GarageCalc What 215/55R16 means
215 is the section width in millimeters (8.5 in). 55 is the aspect ratio: the sidewall is 55 percent of the width, so 215 × 0.55 = 118 mm (4.7 in). R is radial construction, and 16 is the wheel diameter in inches (406 mm). Stack two sidewalls on the wheel and you get the overall diameter: 406 + 2 × 118 = 643 mm, or 25.3 in.
A full marking adds a load index and speed rating after the size, for example 215/55R16 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 215/55R16
Going up one wheel size, the closest match is 235/45R17 at +0.1% diameter with a 106 mm sidewall instead of 118 mm. Going down one size, 215/60R15 is -0.6% with a taller 129 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 215/55R16 tire?
25.3 inches (643 mm) in overall diameter: the 16-inch wheel (406 mm) plus two 118 mm sidewalls. Real tires land within about 1 to 2 percent of that depending on brand, tread depth and pressure.
What is 215/55R16 in inches?
25.3 x 8.5 R16: 25.3 inches tall, 8.5 inches wide, on a 16-inch wheel. The sidewall is 4.7 inches and the circumference is 79.5 inches, so the tire turns 797 times per mile.
What tire sizes are equivalent to 215/55R16?
Within 3 percent of the same diameter on the same 16-inch wheel: 195/60R16 (-0.4%), 205/60R16 (+1.5%), 205/55R16 (-1.7%); on a 17-inch wheel: 235/45R17 (+0.1%), 215/50R17 (+0.6%); on a 15-inch wheel: 215/60R15 (-0.6%), 205/65R15 (+0.7%). The percentage is the diameter change, which is also your speedometer error.
Can I use 225/55R16 instead of 215/55R16?
Dimensionally yes: 225/55R16 is 1.7% taller (+11 mm) and 10 mm wider, and at a true 60 mph the speedometer would read 59.0 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.