175/50r13's - will be very small compared to stock however - your car really needs to be very low to pull it off.
Have a look at Gal's 1200 sedan, or Nicole's ute to get a idea of the tyre.
If you want a bit more wall you can up it to 175/60r13 quite happily, or for even closer to stock 185/60r13. There's some weird 165/60's, but to be honest you're better off with the aforementioned sizes.
If you get stuck let me know and I can freight to you.