Im on about 12K now myself & the tyres im using are the bridgestone potenza's. Although wear is fairly good, my results differ....My front tyres have worn about 1-2m, but my rear tyres are half worn! So ive just had them rotated. In my last IS200 I decided to put yokahama tyres on because from previous expereince they have been outstanding on previous cars, no matter what weather conditions, but because they are made of a softer compound they do wear out pretty quick! But they seemed to make little difference to the roadholding on the IS, so a testament to the road holding of the car!!
Ive just stuck with the bridgestone's they seem an all round good tyre!