Yesterday evening, I had the opportunity of driving a white 5 door Mk6 GTI with ACC and 17" wheels shod with Bridgestone Potenza tyres. Needless to say, I compared it with mine which is very similar but has 18" wheels and Bridgestone Potenza tyres.
Both cars had full tanks of petrol and the tyre pressures checked when cold. I also had a Bruel & Kjaer sound level meter to hand. Both cars have done approximately 3500 miles and tyre wear was exactly the same. We drove the cars in 'Normal' and 'Comfort' modes.
This is what we found:
(1) The 17" wheels poduced less noise by approximately 1.7 dB(A) averaged over a couple of measurements. They really felt quiter. We did not conduct dB SPL measurements or a 1/3 octave band frequency analysis.
(2) The 17" wheels produced a more compliant ride in both 'Comfort' and 'Normal' modes. There was much less crashing over sharp ridges.
(3) We also found the ride in 'Normal' mode with the 17" much more acceptble.
(4) In 'Comfort' mode, the 17" produced a magic carpet ride.
(5) The 18" wheels prduced very slightly better handling for me (very subjective), though my friend preferred the ability of the 17" in this respect.
(6) The 18" wheels looked infinitely better.
I hope you don't mind me starting a thread on this topic.
As for me, I am glad I got the 18" wheels, as I am a show-off and the Blingmiester.
