GarageCalc What 265/30R19 means
265 is the section width in millimeters (10.4 in). 30 is the aspect ratio: the sidewall is 30 percent of the width, so 265 × 0.30 = 80 mm (3.1 in). R is radial construction, and 19 is the wheel diameter in inches (483 mm). Stack two sidewalls on the wheel and you get the overall diameter: 483 + 2 × 80 = 642 mm, or 25.3 in.
A full marking adds a load index and speed rating after the size, for example 265/30R19 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 265/30R19
Going up one wheel size, the closest match is 245/30R20 at +2.1% diameter with a 74 mm sidewall instead of 80 mm. Going down one size, 265/35R18 is +0.2% with a taller 93 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 265/30R19 tire?
25.3 inches (642 mm) in overall diameter: the 19-inch wheel (483 mm) plus two 80 mm sidewalls. Real tires land within about 1 to 2 percent of that depending on brand, tread depth and pressure.
What is 265/30R19 in inches?
25.3 x 10.4 R19: 25.3 inches tall, 10.4 inches wide, on a 19-inch wheel. The sidewall is 3.1 inches and the circumference is 79.4 inches, so the tire turns 798 times per mile.
What tire sizes are equivalent to 265/30R19?
Within 3 percent of the same diameter on the same 19-inch wheel: 255/30R19 (-0.9%), 275/30R19 (+0.9%), 285/30R19 (+1.9%); on a 20-inch wheel: 245/30R20 (+2.1%); on an 18-inch wheel: 265/35R18 (+0.2%), 255/35R18 (-0.9%). The percentage is the diameter change, which is also your speedometer error.
Can I use 275/30R19 instead of 265/30R19?
Dimensionally yes: 275/30R19 is 0.9% taller (+6 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.