Will I have fitment problems with this rear combo. Im looking to run a 285/35 and eventually a 315. Will I have fitment problems with the Sportline drop or should I stick with 17" or maybe 9.5 width wheels. Any help appreciated.

 

Difficult answer that question without knowing either the offset or the backspace on the 18x10.5" wheel. You would probably have the least chance of rubbing with a 50-52mm offset (~7.75" backspace).