actually i kinda agree. i always feel the rabid push to upsize the tyres is almost like a disease and many people end up using their 17" till its botak before changing.

our roads are not perfectly flat and running higher profile tyres that can deform to cater to the imperfection on the road surface actually makes more sense than running a super stiff tyre.

another thing is that pressure = force/area. so at a given pressure the contact patch on the road is the same regardless of how wide the the tyres are (ofcoz the compression and subsequent heating up of a narrower tyres is another issue altogether).

thicker sidewalls also means that bad roads are less painful to drive over slightly quicker.

last but not least, at 15" i can afford to change my tyres whenever they are at 50% and get new tyres and still be cheaper than those running 17" or even 16" until end of life.

yup... and the other thing is bigger rims dun necessary mean nicer looking.

i've seen many damn big rims but no upgrade of brakes and hence end up with a big space between brake disc and rim, which optically make the disc appear even smaller than it is. imho. that is ugly.

i rather have smaller rims and this would make the disc looks bigger.

ofcoz taste is subjective, just stating my preference.

out of proportion and slower to accelerate.

Well... as far as distance covered per revolution then yes. you cover more distance per turn of the wheel.

However, that is if you use oversize tires which you are not supposed to. when u increase the rim size you decrease your profile size to maintain the same overall wheel size.

but even if one decides to just screw the speedo calibration and just opt for bigger wheels, there are still too many factors to consider.

the most obvious is that air resistance means that the engine has to keep pushing to keep the wheel rolling and a heavier wheel is harder to spin regardless if the car is accelerating or cruising along as you have to constantly work against all the resistive forces. not forgetting bigger tyres require more torque to turn simply coz the radius is bigger.

one area where wider tyres might save energy is that it does not have to deform as much as thinner ones to maintain the same contact patch to the ground and hence less energy wasted in rubber hysteresis.

then there is also the question of air drag on wider tyres.

in conclusion, there are too many factors to consider whether a bigger diameter wheel will be more fuel efficient than a smaller one. and whatever i state above are extrapolated from conventional wisdom, and we all know how reliable is conventional wisdom so please improve upon/correct me if i got the concepts wrong.