First off, I do find it strange how very few tracks have actually said much on the rule in the first place. Some really not at all.
Most tracks tend to post here as well, and again haven't seen any of them make mention of the tire rule.

Anyways let's get down to it.

Kokomo and Gas City are now Confirmed to be using this rule. There is a news article about it on Kokomo's track website. Posted March 28th.

MSCS and TriState is also using the rule, as expected since Hoosier has a lot of sponsorship with the series. Which of course is based in Haubstadt.

Lawrenceburg has amended their rules on March 28th to revert back to the RR only.

Bloomington has only made a Facebook post about the rule. No other mention has been made. The rules on the track site are for 2015 and have not been updated. But the post did state they were going to use the rule.

Lincoln Park...I haven't seen a yay or nay honestly. The only mention of a tire rule on the track's site is the RR spec rule from 2014. There might of been something I missed, but either way it's not clear. Rumor is they too are gonna use the rule.

Paragon doesn't have their Sprint rules posted, but they likely will remain very open as they've always been.

BOSS series is not running the tire rule as pointed out by the promotor in the previous thread.

USAC is sticking with the RR Spec tire only.

That about sums up most of the tracks and series who run weekly or frequently enough to be mentioned. Most other tracks either run only a special show or two or have one of the previously mentioned series attending. (Terre Haute for example)

All in all that is about the gist of what can be gathered so far. So it seems like just about every major track is on board in using the all 4 Hoosier rule.