Thatonesubiguy

Hey guys, I am currently running stock (17x7.5/5x100/48mm offset) rims and I am thinking about getting new rims. I have stock tires and I dont want to replace them. Does it matter if I get a lower or higher offset on my rims? I am currently looking at the Focal x (flat black w/red stripe) rims they are 17x7.5 with 42mm offset. Link to tires: http://tires.autopartswarehouse.com/wheels/WheelCloseUpServlet?target=runWheelSearch&initialPartNumber=421771842BRS&wheelMake=Focal&wheelModel=X&wheelFinish=Flat+Black+w%2FRed+Stripe&showRear=no&autoMake=Subaru&autoModel=Legacy+Sedan&autoYear=2013&autoModClar=2.5i+Premium&filterFinish=All&filterSize=17&filterBrand=All&filterSpecial=false&filterNew=All&filterWeight=All&sort=Price# What Im wondering is, if I drop the offset 48 to 42 do I need to get new tires, do I need any other equipment to have the tires on, will I need a new rotation/alignment after adding them? I am just starting out and this is my first car that I am modding so any feedback would be appreciated. Thanks!