It won't do much good for anyone here, or anywhere else for that matter, to toss you a number. At best it might be an informed guess if they've had a similar car and have played the game. You've got the actual car, you should measure from what you've got to what it will accept. Not all cars were built the same, so tolerances will vary. Also, if your car has had any body work done in those areas it may have more or less than what it started with. Besides tire size, you also need to consider rim width, and offset.

Here's a calculator to help get you started on the tire size;
http://www.mindspring.com/~cinque/test/tirecalc.html