GarageCalc What 245/70R16 means
245 is the section width in millimeters (9.6 in). 70 is the aspect ratio: the sidewall is 70 percent of the width, so 245 × 0.70 = 172 mm (6.8 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 × 172 = 749 mm, or 29.5 in.
A full marking adds a load index and speed rating after the size, for example 245/70R16 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 245/70R16
Going up one wheel size, the closest match is 245/65R17 at +0.1% diameter with a 159 mm sidewall instead of 172 mm. Going down one size, 265/70R15 is +0.3% with a taller 186 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 245/70R16 tire?
29.5 inches (749 mm) in overall diameter: the 16-inch wheel (406 mm) plus two 172 mm sidewalls. Real tires land within about 1 to 2 percent of that depending on brand, tread depth and pressure.
What is 245/70R16 in inches?
29.5 x 9.6 R16: 29.5 inches tall, 9.6 inches wide, on a 16-inch wheel. The sidewall is 6.8 inches and the circumference is 92.7 inches, so the tire turns 684 times per mile.
What tire sizes are equivalent to 245/70R16?
Within 3 percent of the same diameter on the same 16-inch wheel: 225/75R16 (-0.7%), 235/75R16 (+1.3%), 255/65R16 (-1.5%); on a 17-inch wheel: 245/65R17 (+0.1%), 235/70R17 (+1.5%); on a 15-inch wheel: 265/70R15 (+0.3%), 255/70R15 (-1.5%). The percentage is the diameter change, which is also your speedometer error.
Can I use 255/65R16 instead of 245/70R16?
Dimensionally yes: 255/65R16 is 1.5% shorter (-12 mm) and 10 mm wider, and at a true 60 mph the speedometer would read 60.9 mph. The extra width needs about 0.20 in of clearance on each side of the tire and a rim width that suits 255 mm.