Hello, i know that many people say that it would take a lot of work to get 15" wheels on a viva, And today i test to mount a wheel from a Saav 9000 i know that the measurements are wrong but just to see what it looked like and if it hade enough clearance... I dont think it looked to be so much work to make it fit... Some pictures:
All I think you would have to do is: cut away alittle bit on the piece in the front, and make the corner good, In the back i think it would be enough to just use a hammer Although if u whould have a low profile tyre you might not would need this
I think i will use lowprofile 15" wheels or maybe 14" wheels...
//Alex