Hi. I just brought home a GS 450h last week. I find the dunlop sp sport 2030 on the rear (sp sport 01 on front and sp sport 2030 on rear) struggle for grip quite a lot.
I've been considering the continental sport contact 5. Theyre about 117 pounds each fitted (from blackcircles), have a C efficiency and A wet grip rating. Noise is rated at 70dB.
Best dunlop alternative in my opinion is the Sportmaxx RT, which is also C, A and has noise rated at 68dB.
Michelins seem expensive in comparison but if you have a costco membership worth calling them and asking what they can do. They often have a 20 or 25% off a set of 4, which makes the michelins very competitive.
I found that the brochures on the lexus site were useful for the spec details, apart from the 2009 cars. There is a brochure for 2008, and one for 2010.
Cheers
Calum