged up (Seen a guy neer me that does plastic weld out of his garage), or you could buy the AEV bumper that fills in the gap, like this;
Or buy boring street tires that don't throw rocks, but that's pretty lame
Or, Get a suspension lift.