Actually, the 255/35/19's will better match the current rears (305/30/19) that you have right now, and are in spec with OEM diameters...see below.
OEM sport:
245/40/19 = 26.7"
275/35/19 = 26.6"
Your current:
255/40/19 = 27.1
305/30/19 = 26.3
Possible purchase:
255/35/19 = 26"
Compared to your current front set up, you'll have 0.5" more wheel well gap and the front will sit roughly 0.5" lower because of the difference in diameter...but front and rear diameters are better matched.
