Just a week back, I upgraded by Petra to new Alloys and wider profile tyres from stock rims and s322.
Alloys : 98 pcd OZ racing 15 inches width- 6.5J.
Tyres : Yokohoma S Drive - 205/50/R15.
One thing for sure is that ride quality has not detoriated even with lower profiles (205/50), that means S drive are meant for comfort. another visible difference I can judge is that tyres noise have reduced by atleast 30-40%.
No differnce in Handling /Steering etc and car have giving same milage(10.5 kmpl in city) as it used to give with 175/65/R14.
Will write my driving experience about other aspects like performance/ Braking etc once I go for a long weekend drive.
Some pictures of the Car with this upgrade have been uploaded in my Pic gallery.
OZ racing Alloys 
Yokohoma S drive 205/50/R15 Tyres 
Car Back Side view 
Just waiting to go on a long Drive.
Cheers
GD