Mazda 2009 Mazda6 Owner's Manual page 429

Customer Information and Reporting Safety Defects
Tire Information (U.S.A.)
70
"70" is the aspect ratio. This two-digit number indicates the tire's ratio of height to width.
D
"D" is the tire construction symbol. D indicates "diagonal ply construction".
16
"16" is the wheel rim diameter in inches.
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
9-29