SRB Power ltd

I think you're best bet's going to be the main dealer, as it's so new. I've had a little look through my book and all I can input for you is that the entire range of Lexus models have the same 114.3 pcd and 60.10 centre bore. Offset varies but appears to be 40. Obviously not sure if the RX300 will be the same, but it's a start:)