305/40R19 tire size in inches

A 305/40R19 tire measures

28.6" tall × 12.0" wide

4.80" sidewall on a 19" wheel. 705 revolutions per mile.

305/40R19 means a tire 305 mm wide, with sidewalls 40% as tall as the tire is wide (122 mm), radial construction (R), for a 19 inch wheel.

28.6"19" rim4.8"12.0" wide
305/40R19: 28.6 inches tall, 12.0 inches wide, on a 19 inch rim, drawn to scale

305/40R19 specs

Overall diameter (height)28.61 inches (727 mm)
Section width12.01 inches (305 mm)
Sidewall height4.80 inches (122 mm)
Wheel (rim) diameter19 inches
Circumference89.9 inches (2,283 mm)
Revolutions per mile705
Revolutions per kilometer438
Approximate rim width10.0" to 11.5"
In inches (flotation style)28.6x12.0R19
Aspect ratio40%

Calculated from the size. Real tires differ by brand, model and tread depth, typically by a few tenths of an inch.

Sizes that can replace 305/40R19 on a 19" wheel

These 19" sizes are within 3% of 305/40R19's overall diameter, the range most tire shops treat as interchangeable.

SizeDiameterWidthDifferenceReal speed at 60
245/50R1928.65"9.65"+0.1%60.1 mphCompare
205/60R1928.69"8.07"+0.3%60.2 mphCompare
345/35R1928.51"13.58"−0.3%59.8 mphCompare
225/55R1928.74"8.86"+0.5%60.3 mphCompare
275/45R1928.74"10.83"+0.5%60.3 mphCompare
355/35R1928.78"13.98"+0.6%60.4 mphCompare
265/45R1928.39"10.43"−0.8%59.5 mphCompare
215/55R1928.31"8.46"−1.0%59.4 mphCompare
295/40R1928.29"11.61"−1.1%59.3 mphCompare
315/40R1928.92"12.40"+1.1%60.7 mphCompare
235/50R1928.25"9.25"−1.2%59.3 mphCompare
335/35R1928.23"13.19"−1.3%59.2 mphCompare

Same height on other wheel sizes (plus and minus sizing)

SizeWheelDiameterDifference
265/70R1414"28.61"0.0%Compare
245/55R1818"28.61"0.0%Compare
295/50R1717"28.61"0.0%Compare
335/25R2222"28.59"0.0%Compare
225/60R1818"28.63"+0.1%Compare
275/35R2121"28.58"−0.1%Compare
245/60R1717"28.57"−0.1%Compare
265/65R1515"28.56"−0.2%Compare
275/40R2020"28.66"+0.2%Compare
335/40R1818"28.55"−0.2%Compare
215/80R1515"28.54"−0.2%Compare
245/65R1616"28.54"−0.2%Compare

One size up or down

Compare 305/40R19 with another size

With 315/40R19 tires, when your speedometer says 60 mph you are really going

60.7 mph

315/40R19 is +0.31 inches (+1.1%) in overall diameter. That is within the 3% most shops and makers allow.

305/40R19315/40R19Difference%
Overall diameter28.61"28.92"+0.31"+1.1%
Section width12.01"12.40"+0.39"+3.3%
Sidewall height4.80"4.96"+0.16"+3.3%
Circumference89.87"90.86"+0.99"+1.1%
Revolutions per mile705.0697.3−7.7−1.1%

Questions

How tall is a 305/40R19 tire?
A 305/40R19 tire is 28.6 inches tall (727 mm), calculated from the size. It is 12.0 inches wide with 4.8 inches sidewalls. Real tires vary by a few tenths of an inch between brands and tread patterns.
What does 305/40R19 mean?
305/40R19 means a tire 305 mm wide, with sidewalls 40% as tall as the tire is wide (122 mm), radial construction (R), for a 19 inch wheel.
How many revolutions per mile does a 305/40R19 tire make?
About 705 revolutions per mile, based on a circumference of 89.9 inches. Under load the tire flattens slightly, so the maker's published figure is usually a little higher.
What rim width fits a 305/40R19 tire?
Roughly 10.0" to 11.5". Check the tire maker's approved rim range for the exact model before buying wheels.
Can I use 245/50R19 instead of 305/40R19?
245/50R19 is +0.04 inches (+0.1%) in overall diameter, so at an indicated 60 mph you would be doing 60.1 mph. Differences under 3% are usually fine, but check clearance, load index and your vehicle's placard.

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