From what I know, our engine does not require timing chain service (or replacement). However, on some website I read that it is recommended to replace at 90K. What?
Maybe consider the reputation of the website that posted that. Also, keep in mind what type of website it is. If it's a website that sells maintenance parts for you car, such as a timing chain, there could be a little bias there.
As far as what Toyota recommends, mentions nothing about 90k. If anything, periodically check your timing chain (if that's even possible) for damage or need for replacement. Besides, there's many cars with timing belts that require replacement anywhere from 90-120k. You're telling me the timing chain is less durable than a timing belt?