GarageCalc What 245/60R20 means
245 is the section width in millimeters (9.6 in). 60 is the aspect ratio: the sidewall is 60 percent of the width, so 245 × 0.60 = 147 mm (5.8 in). R is radial construction, and 20 is the wheel diameter in inches (508 mm). Stack two sidewalls on the wheel and you get the overall diameter: 508 + 2 × 147 = 802 mm, or 31.6 in.
A full marking adds a load index and speed rating after the size, for example 245/60R20 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 245/60R20
Going up one wheel size, the closest match is 255/50R21 at -1.7% diameter with a 128 mm sidewall instead of 147 mm. No common 19-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.
Which cars come with 245/60R20
Typical factory fitments include Toyota 4Runner Limited (2010 on). Tire size changes with trim and wheel option, so confirm on the door-jamb placard before buying.
Frequently asked questions
How tall is a 245/60R20 tire?
31.6 inches (802 mm) in overall diameter: the 20-inch wheel (508 mm) plus two 147 mm sidewalls. Real tires land within about 1 to 2 percent of that depending on brand, tread depth and pressure.
What is 245/60R20 in inches?
31.6 x 9.6 R20: 31.6 inches tall, 9.6 inches wide, on a 20-inch wheel. The sidewall is 5.8 inches and the circumference is 99.2 inches, so the tire turns 639 times per mile.
What tire sizes are equivalent to 245/60R20?
Within 3 percent of the same diameter on the same 20-inch wheel: 255/55R20 (-1.7%), 265/60R20 (+3.0%); on a 21-inch wheel: 255/50R21 (-1.7%). The percentage is the diameter change, which is also your speedometer error.
Can I use 255/55R20 instead of 245/60R20?
Dimensionally yes: 255/55R20 is 1.7% shorter (-14 mm) and 10 mm wider, and at a true 60 mph the speedometer would read 61.0 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.