Judging by the pictures...yes, I know that's not accurate...but the new GT350 is sporting some rather large meats up front. 275-285 for sure.
Considering I ran 275's up front on my 2013 (very safe fitment) and many others have run much wider than that (autoX and track guys)...I don't seen an issue with getting wide tires up front on the new S550 platform.
2013 Mustang GT - 402A GT/CS - 6R80 - Glass Roof - Engine Block Heater - SGM Exterior - CB/Miko Interior
Steeda Adjustable PHB (Street) and Steeda PH Brace, Stainless Works Retro Catback Exhaust...