I highly doubt that 15" wheels would fit on your car cause I don't think there would be enough clearance for your brake calipers. But even if it did, 195/60/15 would affect your speedometer a bit since you are going to a smaller wheel and a smaller tire sidewall, you'll doubly affect your speedo accuracy.
Remember the "60" in 225/60/16 represents how tall the sidewall in percentage terms. As in, 225/60/16 means that your sidewall will be 60% of 225 mm which is equal to 135 mm tall. 195/60/15 means that you sidewall will only be 60% of 195 which equals only 117 mm tall. Add to that the fact that your wheel diameter is smaller than an inch, you are then going to be a total of 1 inch and 36 mm smaller in overall diameter, thus affecting the rotational speed in relationship to linear speed.