OK, I'll give you my two cents worth. You are limiting yourself when you say you dont want to go any wider on the back than the front - I assume by this that you want the same tire and rim combo all round. You dont say what size wheels you want, 14 or 15 inch, but I will assume you are looking at 15 inch rims.
Given the above I would say you could go no larger than 15 x 7 inch rims with 225/60 tires. Even then the 225/60 tires may well provide you with some rubbing/interference up front with the wheel at half to full lock and going over a bump (eg. entering a driveway). 215/60 tires would be a better size for the front, in my view.
225/60 tires would fit comfortably in the rear - depending on your axle and rim backspacing of course. 235/60 would also fit on the rear. 245/60 and larger and you may well start to have clearance problems.
To recap the above, if you want to stick with same rim/tire size all round my best advice would be to go with 15 x 7 rims and 215/60 tires.
Otherwise, if you're not totally wedded to the idea of same size all round I would suggest going 225/60 or 235/60 rear and 215/60 front, for an ideal combo that should not present any real headaches.
Hope this helps.
