Chevrolet 2014 Silverado 2500HD Owner's Manual page 466

10-100 Vehicle Care
Use the following guidelines for
proper floor mat usage.
The original equipment floor
mats were designed for the
vehicle. If the floor mats need
replacing, it is recommended
that GM certified floor mats be
purchased. Non-GM floor mats
may not fit properly and may
interfere with the pedals. Always
check that the floor mats do not
interfere with the pedals.
Use the floor mat with the
correct side up. Do not turn
it over.
Do not place anything on top of
the driver side floor mat.
Use only a single floor mat on
the driver side.
Do not place one floor mat on
top of another.