[ayao]

Just as an added data point, a little while back I testfit a stock M3 18" rear (265/40/18) on the front and it rubbed loudly starting at ~ 50% lock. It wasn't subtle. This was on revised liners and -2.5 camber.

That tire size is just about equivalent in diameter to a 265/35/19, so I'd be cautious putting stock 1M rears up front, if you think rub will bother you.

A 265/30/19 is about 0.5" shorter than a stock 245/35/19 and about 1" shorter than a 265/35/19 ... so I think you'd be ok on rub -- however the caveat is that I don't know if the decreased tire diameter on a 265/30 will negatively impact driving dynamics, DSC, etc in other unforeseen ways.

Are you looking for a tire that fulfills both street and track duty? Something else to consider would be hitting up Apex for some advice on their 19" EC-7s which look pretty close to stock. They're doing a free shipping deal through the end of the month.