I basically went through the same thing.. wear and tear, so after politely informing him that I would tear off his head and make him wear it he offered to replace all the tires for free, as long as I purchased the spare and the kit to put it in the trunk (about 700 cnd) this I did, and the ride was worth it.
Personally in this day and age I have never found a manufacturer to offer such wonderful service as Lexus, their quality and build is second to none.
ps I don't work for them.