basiclly mate not any wheel will fit on any car, the offset (bolt holes) have to be the same so it will go on your car. so you cant pull a set of renault alloys and fit them str8 to ur saxo, get it?
You should have a spare?
Also, the bigger inch your alloys the higher the ride hight of your car, you'll only have problems with arch lining etc when you start pushing 17"+
the thing to do to adjust the ride hight is get the car lowered and thats a whole new ball game!
hope this helps