325/35R21 tire size in inches

A 325/35R21 tire measures

30.0" tall × 12.8" wide

4.48" sidewall on a 21" wheel. 673 revolutions per mile.

325/35R21 means a tire 325 mm wide, with sidewalls 35% as tall as the tire is wide (114 mm), radial construction (R), for a 21 inch wheel.

30.0"21" rim4.5"12.8" wide
325/35R21: 30.0 inches tall, 12.8 inches wide, on a 21 inch rim, drawn to scale

325/35R21 specs

Overall diameter (height)29.96 inches (761 mm)
Section width12.80 inches (325 mm)
Sidewall height4.48 inches (114 mm)
Wheel (rim) diameter21 inches
Circumference94.1 inches (2,390 mm)
Revolutions per mile673
Revolutions per kilometer418
Approximate rim width10.5" to 12.0"
In inches (flotation style)30.0x12.8R21
Aspect ratio35%

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 325/35R21 on a 21" wheel

These 21" sizes are within 3% of 325/35R21's overall diameter, the range most tire shops treat as interchangeable.

SizeDiameterWidthDifferenceReal speed at 60
285/40R2129.98"11.22"+0.1%60.0 mphCompare
255/45R2130.04"10.04"+0.3%60.2 mphCompare
225/50R2129.86"8.86"−0.3%59.8 mphCompare
335/35R2130.23"13.19"+0.9%60.6 mphCompare
245/45R2129.68"9.65"−0.9%59.4 mphCompare
315/35R2129.68"12.40"−0.9%59.4 mphCompare
235/50R2130.25"9.25"+1.0%60.6 mphCompare
275/40R2129.66"10.83"−1.0%59.4 mphCompare
295/40R2130.29"11.61"+1.1%60.7 mphCompare
265/45R2130.39"10.43"+1.4%60.9 mphCompare
345/35R2130.51"13.58"+1.8%61.1 mphCompare
305/35R2129.41"12.01"−1.8%58.9 mphCompare

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

SizeWheelDiameterDifference
235/70R1717"29.95"0.0%Compare
295/60R1616"29.94"−0.1%Compare
275/60R1717"29.99"+0.1%Compare
315/40R2020"29.92"−0.1%Compare
30x9.50R1515"30.00"+0.1%Compare
335/30R2222"29.91"−0.1%Compare
215/65R1919"30.00"+0.2%Compare
305/25R2424"30.00"+0.2%Compare
275/55R1818"29.91"−0.2%Compare
305/50R1818"30.01"+0.2%Compare
255/30R2424"30.02"+0.2%Compare
235/65R1818"30.03"+0.2%Compare

One size up or down

Compare 325/35R21 with another size

With 335/35R21 tires, when your speedometer says 60 mph you are really going

60.6 mph

335/35R21 is +0.28 inches (+0.9%) in overall diameter. That is within the 3% most shops and makers allow.

325/35R21335/35R21Difference%
Overall diameter29.96"30.23"+0.28"+0.9%
Section width12.80"13.19"+0.39"+3.1%
Sidewall height4.48"4.62"+0.14"+3.1%
Circumference94.11"94.98"+0.87"+0.9%
Revolutions per mile673.2667.1−6.1−0.9%

Questions

How tall is a 325/35R21 tire?
A 325/35R21 tire is 30.0 inches tall (761 mm), calculated from the size. It is 12.8 inches wide with 4.5 inches sidewalls. Real tires vary by a few tenths of an inch between brands and tread patterns.
What does 325/35R21 mean?
325/35R21 means a tire 325 mm wide, with sidewalls 35% as tall as the tire is wide (114 mm), radial construction (R), for a 21 inch wheel.
How many revolutions per mile does a 325/35R21 tire make?
About 673 revolutions per mile, based on a circumference of 94.1 inches. Under load the tire flattens slightly, so the maker's published figure is usually a little higher.
What rim width fits a 325/35R21 tire?
Roughly 10.5" to 12.0". Check the tire maker's approved rim range for the exact model before buying wheels.
Can I use 285/40R21 instead of 325/35R21?
285/40R21 is +0.02 inches (+0.1%) 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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