I have 305 on my rears and they fit fine with a 20x10 rim. I recently went with a bigger rear rim 20x10.5 and you will need spacers, they will not fit without them.
I had Continental Extreme Contact on my 2009 SRT 8 when purchase. The were so hard they left a pile of dust instead of melted rubber. I have 275/40-20 Nitto NT 555g2's now. The Nitto's hook good when cold and great when hot. The Nitto 555G2 has a 305 that will fit on the stock rims as the run narrow. Good luck finding some! They were out of stock everywhere the shop called. If anybody in west central IL has a new set of 305 G2s to sell give me shout.I have a 2010 Challenger SRT8, 6 speed Manual, Kenny Belle liquid cooled supercharger, Corsa exhaust, Hurst short throw shifter and American Racing Black Rogue 20x8.5 wheels with 255/45ZR20 Continental Extreme Contact tires. I want to run wider tires and my wheels are discontinued...so starting over with new wheels & tires.
I am sure this is an exhausted subject so I apologize in advance...but I want WIDER tires! I am looking at Centerline 635B Satin Black wheels 20x9 with +18 offset up front & 20x10.5 with +25 offset for rear. Tires will stay Continental Extreme Contact 275/40ZR20 up front & 315/35ZR20 for rear. Anyone currently running these tires or wheels and if so, any issues?