245/45R20 tire size in inches

A 245/45R20 tire measures

28.7" tall × 9.6" wide

4.34" sidewall on a 20" wheel. 703 revolutions per mile.

245/45R20 means a tire 245 mm wide, with sidewalls 45% as tall as the tire is wide (110 mm), radial construction (R), for a 20 inch wheel.

28.7"20" rim4.3"9.6" wide
245/45R20: 28.7 inches tall, 9.6 inches wide, on a 20 inch rim, drawn to scale

245/45R20 specs

Overall diameter (height)28.68 inches (729 mm)
Section width9.65 inches (245 mm)
Sidewall height4.34 inches (110 mm)
Wheel (rim) diameter20 inches
Circumference90.1 inches (2,289 mm)
Revolutions per mile703
Revolutions per kilometer437
Approximate rim width8.0" to 9.5"
In inches (flotation style)28.7x9.6R20
Aspect ratio45%

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 245/45R20 on a 20" wheel

These 20" sizes are within 3% of 245/45R20's overall diameter, the range most tire shops treat as interchangeable.

SizeDiameterWidthDifferenceReal speed at 60
315/35R2028.68"12.40"0.0%60.0 mphCompare
275/40R2028.66"10.83"−0.1%60.0 mphCompare
225/50R2028.86"8.86"+0.6%60.4 mphCompare
215/50R2028.46"8.46"−0.8%59.5 mphCompare
305/35R2028.41"12.01"−1.0%59.4 mphCompare
325/35R2028.96"12.80"+1.0%60.6 mphCompare
285/40R2028.98"11.22"+1.0%60.6 mphCompare
355/30R2028.39"13.98"−1.0%59.4 mphCompare
265/40R2028.35"10.43"−1.2%59.3 mphCompare
255/45R2029.04"10.04"+1.2%60.7 mphCompare
235/45R2028.33"9.25"−1.2%59.3 mphCompare
345/30R2028.15"13.58"−1.9%58.9 mphCompare

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

SizeWheelDiameterDifference
205/60R1919"28.69"0.0%Compare
325/30R2121"28.68"0.0%Compare
215/75R1616"28.70"+0.1%Compare
245/50R1919"28.65"−0.1%Compare
245/40R2121"28.72"+0.1%Compare
205/85R1515"28.72"+0.1%Compare
235/85R1313"28.73"+0.2%Compare
285/30R2222"28.73"+0.2%Compare
225/60R1818"28.63"−0.2%Compare
225/55R1919"28.74"+0.2%Compare
275/45R1919"28.74"+0.2%Compare
195/70R1818"28.75"+0.2%Compare

One size up or down

Compare 245/45R20 with another size

With 255/45R20 tires, when your speedometer says 60 mph you are really going

60.7 mph

255/45R20 is +0.35 inches (+1.2%) in overall diameter. That is within the 3% most shops and makers allow.

245/45R20255/45R20Difference%
Overall diameter28.68"29.04"+0.35"+1.2%
Section width9.65"10.04"+0.39"+4.1%
Sidewall height4.34"4.52"+0.18"+4.1%
Circumference90.10"91.22"+1.11"+1.2%
Revolutions per mile703.2694.6−8.6−1.2%

Questions

How tall is a 245/45R20 tire?
A 245/45R20 tire is 28.7 inches tall (729 mm), calculated from the size. It is 9.6 inches wide with 4.3 inches sidewalls. Real tires vary by a few tenths of an inch between brands and tread patterns.
What does 245/45R20 mean?
245/45R20 means a tire 245 mm wide, with sidewalls 45% as tall as the tire is wide (110 mm), radial construction (R), for a 20 inch wheel.
How many revolutions per mile does a 245/45R20 tire make?
About 703 revolutions per mile, based on a circumference of 90.1 inches. Under load the tire flattens slightly, so the maker's published figure is usually a little higher.
What rim width fits a 245/45R20 tire?
Roughly 8.0" to 9.5". Check the tire maker's approved rim range for the exact model before buying wheels.
Can I use 315/35R20 instead of 245/45R20?
315/35R20 is 0.00 inches (0.0%) in overall diameter, so at an indicated 60 mph you would be doing 60.0 mph. Differences under 3% are usually fine, but check clearance, load index and your vehicle's placard.

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