Mich. Comp. Laws § 224.7
Any person elected or appointed county road commissioner shall, within 10 days after being notified in writing by the clerk of such county of his election or appointment, take and subscribe the constitutional oath of office and file the same with said clerk. Each and every county road commissioner shall be required to execute and give official bond in such amount as the board of supervisors of such county may determine, the expense of securing such bond, if any, to be paid from the county road fund. The term of office of the first commissioners elected or appointed in any county under this act, shall commence immediately upon filing such oath of office and bond, and shall continue as herein provided. The successor to each such commissioner shall be elected at the general election on the first Tuesday after the first Monday in November preceding the expiration of his term. They shall hold office for 2, 4 and 6 years respectively, from the said first day of January; and thereafter 1 commissioner shall be elected or appointed biennially for the full term of 6 years. No member of the board of supervisors shall be eligible to the office of county road commissioner, and such offices shall not be held by the same person at the same time.
MCL 224.7