Nice job, car looks stunning :)
Out of curiousity, is your plate private or were you lucky enough to get a normal reg with LEX as the last three letters?
With regards to the high power washers, I've been using one on my cars for the last 15 years. I've never had any issue with corrosion, even Lexus wheels. I believe Lexus wheels corrode due to the type of alloy Lexus use mixed with the heavy salting of our roads in winter equals corroding flaky alloys. Also it stands to reason for me that you don't hold a high pressure washer next to your tyres. I turn the nozzle to spray not jet when doing the wheels, I stand well back when spraying them and finish them by hand.