GarageCalc What 265/40R22 means
265 is the section width in millimeters (10.4 in). 40 is the aspect ratio: the sidewall is 40 percent of the width, so 265 × 0.40 = 106 mm (4.2 in). R is radial construction, and 22 is the wheel diameter in inches (559 mm). Stack two sidewalls on the wheel and you get the overall diameter: 559 + 2 × 106 = 771 mm, or 30.3 in.
A full marking adds a load index and speed rating after the size, for example 265/40R22 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 265/40R22
No common 23-inch size stays within 3 percent of 30.3 in. Going down one size, 265/45R21 is +0.1% with a taller 119 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 265/40R22 tire?
30.3 inches (771 mm) in overall diameter: the 22-inch wheel (559 mm) plus two 106 mm sidewalls. Real tires land within about 1 to 2 percent of that depending on brand, tread depth and pressure.
What is 265/40R22 in inches?
30.3 x 10.4 R22: 30.3 inches tall, 10.4 inches wide, on a 22-inch wheel. The sidewall is 4.2 inches and the circumference is 95.3 inches, so the tire turns 665 times per mile.
What tire sizes are equivalent to 265/40R22?
Within 3 percent of the same diameter on the same 22-inch wheel: 275/40R22 (+1.0%), 285/35R22 (-1.6%), 285/40R22 (+2.1%); on a 21-inch wheel: 265/45R21 (+0.1%), 255/45R21 (-1.0%). The percentage is the diameter change, which is also your speedometer error.
Can I use 275/40R22 instead of 265/40R22?
Dimensionally yes: 275/40R22 is 1.0% taller (+8 mm) and 10 mm wider, and at a true 60 mph the speedometer would read 59.4 mph. The extra width needs about 0.20 in of clearance on each side of the tire and a rim width that suits 275 mm.