Knoxrower

Time for new tires for the C6 coupe. I'd like to upsize as I autocross but also daily drive as well. I'd like to stay in AS so they'll need to fit on the stock wheels. I'm concerned about not change the ride/handling in a negative way for daily driving. I've seen upsize recommendations of 255/40/18 and 295/35/19. But looks like most people go straight to 305's..
Any recommendations or threads out there on this?