GarageCalc What 155/60R15 means
155 is the section width in millimeters (6.1 in). 60 is the aspect ratio: the sidewall is 60 percent of the width, so 155 × 0.60 = 93 mm (3.7 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 × 93 = 567 mm, or 22.3 in.
A full marking adds a load index and speed rating after the size, for example 155/60R15 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 155/60R15
No common 16-inch size stays within 3 percent of 22.3 in. Going down one size, 175/60R14 is -0.2% with a taller 105 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 155/60R15 tire?
22.3 inches (567 mm) in overall diameter: the 15-inch wheel (381 mm) plus two 93 mm sidewalls. Real tires land within about 1 to 2 percent of that depending on brand, tread depth and pressure.
What is 155/60R15 in inches?
22.3 x 6.1 R15: 22.3 inches tall, 6.1 inches wide, on a 15-inch wheel. The sidewall is 3.7 inches and the circumference is 70.1 inches, so the tire turns 903 times per mile.
What tire sizes are equivalent to 155/60R15?
Within 3 percent of the same diameter on the same 15-inch wheel: 175/55R15 (+1.1%), 175/50R15 (-1.9%), 165/60R15 (+2.1%); on a 14-inch wheel: 175/60R14 (-0.2%), 165/65R14 (+0.5%). The percentage is the diameter change, which is also your speedometer error.
Can I use 165/60R15 instead of 155/60R15?
Dimensionally yes: 165/60R15 is 2.1% taller (+12 mm) and 10 mm wider, and at a true 60 mph the speedometer would read 58.8 mph. The extra width needs about 0.20 in of clearance on each side of the tire and a rim width that suits 165 mm.