For information, I have just renewed my 2005 Sirion's discs as they were warped - or so the garage and I thought. The actual cause seems to have been flecks of rust between the disc and hub - lodged there when the tyres were changed I guess. Poor design I think as there is a reasonable gap between the hub circumference and the disc's bore - most car's have a narrow gap, a mild interference or better still, a screw to hold the disc in place. So the message is: take car after you change tyres as the disc is a very loose fit. If I'd realised sooner I could have reset it before the pads wore the disc unevenly. I hope this post helps someone.