Ram Trucks 2013 Chassis Cab - Owner Manual - Manual (Page 308)

compact spare tires have the letter “T” or “S” molded
into the sidewall preceding the size designation.
Example: T145/80D18 103M.
• High flotation tire sizing is based on U.S. design
standards and it begins with the tire diameter molded
into the sidewall. Example: 31x10.5 R15 LT.
Tire Sizing Chart
EXAMPLE:
Size Designation:
P = Passenger car tire size based on U.S. design standards
؆....blank....؆ = Passenger car tire based on European design standards
LT
= Light truck tire based on U.S. design standards
T or S = Temporary spare tire
31 = Overall diameter in inches (in)
215 = Section width in millimeters (mm)
65 = Aspect ratio in percent (%)
— Ratio of section height to section width of tire
10.5 = Section width in inches (in)
R = Construction code
—
ЉRЉ means radial construction
— ЉDЉ means diagonal or bias construction
15 = Rim diameter in inches (in)
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