GarageCalc What 235/50R17 means
235 is the section width in millimeters (9.3 in). 50 is the aspect ratio: the sidewall is 50 percent of the width, so 235 × 0.50 = 118 mm (4.6 in). R is radial construction, and 17 is the wheel diameter in inches (432 mm). Stack two sidewalls on the wheel and you get the overall diameter: 432 + 2 × 118 = 667 mm, or 26.3 in.
A full marking adds a load index and speed rating after the size, for example 235/50R17 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 235/50R17
Going up one wheel size, the closest match is 235/45R18 at +0.3% diameter with a 106 mm sidewall instead of 118 mm. Going down one size, 215/60R16 is -0.4% 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 235/50R17 tire?
26.3 inches (667 mm) in overall diameter: the 17-inch wheel (432 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 235/50R17 in inches?
26.3 x 9.3 R17: 26.3 inches tall, 9.3 inches wide, on a 17-inch wheel. The sidewall is 4.6 inches and the circumference is 82.5 inches, so the tire turns 768 times per mile.
What tire sizes are equivalent to 235/50R17?
Within 3 percent of the same diameter on the same 17-inch wheel: 215/55R17 (+0.2%), 255/45R17 (-0.8%), 225/50R17 (-1.5%); on an 18-inch wheel: 235/45R18 (+0.3%), 215/50R18 (+0.8%); on a 16-inch wheel: 215/60R16 (-0.4%), 225/60R16 (+1.4%). The percentage is the diameter change, which is also your speedometer error.
Can I use 245/45R17 instead of 235/50R17?
Dimensionally yes: 245/45R17 is 2.2% shorter (-15 mm) and 10 mm wider, and at a true 60 mph the speedometer would read 61.3 mph. The extra width needs about 0.20 in of clearance on each side of the tire and a rim width that suits 245 mm.