As the other said, what do you want? There is no right or wrong answer*. 10" are best 12" is good and 13" is considered by most to ruin the classic handling.
Also consider the rim width. Too wide a wheel (6-7"+) and the steering becomes heavy. 4.5-5" is best and 5.5" is ok. 6 &7+ serves no appreciable advantage for a road car.
IMO if you can't fit 10"over your brakes or you just want larger then 12x5 with a 165/55 is the smart option. You can fit a 165/ on a 5.5" rim (and many do 'because they like the look) but really its to narrow a tyre and ends up looking like this:
