Setting the record straight. You CANNOT fit 275 55r20 on 9” wide rim with 20mm offset on rear on 2013 Dodge Challenger R/T. Not even close. The wheel well is not big enough. You can, however very closely fit 255 45r20 in front and rear. Front is pretty close, but does fit. I’m going through hell here at Goodyear trying to fit the tire I want, and it’s just not happening. I came to put 255 50r20 in front, and 275 55r20 in the rear. That’s a big NO GO. That being said, it can be due to offset for the front, and the rear is just not big enough to fit a 20x9 20mm offset rim with 275 55r20. This is possible that this is just for 2013 models. So what I’m settling with is 245 45r20 in front, and 255 45r20 in the rear. I hope this information helps. Always research offset!