GarageCalc What 215/70R15 means
215 is the section width in millimeters (8.5 in). 70 is the aspect ratio: the sidewall is 70 percent of the width, so 215 × 0.70 = 151 mm (5.9 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 × 151 = 682 mm, or 26.9 in.
A full marking adds a load index and speed rating after the size, for example 215/70R15 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 215/70R15
Going up one wheel size, the closest match is 215/65R16 at +0.6% diameter with a 140 mm sidewall instead of 151 mm. No common 14-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 215/70R15 tire?
26.9 inches (682 mm) in overall diameter: the 15-inch wheel (381 mm) plus two 151 mm sidewalls. Real tires land within about 1 to 2 percent of that depending on brand, tread depth and pressure.
What is 215/70R15 in inches?
26.9 x 8.5 R15: 26.9 inches tall, 8.5 inches wide, on a 15-inch wheel. The sidewall is 5.9 inches and the circumference is 84.4 inches, so the tire turns 751 times per mile.
What tire sizes are equivalent to 215/70R15?
Within 3 percent of the same diameter on the same 15-inch wheel: 205/75R15 (+1.0%), 205/70R15 (-2.1%), 225/70R15 (+2.1%); on a 16-inch wheel: 215/65R16 (+0.6%), 225/60R16 (-0.8%). The percentage is the diameter change, which is also your speedometer error.
Can I use 225/70R15 instead of 215/70R15?
Dimensionally yes: 225/70R15 is 2.1% taller (+14 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 225 mm.