Mazda CX-9 2016 Owner's Manual page 565

Customer Information and Reporting Safety Defects
Tire Information (U.S.A.)
90
"90" is the Load Index. This two-or three-digit number indicates how much weight each tire
can support.
M
"M" is the speed rating. The speed rating denotes the maximum speed for which the use of
the tire is rated.
Letter Rating Speed Rating
M 81 mph
8–29