Jeep Patriot 2013 Owner's Manual page 360

358 STARTING AND OPERATING
compact spare tires have the letter "T" or "S" molded
into the sidewall preceding the size designation.
Example: T145/80D18 103M.
Tire Sizing Chart
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)
• 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.
EXAMPLE: