GarageCalc What 185/70R14 means
185 is the section width in millimeters (7.3 in). 70 is the aspect ratio: the sidewall is 70 percent of the width, so 185 × 0.70 = 130 mm (5.1 in). R is radial construction, and 14 is the wheel diameter in inches (356 mm). Stack two sidewalls on the wheel and you get the overall diameter: 356 + 2 × 130 = 615 mm, or 24.2 in.
A full marking adds a load index and speed rating after the size, for example 185/70R14 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 185/70R14
Going up one wheel size, the closest match is 195/60R15 at +0.1% diameter with a 117 mm sidewall instead of 130 mm. No common 13-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 185/70R14 tire?
24.2 inches (615 mm) in overall diameter: the 14-inch wheel (356 mm) plus two 130 mm sidewalls. Real tires land within about 1 to 2 percent of that depending on brand, tread depth and pressure.
What is 185/70R14 in inches?
24.2 x 7.3 R14: 24.2 inches tall, 7.3 inches wide, on a 14-inch wheel. The sidewall is 5.1 inches and the circumference is 76.0 inches, so the tire turns 834 times per mile.
What tire sizes are equivalent to 185/70R14?
Within 3 percent of the same diameter on the same 14-inch wheel: 195/65R14 (-0.9%), 175/70R14 (-2.3%), 195/70R14 (+2.3%); on a 15-inch wheel: 195/60R15 (+0.1%), 175/65R15 (-1.0%). The percentage is the diameter change, which is also your speedometer error.
Can I use 195/65R14 instead of 185/70R14?
Dimensionally yes: 195/65R14 is 0.9% shorter (-6 mm) and 10 mm wider, and at a true 60 mph the speedometer would read 60.5 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.