What goes to prius there are good points shown, but I say few more:
- Prius aerodynamics and add on parts is designed to work best on that car which gives that 0.25 cd. So if you put wider tires air dont go smoothly pass the tires as they are optimised. That about one inch more wider tires dont seem much but if look that at you 3D computer screen you immediately see that who has designed something this much wrong when designing tire spats etc.
- Larger wheels and tires weight more, that has huge effect on city driving and in P&G "mode"
- rims might have less aero look. Prius original rims are optimised for aero vs looks to prius. Aftermarket rims only for looks.
- low profile tires are not best for rolling resistance
New Michelin Tires Designed For EV's and Hybrids
Michelin thinks 175/70 R10 would be best bang for buck when it comes to fuel economy tire. So 175 tire can have enough load ratings vs low rolling resistance characterics. Sad that they are not yet availebly :/.