the flat'ish or roun'ish sidewall does not stand a strong statement anymore judging by the technology involve in tyre making nowadays.

if you have a chance to try between s03 [flat'ish] and re001 [round'ish], you will know there is no much difference between 2 models because of O'bead.

i think re001 on euro is more than enough, but if you drive S15, having a set of S03 will give you more fun than re001...... my 0.2 ringgit