Width is 6.5" and offset is 114mm (4.5"). Width is stamped on the wheel (16x6.5JJ) and offset can be measured by putting a piece of straight wood or metal on the inner lip and the distance from it and the wheel hub is your offset.
Here is a list of possible wheel/tire size combination:
Width Ratio Wheel Circ. %
215 65 16 27" 100%
215 60 17 27.16" 100.57%
230 55 17 26.96" 99.84%
225 50 18 26.86" 99.46%
230 50 18 27.06" 100.19%
Above combinations would not mess up the speedometer, but if you plan to lower the car, don't change the wheels until you do because you want to make sure the new wheels/tires would clear the fenderwells and gas filler tube unless you stick with 215 width.