GarageCalc What 175/70R13 means
175 is the section width in millimeters (6.9 in). 70 is the aspect ratio: the sidewall is 70 percent of the width, so 175 × 0.70 = 123 mm (4.8 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 × 123 = 575 mm, or 22.6 in.
A full marking adds a load index and speed rating after the size, for example 175/70R13 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 175/70R13
Going up one wheel size, the closest match is 185/60R14 at +0.4% diameter with a 111 mm sidewall instead of 123 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 175/70R13 tire?
22.6 inches (575 mm) in overall diameter: the 13-inch wheel (330 mm) plus two 123 mm sidewalls. Real tires land within about 1 to 2 percent of that depending on brand, tread depth and pressure.
What is 175/70R13 in inches?
22.6 x 6.9 R13: 22.6 inches tall, 6.9 inches wide, on a 13-inch wheel. The sidewall is 4.8 inches and the circumference is 71.1 inches, so the tire turns 891 times per mile.
What tire sizes are equivalent to 175/70R13?
Within 3 percent of the same diameter on the same 13-inch wheel: 155/80R13 (+0.5%), 165/70R13 (-2.4%), 185/70R13 (+2.4%); on a 14-inch wheel: 185/60R14 (+0.4%), 165/65R14 (-0.9%). The percentage is the diameter change, which is also your speedometer error.
Can I use 185/70R13 instead of 175/70R13?
Dimensionally yes: 185/70R13 is 2.4% taller (+14 mm) and 10 mm wider, and at a true 60 mph the speedometer would read 58.6 mph. The extra width needs about 0.20 in of clearance on each side of the tire and a rim width that suits 185 mm.