Father:
20k miles used on 70k mile warranty. 6/32 remaining of 11/32 factory. 28.5% of miles projected. and used 6 of 9/32 available, or 2/3 of available life used. Suggests you had 10k miles left, or 30K total life.
1) Yep, pretty good for America to warranty them at that point!
2) Tires are roughly $1.200, 30/70 is 42%, so 58% of that is what you didn't get, or $696. So maybe not such a great amount of credit.
Certainly interested in what you experience w/the Conti's. I too fear a range fall-off, but that's going to take some time to settle out so....
Luck to you, and thanks for the reports!