GarageCalc What 155/80R13 means
155 is the section width in millimeters (6.1 in). 80 is the aspect ratio: the sidewall is 80 percent of the width, so 155 × 0.80 = 124 mm (4.9 in). R is radial construction, and 13 is the wheel diameter in inches (330 mm). Stack two sidewalls on the wheel and you get the overall diameter: 330 + 2 × 124 = 578 mm, or 22.8 in.
A full marking adds a load index and speed rating after the size, for example 155/80R13 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 155/80R13
Going up one wheel size, the closest match is 175/65R14 at +0.8% diameter with a 114 mm sidewall instead of 124 mm. No common 12-inch size stays within 3 percent either. 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 155/80R13 tire?
22.8 inches (578 mm) in overall diameter: the 13-inch wheel (330 mm) plus two 124 mm sidewalls. Real tires land within about 1 to 2 percent of that depending on brand, tread depth and pressure.
What is 155/80R13 in inches?
22.8 x 6.1 R13: 22.8 inches tall, 6.1 inches wide, on a 13-inch wheel. The sidewall is 4.9 inches and the circumference is 71.5 inches, so the tire turns 886 times per mile.
What tire sizes are equivalent to 155/80R13?
Within 3 percent of the same diameter on the same 13-inch wheel: 175/70R13 (-0.5%), 145/80R13 (-2.8%), 165/80R13 (+2.8%); on a 14-inch wheel: 175/65R14 (+0.8%), 165/65R14 (-1.4%). The percentage is the diameter change, which is also your speedometer error.
Can I use 165/80R13 instead of 155/80R13?
Dimensionally yes: 165/80R13 is 2.8% taller (+16 mm) and 10 mm wider, and at a true 60 mph the speedometer would read 58.4 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.