And what if it's Penn St., Ohio St. and Michigan?
If you go merely geographically it would be Maryland, Penn St and Ohio St.
Sure love to be Purdue. Indiana, Northwestern and Michigan St.
Be careful what you wish for.
If there are 3 "permament" (nothing is permament) rivals for each school you'd have to figure it all out at once. Probably starting with the traditional trophy rivalries.. not sure what all of those are.
Wiki suggests this (latest year suggests game is not played every year now.. or CoVId was responsible):
I think this would be the starting point for determining 3 rivals for each team.. you can see there are issues already... I'll leave it to others to "do the math" on this one..
Illinois - NW, OSU, Purdue
Indiana - Purdue, MSU
Iowa - Nebraska, Minnesota, Wisconsin
Maryland - *Penn State (no trophy)
Michigan State - Penn State, Indiana, Michigan, Minnesota (oops.. that's four!)
Michigan - Michigan State, Minnesota, Northwestern, *Ohio State (no trophy) (oops.. that's four!)
Minnesota - Nebraska, Penn State, Wisconsin
Nebraska - Wisconsin, Iowa
Ohio State - *Purdue (no trophy), Illinois, Michigan (no trophy)
Northwestern - Michigan, Illinois
Penn State - Maryland, Michigan State, Minnesota
Purdue - *OSU (no trophy), Indiana, Illinois
Rutgers -
Wisconsin - Iowa, Minnesota, Nebraska