Has anyone tried using 245-45-18 tires on all 4 wheels on a 2003 coupe?If possible tires could be rotated.

 

I believe there are a few who have done it, but since the VDC system counts on a tire diameter difference between front and rear, you'll run the risk of VDC not working properly (i.e. kicking in at the wrong time) or not working at all.

 

Also the smaller rears will tend to increase the oversteer potential for the car (less traction in rear + same traction in front = more oversteer).