FD - “ It's important that we put any of these rumors to bed, it's just folklore. “.
I just put new 315/30R21 Pirelli Cinturato P7 tires on my stock 21" wheels this past weekend and have no rubbing issues nor any problems with the setup whatsoever. I love these tires and the width just gives it a much more aggressive stance and much better traction. I have not put on any spacers and I most likely will not so I apologize if this doesn't help. BTW.. I have two more "BRAND NEW" Pirelli Cinturato P7 tires in the same size if you are interested.
Have a good day,