it depends on what you want the car to do, or look like it can do, anyways.
if you are building a drag racer- or something that looks like a drag racer- then go really wide in the back with wider tires, and as skinny as you can in the front. 15X9 in the rear with big, meaty tires with tall sidewalls like a 275/60/15 and 15X4 in the front with a tall, skinny tire in the 205/75/15 range for less weight and rolling resistance, for example..
but if you want it to take corners- or look like it can take corners- then go wide all around with lower profile tires.
the same 15X9 rim as the drag combo with a 275/50/15 tire in the back, but with a 15X8 in the front with something like a 245/50/15 would fit the bill nicely and look extremely badass with the proper wheel style slection.