355/25R21 tire size in inches

A 355/25R21 tire measures

28.0" tall × 14.0" wide

3.49" sidewall on a 21" wheel. 721 revolutions per mile.

355/25R21 means a tire 355 mm wide, with sidewalls 25% as tall as the tire is wide (89 mm), radial construction (R), for a 21 inch wheel.

28.0"21" rim3.5"14.0" wide
355/25R21: 28.0 inches tall, 14.0 inches wide, on a 21 inch rim, drawn to scale

355/25R21 specs

Overall diameter (height)27.99 inches (711 mm)
Section width13.98 inches (355 mm)
Sidewall height3.49 inches (89 mm)
Wheel (rim) diameter21 inches
Circumference87.9 inches (2,233 mm)
Revolutions per mile721
Revolutions per kilometer448
Approximate rim width11.5" to 13.0"
In inches (flotation style)28.0x14.0R21
Aspect ratio25%

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 355/25R21 on a 21" wheel

These 21" sizes are within 3% of 355/25R21's overall diameter, the range most tire shops treat as interchangeable.

SizeDiameterWidthDifferenceReal speed at 60
295/30R2127.97"11.61"−0.1%60.0 mphCompare
255/35R2128.03"10.04"+0.1%60.1 mphCompare
225/40R2128.09"8.86"+0.4%60.2 mphCompare
345/25R2127.79"13.58"−0.7%59.6 mphCompare
305/30R2128.20"12.01"+0.8%60.5 mphCompare
245/35R2127.75"9.65"−0.8%59.5 mphCompare
285/30R2127.73"11.22"−0.9%59.5 mphCompare
265/35R2128.30"10.43"+1.1%60.7 mphCompare
335/25R2127.59"13.19"−1.4%59.2 mphCompare
235/40R2128.40"9.25"+1.5%60.9 mphCompare
315/30R2128.44"12.40"+1.6%61.0 mphCompare
275/30R2127.50"10.83"−1.8%58.9 mphCompare

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

SizeWheelDiameterDifference
275/60R1515"27.99"0.0%Compare
195/65R1818"27.98"0.0%Compare
285/40R1919"27.98"0.0%Compare
215/65R1717"28.00"+0.1%Compare
225/45R2020"27.97"−0.1%Compare
305/25R2222"28.00"+0.1%Compare
325/35R1919"27.96"−0.1%Compare
235/70R1515"27.95"−0.1%Compare
255/30R2222"28.02"+0.1%Compare
235/65R1616"28.03"+0.1%Compare
255/40R2020"28.03"+0.2%Compare
255/45R1919"28.04"+0.2%Compare

One size up or down

Compare 355/25R21 with another size

With 295/30R21 tires, when your speedometer says 60 mph you are really going

60.0 mph

295/30R21 is −0.02 inches (−0.1%) in overall diameter. That is within the 3% most shops and makers allow.

355/25R21295/30R21Difference%
Overall diameter27.99"27.97"−0.02"−0.1%
Section width13.98"11.61"−2.36"−16.9%
Sidewall height3.49"3.48"−0.01"−0.3%
Circumference87.93"87.87"−0.06"−0.1%
Revolutions per mile720.6721.1+0.5+0.1%

Questions

How tall is a 355/25R21 tire?
A 355/25R21 tire is 28.0 inches tall (711 mm), calculated from the size. It is 14.0 inches wide with 3.5 inches sidewalls. Real tires vary by a few tenths of an inch between brands and tread patterns.
What does 355/25R21 mean?
355/25R21 means a tire 355 mm wide, with sidewalls 25% as tall as the tire is wide (89 mm), radial construction (R), for a 21 inch wheel.
How many revolutions per mile does a 355/25R21 tire make?
About 721 revolutions per mile, based on a circumference of 87.9 inches. Under load the tire flattens slightly, so the maker's published figure is usually a little higher.
What rim width fits a 355/25R21 tire?
Roughly 11.5" to 13.0". Check the tire maker's approved rim range for the exact model before buying wheels.
Can I use 295/30R21 instead of 355/25R21?
295/30R21 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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