No you are right Pete, you just need to make sure you don't go too mad as you don't want the tire coming off. This is 165/50/15 stretched onto a 7 inch rim, not as wide overall as the 195 comes out at around 185 the contact patch is 2 x good.
We find 195/50 888's are just too bouncy, the side wall are bloody huge like a tractor! It all depends on wheel width as well. If your munching side walls that quickly look into your suspension/chassis setup as well, looks like it's running quite high. What bound and spring rates are you all using and what about bushes?
I only have last years prices from Hoosier but see as follows:
For circuit ;
P225/45ZR-15 DOT Sports Car Radial slick @ £154.00 + vat each
P205/50R- 15 DOT Sports Car Radial WET @ £150.00 + vat each
I don't have any other sizes or prices at the moment as these were for our 9inch wide rims but can get them. The main problem with such small wheels like 15's is choice, not many out there. I tried and tested so many sizes and got the best results from the stretched tires as 195/50 just wasn't right at all, comparing contact patches and overall tread. The yok a048r is another competent road legal semi slick.
It's not that stretched tires have more contact it's just they don't do the right sizes for our little cars so we had to stretch to get the best results.
T