Dear Aspirant,

Your question is not 100% correct. The reserved seats in Govt. colleges as you have pointed out 85% are reserved, most of the time for the state students. These seats do not have any share of management quota in them. However, they may have OBC, SC/ST reservation in this 85%. The rest 15% is for ALL INDIA quota. 
The management quota which you are talking about is actually in the private colleges. And in private colleges, there is no such quota like 85% for the state students. Both of these things are separate. Hope this clears your doubt.

Thank You.