It's been about 8 years but with my grandsons, my daughter said that the recommendation was to use the seatbelts instead of the anchors. I don't recall what the problem was with the anchors.
There's a comparison betweek KO2s and KO3s here: https://www.tacoma4g.com/forum/threads/ko3-versus-ko2-tires-comparison-side-by-side-look-and-technical-analysis.4467/
Just a comment on 3rd-party warrantees.
My brother owns a shop and if a customer wants to use a warrantee, he adds $100 to the bill for the time he has to spend dealing with the additional paperwork and approval process. And if the warrantee doesn't cover the whole bill, the customer must make...