its the width of the tyre that mostly determines whether u will have massive stretch or not.
for instance for a 7 inch wheel, 205 tyres would sit flush with the edge of the wheels, 215 tyres is a tad wider, but still reasonable, 225 tyres is a bit pushing it, but i think mostly used on track/drag cars
for 8 inch wheel, i would say the "safe and legal" size would be either 215 or 225, from there its up to you to choose the profiles that would suit your car best, taking into account rubbing issues etc etc.
i found this from honda tech, just for your reference
i had 195/50/r15 on mine, this is raw fitment without camber kit
http://img9.imageshack.us/img9/2375/img0811pd.jpg
this is after camber kit (-3deg camber)
http://img824.imageshack.us/img824/3443/img1480ui.jpg

