Can i strech tires on a 17x6.5 ? HELP

[i12drivemyMP5]

Wheel related question/ controversy:

I tried comparing stock 195/50/16 wheels w 205/45/17's to figure out what my speed reads now. And both sites have different final answers! : Which is correct?! :

The miata tire size calculator says 61.5 doing your comparison so I'd say the discount tire one on the right is correct. The 205/60/17 is the bigger of the 2 sizes so the speedo will be slow, smaller OD and the speedo will read fast. Link to calculator...........
http://www.miata.net/garage/tirecalcold.html

 

[Taus-MP5]

Its comparong 205 "45" 17 not 205 60 17

And thanks for the link!