335/40R21 tire size in inches

A 335/40R21 tire measures

31.6" tall × 13.2" wide

5.28" sidewall on a 21" wheel. 639 revolutions per mile.

335/40R21 means a tire 335 mm wide, with sidewalls 40% as tall as the tire is wide (134 mm), radial construction (R), for a 21 inch wheel.

31.6"21" rim5.3"13.2" wide
335/40R21: 31.6 inches tall, 13.2 inches wide, on a 21 inch rim, drawn to scale

335/40R21 specs

Overall diameter (height)31.55 inches (801 mm)
Section width13.19 inches (335 mm)
Sidewall height5.28 inches (134 mm)
Wheel (rim) diameter21 inches
Circumference99.1 inches (2,518 mm)
Revolutions per mile639
Revolutions per kilometer397
Approximate rim width11.0" to 12.5"
In inches (flotation style)31.6x13.2R21
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 335/40R21 on a 21" wheel

These 21" sizes are within 3% of 335/40R21's overall diameter, the range most tire shops treat as interchangeable.

SizeDiameterWidthDifferenceReal speed at 60
245/55R2131.61"9.65"+0.2%60.1 mphCompare
295/45R2131.45"11.61"−0.3%59.8 mphCompare
265/50R2131.43"10.43"−0.4%59.8 mphCompare
305/45R2131.81"12.01"+0.8%60.5 mphCompare
275/50R2131.83"10.83"+0.9%60.5 mphCompare
325/40R2131.24"12.80"−1.0%59.4 mphCompare
345/40R2131.87"13.58"+1.0%60.6 mphCompare
235/55R2131.18"9.25"−1.2%59.3 mphCompare
285/45R2131.10"11.22"−1.4%59.1 mphCompare
255/55R2132.04"10.04"+1.6%60.9 mphCompare
255/50R2131.04"10.04"−1.6%59.0 mphCompare
315/45R2132.16"12.40"+1.9%61.2 mphCompare

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

SizeWheelDiameterDifference
265/65R1818"31.56"0.0%Compare
245/65R1919"31.54"0.0%Compare
245/60R2020"31.57"+0.1%Compare
275/35R2424"31.58"+0.1%Compare
355/45R1919"31.58"+0.1%Compare
265/60R1919"31.52"−0.1%Compare
285/65R1717"31.59"+0.1%Compare
225/65R2020"31.52"−0.1%Compare
325/45R2020"31.52"−0.1%Compare
345/35R2222"31.51"−0.1%Compare
245/70R1818"31.50"−0.1%Compare
265/70R1717"31.61"+0.2%Compare

One size up or down

Compare 335/40R21 with another size

With 345/40R21 tires, when your speedometer says 60 mph you are really going

60.6 mph

345/40R21 is +0.31 inches (+1.0%) in overall diameter. That is within the 3% most shops and makers allow.

335/40R21345/40R21Difference%
Overall diameter31.55"31.87"+0.31"+1.0%
Section width13.19"13.58"+0.39"+3.0%
Sidewall height5.28"5.43"+0.16"+3.0%
Circumference99.12"100.11"+0.99"+1.0%
Revolutions per mile639.2632.9−6.3−1.0%

Questions

How tall is a 335/40R21 tire?
A 335/40R21 tire is 31.6 inches tall (801 mm), calculated from the size. It is 13.2 inches wide with 5.3 inches sidewalls. Real tires vary by a few tenths of an inch between brands and tread patterns.
What does 335/40R21 mean?
335/40R21 means a tire 335 mm wide, with sidewalls 40% as tall as the tire is wide (134 mm), radial construction (R), for a 21 inch wheel.
How many revolutions per mile does a 335/40R21 tire make?
About 639 revolutions per mile, based on a circumference of 99.1 inches. Under load the tire flattens slightly, so the maker's published figure is usually a little higher.
What rim width fits a 335/40R21 tire?
Roughly 11.0" to 12.5". Check the tire maker's approved rim range for the exact model before buying wheels.
Can I use 245/55R21 instead of 335/40R21?
245/55R21 is +0.06 inches (+0.2%) 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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