Not certain, but it sounds like a design issue of your vehicle? I've driven all sorts of vehicles, and my RX400h has worn out tires faster than any others I've owned in the past.
Premature tire wear. The service manager thought I did well by going 30k on these Goodyear Eagles, where he's seen some with only 12 or 13k miles on this brand of tires before it needs replacing.
Any suggestions or comments? has Toyota/Lexus done any rebates or recalls concerning this?