There are a few hints during the interview that this might not be from 1989:

-That the tour was announced in NYC with the Stones playing on a flatbed truck driving down 5th Avenue.
-That it was the first tour for the new Stone, Ron Wood.
-That the album being promoted was the compilation "Made in the Shade."
-That a large part of the new and stupendous stage was designed by Charlie Watts.

But of course the real giveaways are the two times the interviewer says that this is the Stones 1975 American tour!

Anyway, the interview seems to have been done in Boston on June 6, 1975. It is mentioned that Cleveland is the next venue and that there are just six days until the Madison Square Garden shows.

Other than listening to Mick describe how Bill Wyman fell off the new stage I thought the best part, and the part where Mick seems most engaged, is towards the end when he shows off his London School of Economics background and discusses taxes and capitalism.

I have, so far, only listened to a few interviews but it's great stuff. Where else can you find a two hour interview with Mick? But I must say, given the great attention put forth by CV to nail down set lists, concert dates/venues, and band personnel, I'm disappointed at the short shrift given to the interviews. It's like there's a big box of tapes in the basement labeled "Interviews" and that's it. Don't know where it was done, don't know who the interviewer was, don't know why the interview was taking place. You've got gold, guys, mine it!