345/55R21 tire size in inches
A 345/55R21 tire measures
35.9" tall × 13.6" wide
7.47" sidewall on a 21" wheel. 561 revolutions per mile.
345/55R21 means a tire 345 mm wide, with sidewalls 55% as tall as the tire is wide (190 mm), radial construction (R), for a 21 inch wheel.
345/55R21 specs
| Overall diameter (height) | 35.94 inches (913 mm) |
|---|---|
| Section width | 13.58 inches (345 mm) |
| Sidewall height | 7.47 inches (190 mm) |
| Wheel (rim) diameter | 21 inches |
| Circumference | 112.9 inches (2,868 mm) |
| Revolutions per mile | 561 |
| Revolutions per kilometer | 349 |
| Approximate rim width | 10.0" to 11.5" |
| In inches (flotation style) | 35.9x13.6R21 |
| Aspect ratio | 55% |
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 345/55R21 on a 21" wheel
These 21" sizes are within 3% of 345/55R21's overall diameter, the range most tire shops treat as interchangeable.
| Size | Diameter | Width | Difference | Real speed at 60 | |
|---|---|---|---|---|---|
| 335/55R21 | 35.51" | 13.19" | −1.2% | 59.3 mph | Compare |
| 325/55R21 | 35.07" | 12.80" | −2.4% | 58.6 mph | Compare |
| 355/50R21 | 34.98" | 13.98" | −2.7% | 58.4 mph | Compare |
Same height on other wheel sizes (plus and minus sizing)
| Size | Wheel | Diameter | Difference | |
|---|---|---|---|---|
| 325/70R18 | 18" | 35.91" | −0.1% | Compare |
| 355/50R22 | 22" | 35.98" | +0.1% | Compare |
| 335/60R20 | 20" | 35.83" | −0.3% | Compare |
| 355/60R19 | 19" | 35.77" | −0.5% | Compare |
| 295/85R16 | 16" | 35.74" | −0.5% | Compare |
| 315/55R22 | 22" | 35.64" | −0.8% | Compare |
| 325/65R19 | 19" | 35.63" | −0.9% | Compare |
| 305/65R20 | 20" | 35.61" | −0.9% | Compare |
| 315/75R17 | 17" | 35.60" | −0.9% | Compare |
| 345/50R22 | 22" | 35.58" | −1.0% | Compare |
| 295/75R18 | 18" | 35.42" | −1.4% | Compare |
| 355/55R20 | 20" | 35.37" | −1.6% | Compare |
One size up or down
Compare 345/55R21 with another size
Questions
- How tall is a 345/55R21 tire?
- A 345/55R21 tire is 35.9 inches tall (913 mm), calculated from the size. It is 13.6 inches wide with 7.5 inches sidewalls. Real tires vary by a few tenths of an inch between brands and tread patterns.
- What does 345/55R21 mean?
- 345/55R21 means a tire 345 mm wide, with sidewalls 55% as tall as the tire is wide (190 mm), radial construction (R), for a 21 inch wheel.
- How many revolutions per mile does a 345/55R21 tire make?
- About 561 revolutions per mile, based on a circumference of 112.9 inches. Under load the tire flattens slightly, so the maker's published figure is usually a little higher.
- What rim width fits a 345/55R21 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 335/55R21 instead of 345/55R21?
- 335/55R21 is −0.43 inches (−1.2%) in overall diameter, so at an indicated 60 mph you would be doing 59.3 mph. Differences under 3% are usually fine, but check clearance, load index and your vehicle's placard.