92 Ill. Adm. Code 442.255
Mirrors
Section 442
Section 442.255 Mirrors
a) Interior Mirror – A mirror shall be located inside the bus.
It shall be firmly supported, constructed of clear view safety glass and
securely backed and framed. It shall have rounded corners. Edges shall be
padded to reduce danger of injury upon impact. The mirror shall afford the
operator a good view of the bus interior and portions of the roadway to the
rear.
b) All exterior mirror systems shall conform to the applicable
requirements of the FMVSS 111 (49 CFR 571.111).
c) More convex mirrors than required above may be installed, if
specified by the purchaser.
d) The reflecting surface on the backside of each mirror glass
shall be protected from abrasion, scratching, and atmospheric corrosion.