255/35 R21
What size is 255/35 R21?
255/35 R21 has an overall diameter of about 28.03 in, a section width of 10.04 in and a sidewall height of 3.51 in. It turns roughly 720 times per mile. Below are the exact figures plus plus/minus sizes that stay within the selected diameter tolerance.
- Overall diameter: 28.03 in.
- Section width: 10.04 in.
- Sidewall height: 3.51 in.
- Revolutions: 447 /km · 720 /mi.
- In-tolerance sizes: 235/65 R16 (+0.0%).
Geometric comparison
235/65 R16 stays within the configured tolerance for 255/35 R21: 0.0% diameter and 0.0% speedometer effect.
| Metric | This size: 255/35 R21 | Alternative: 235/65 R16 | Difference | Verdict |
|---|---|---|---|---|
| Overall diameter | 28.03 in | 28.03 in | 0.0% | Within tolerance |
| Section width | 10.04 in | 9.25 in | -0.79 in | Computed difference |
| Sidewall height | 3.51 in | 6.01 in | +2.50 in | Computed difference |
| Circumference | 88.05 in | 88.05 in | 0.0% | Within tolerance |
| Speedo | 0.0% | 0.0% | 0.0% | Within tolerance |
Seasonal check
Winter tire rules coming up?
Check tread depth, markings and local winter requirements before the first cold spell instead of waiting for the appointment rush.
What this geometry means
255/35 R21 has a low-profile proportion. The marking combines nominal section width 10.04 in, sidewall ratio 35% and rim diameter 21 inches. One sidewall is 3.51 in; both sidewalls make up 25% of the 28.03 in overall diameter, while the rim makes up 75%.
The closest diameter entry is 235/65 R16 at +0.0%. Relative to 255/35 R21, it changes nominal section width by -0.79 in, each sidewall by +2.50 in and radius by +0.00 in.
At the nominal 88.05 in circumference, 1,000 rotations cover 2.24 km (1.39 mi); the inverse rates are 447/km and 720/mi.
Width endpoints in that set are 215/65 R17 (-1.57 in) and 275/40 R19 (+0.79 in) relative to 255/35 R21.
Curated alternatives: 12 sizes, spanning -1.8% to +1.7% in nominal diameter versus 255/35 R21.
Section-width mix versus 255/35 R21: 10 narrower, 1 equal-width and 1 wider entries.
This is a nominal geometry comparison only. Vehicle clearance, wheel width and offset, load and speed ratings, and manufacturer approval still require separate checks.
Specification
| Overall diameter | 28.03 in |
|---|---|
| Section width | 10.04 in |
| Sidewall height | 3.51 in |
| Circumference | 88.05 in |
| Revolutions | 447 /km · 720 /mi |
In-tolerance sizes
Alternative sizes that stay within the selected diameter tolerance:
| Size | Diameter | Speedo | Verdict |
|---|---|---|---|
| 235/65 R16 | +0.0% | +0.0% | ✓ OK |
| 255/45 R19 | +0.0% | +0.0% | ✓ OK |
| 215/65 R17 | -0.1% | -0.1% | ✓ OK |
| 235/60 R17 | +0.3% | +0.3% | ✓ OK |
| 235/55 R18 | +0.5% | +0.5% | ✓ OK |
| 235/50 R19 | +0.8% | +0.8% | ✓ OK |
| 225/55 R18 | -1.0% | -1.0% | ✓ OK |
| 245/45 R19 | -1.2% | -1.2% | ✓ OK |
| 275/40 R19 | -1.3% | -1.3% | ✓ OK |
| 225/60 R17 | -1.4% | -1.4% | ✓ OK |
| 225/65 R17 | +1.7% | +1.7% | ✓ OK |
| 225/65 R16 | -1.8% | -1.8% | ✓ OK |
Compare sizes
Editorial preset
These are TireFitLab editorial diameter-screening presets. Regional names choose a preset, not a national legal limit, ETRTO rule or vehicle approval. The AWD preset does not establish an allowable drivetrain mismatch. Use the exact vehicle and tyre manufacturer instructions; nominal geometry alone cannot approve fitment.
- Not recommended · This rating covers tire geometry only, not vehicle compatibility.
- Diameter +0.0% · Ride-height change +0.00 in.
- Speedometer unchanged · 60 mph → 60.0 mph.
- Sidewall +2.50 in · Width -0.79 in.
How this result is calculated
Computed from nominal tire-size geometry: diameter, circumference and speedometer error. It does not check vehicle placard approval, load/speed rating, rim-width range, wheel-arch, suspension or brake clearance.
MethodologyBefore fitting
- Check the vehicle placard and owner’s manual first.
- Match or exceed the required load index and speed rating.
- Confirm rim-width range, bolt pattern, hub bore, offset and fasteners.
- Inspect wheel-arch, suspension and brake clearance under real vehicle load.
- Check TPMS, cold pressure and local roadworthiness rules.
- Diameter
- 28.03 in 28.03 in+0.00 in
- Sidewall
- 3.51 in 6.01 in+2.50 in
- Width
- 10.04 in 9.25 in-0.79 in
- Circumference
- 88.05 in 88.05 in+0.0%
- Revs / mile
- 720 720
- Speedo @ 60
- 60 mph 60.0 mph+0.0%
- Ride-height change
- 0.00 in +0.00 in
- True distance per 100 indicated
- 100 mi 100.0 mi+0.0%
- Current —
255/35 R21 - New —
235/65 R16 - Grounded to the road: the axle rises +0.00 in.
Tires and wheels in one comparison
Result report
255/35 R21 235/65 R16 · Not recommended · Within tolerance
Copy/print uses this page state only; TireFitLab does not create an account or store a server-side report.
Geometric estimate. Always verify physical clearance (arches, suspension, brakes) before fitting.
In-tolerance alternative sizes
| Size | Diameter | Speedo @ 100 | Use this |
|---|---|---|---|
−1″ 245/40R20 | -1.1% | -1.1% | |
OE 255/35R21 | +0.0% | +0.0% | |
+1″ 265/30R22 | +0.8% | +0.8% | |
+2″ 265/25R23 | +0.7% | +0.7% |
More tools
- How to read a tire size
- Plus sizing guide
- Speedometer change from tire size: calculation and limits
- Speedometer error calculator
- 255mm Section width guide
- /35 Aspect ratio guide
- Rim diameter 21"
- Load index chart
- Speed rating chart
- Rim width and tire fitment guide
- Wheel offset guide
- Wheel spacers guide
- Tire pressure for heavy loads and towing