GarageCalc What 195/70R15 means
195 is the section width in millimeters (7.7 in). 70 is the aspect ratio: the sidewall is 70 percent of the width, so 195 × 0.70 = 137 mm (5.4 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 × 137 = 654 mm, or 25.7 in.
A full marking adds a load index and speed rating after the size, for example 195/70R15 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 195/70R15
Going up one wheel size, the closest match is 205/60R16 at -0.2% diameter with a 123 mm sidewall instead of 137 mm. Going down one size, 215/70R14 is +0.4% with a taller 151 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 195/70R15 tire?
25.7 inches (654 mm) in overall diameter: the 15-inch wheel (381 mm) plus two 137 mm sidewalls. Real tires land within about 1 to 2 percent of that depending on brand, tread depth and pressure.
What is 195/70R15 in inches?
25.7 x 7.7 R15: 25.7 inches tall, 7.7 inches wide, on a 15-inch wheel. The sidewall is 5.4 inches and the circumference is 80.9 inches, so the tire turns 783 times per mile.
What tire sizes are equivalent to 195/70R15?
Within 3 percent of the same diameter on the same 15-inch wheel: 205/65R15 (-1.0%), 215/65R15 (+1.0%), 205/70R15 (+2.1%); on a 16-inch wheel: 205/60R16 (-0.2%), 215/60R16 (+1.6%); on a 14-inch wheel: 215/70R14 (+0.4%), 205/70R14 (-1.7%). The percentage is the diameter change, which is also your speedometer error.
Can I use 205/65R15 instead of 195/70R15?
Dimensionally yes: 205/65R15 is 1.0% shorter (-7 mm) and 10 mm wider, and at a true 60 mph the speedometer would read 60.6 mph. The extra width needs about 0.20 in of clearance on each side of the tire and a rim width that suits 205 mm.