I think overall, this poll or desire to make tire costs more economical is fantastic. However, I fully believe the thought process of considering a 195 tire for SM, is 100% in the wrong direction and would make tire budgets increase. I discussed this with our tire simulation engineer earlier today from work too, so hear me out for a second...
A skinnier tire doesn't necessarily mean a loss in grip, in fact I would expect a stretched 195 to be slightly quicker than a 205 (on the same 7" rim) due to the sidewall stiffness change.... until the tire overheats!
As it sits today with our 205's, tire management plays a key role near the end of any race. We hear this time after time with the post race interviews. With a 195, of the same sm7 compound, tire management would play a bigger role than it does today.
Therefore, I would actually suggest moving towards a larger 225 tire on the same rim.
But wait, what about all of our cracked subframes!
Harden up the compound ever so slightly to reduce the overall grip of the tire. Hopefully, with the harder compound and increased thermal mass of the system, this combination would yield more usable heat cycles from the tire.
But none of that can be proven on the internet from behind a keyboard. Lost of testing,$$$, and confusion. In the end a larger, harder tire might work, but then again it might be faster when shaved. So maybe this issue we have today, isn't all that bad.
I will however, smash my keyboard if a smaller tire remotely seems like a good idea
Like Jim said the perfect tire is not as easy as some would think. SM tried and failed with the 888. FE is failing with the AR tire. The SM6 would grain real bad at some track. The RR requires saving at some tracks. The RA1 was only fast when it was worn out.
The amount of testing to insure a tire is a success would be costly and very time consuming. If it was easy everyone would be doing it.