go to autozone get some black wheel paint, take off your wheels if you dont want overspray on your jeep. Clean wheels with simple green etc to get road debri oil off, scuff up with some 3m/scotch brite pads, wipe down with xylene, tape off the tires with some news paper. Then paint the wheel. Done.
Or get a little artist craft paint brush some black paint and skillfully trace over the line with black paint for the easy route, still would want to degrease and wash the rim so it adheres though.