GarageCalc What 185/60R15 means
185 is the section width in millimeters (7.3 in). 60 is the aspect ratio: the sidewall is 60 percent of the width, so 185 × 0.60 = 111 mm (4.4 in). R is radial construction, and 15 is the wheel diameter in inches (381 mm). Stack two sidewalls on the wheel and you get the overall diameter: 381 + 2 × 111 = 603 mm, or 23.7 in.
A full marking adds a load index and speed rating after the size, for example 185/60R15 91V. Those two codes set how much weight and speed the tire is certified for; look them up in the load index chart and the speed rating chart.
Plus and minus sizing from 185/60R15
Going up one wheel size, the closest match is 195/50R16 at -0.3% diameter with a 98 mm sidewall instead of 111 mm. Going down one size, 175/70R14 is -0.4% with a taller 123 mm sidewall for more comfort and pothole margin. Anything inside 3 percent keeps the speedometer, ABS and gearing effectively stock; the comparison calculator shows the full speedometer table for any pair.
Frequently asked questions
How tall is a 185/60R15 tire?
23.7 inches (603 mm) in overall diameter: the 15-inch wheel (381 mm) plus two 111 mm sidewalls. Real tires land within about 1 to 2 percent of that depending on brand, tread depth and pressure.
What is 185/60R15 in inches?
23.7 x 7.3 R15: 23.7 inches tall, 7.3 inches wide, on a 15-inch wheel. The sidewall is 4.4 inches and the circumference is 74.6 inches, so the tire turns 850 times per mile.
What tire sizes are equivalent to 185/60R15?
Within 3 percent of the same diameter on the same 15-inch wheel: 205/55R15 (+0.6%), 175/65R15 (+0.9%), 165/65R15 (-1.2%); on a 16-inch wheel: 195/50R16 (-0.3%), 185/55R16 (+1.1%); on a 14-inch wheel: 175/70R14 (-0.4%), 195/65R14 (+1.0%). The percentage is the diameter change, which is also your speedometer error.
Can I use 195/55R15 instead of 185/60R15?
Dimensionally yes: 195/55R15 is 1.2% shorter (-8 mm) and 10 mm wider, and at a true 60 mph the speedometer would read 60.8 mph. The extra width needs about 0.20 in of clearance on each side of the tire and a rim width that suits 195 mm.