stock offset, you DONT need fender roll.
even if you go super low.
anything different than aftermarket offset, you may need a roll.
I 100% suggest you DONT try to do it yourself. It is very easy to really mess up, and when you mess up outside fender paint it is OBVIOUS and an expensive fix.
get someone who knows how or pay.
Fender Roller is the tool they sell, but rubber mallets some people are pro with, is the way i got it too and it looks smooth and professional.
i'm lowered on hr's, stock wheels and no rubbing at all. but if you go wider like18x8, then you'll prolly need a roll.