Hopkingsmemsns I can see what you mean... I rememer joining the bandwagon in fitting 175'50's to a set of 13's, The difference between a set of Toyo Proxes and Dunlop SP9000's was probably about 3/4's of an inch in width!! Couldn't believe they were the same tyre!!
As for 195/40 on an 8J rim, thats gonna be a LOT of stretch, I've got 195 45 on the front of mine and that has about a 25 to 30 degree angle tyre wall. I'll be replacing them (very soon from the last check) with a set of 195 40 to match the rear 205 40 better (tyre wall at front is bigger - i know its all to do with ratios and percentages and all that crap, it still looks noticeably bigger)
Anyways, from seeing 195'40s stretch on a Corrado with the same wheels as me I decided it needed to be done on mine!!