Tire size calculator
Type two tire sizes to compare their diameter, width, sidewall, circumference and revolutions per mile, what your speedometer reads after the change, and how much ground clearance moves at the axle. Metric (265/70R17) and flotation (33x12.50R17) sizes both work.
The 285/70R17 is 32.71 in tall: 1.10 in (3.5%) taller than the 265/70R17 at 31.61 in. At an indicated 60 mph you'd be doing 62.1 mph.
| InchesMillimeters | 265/ | 285/ | Change |
|---|---|---|---|
| Diameter | 31.61802.8 | 32.71830.8 | +1.10 +3.5%+28.0 +3.5% |
| Width | 10.43265 | 11.22285 | +0.79 +20 |
| Sidewall | 7.30185.5 | 7.85199.5 | +0.55 +14.0 |
| Circumference | 99.32522 | 102.82610 | +3.5 +88 |
| Revs per mileRevs per km | 638396 | 617383 | -21 -13 |
Each figure is rounded separately, so related figures can differ in the last digit.
These are size-code figures only. Whether a size fits, clears and carries your load depends on your vehicle and the tire, so check with a tire shop.
Only the section width changes, from 10.43 in to 11.22 in. The aspect ratio is a percentage of the width, so each sidewall grows with it, by 0.55 in, and the 285/70R17 ends up 1.10 in taller overall.
Flotation sizes state their height and width in inches, and those numbers are nominal: makers aim at them, and real tires of the same size measure a little differently.
A speedometer that read true on the 265/70R17 reads low on the 285/70R17: an indicated 60 mph is a true 62.1 mph.
| Speedometer shows | True speed on the 285/70R17 | Error |
|---|---|---|
| 30 mph | 31.0 mph | +1.0 |
| 45 mph | 46.6 mph | +1.6 |
| 60 mph | 62.1 mph | +2.1 |
| 70 mph | 72.4 mph | +2.4 |
| 80 mph | 82.8 mph | +2.8 |
| Speedometer shows | True speed on the 285/70R17 | Error |
|---|---|---|
| 50 km/h | 51.7 km/h | +1.7 |
| 80 km/h | 82.8 km/h | +2.8 |
| 100 km/h | 103.5 km/h | +3.5 |
| 110 km/h | 113.8 km/h | +3.8 |
| 120 km/h | 124.2 km/h | +4.2 |
The odometer records about 9,660 miles for every 10,000 you drive.
Ground clearance at the axle rises by 0.55 in: half the diameter change, unloaded. By calculated diameter the 265/70R17 is a 32-inch tire and the 285/70R17 a 33-inch tire.
Full page: 265/70R17 vs 285/70R17
Searched comparisons
- 275/55R20 vs 275/60R20
- 265/70R17 vs 285/70R17
- 265/70R17 vs 275/70R17
- 265/70R17 vs 285/75R17
- 265/70R17 vs 265/75R17
- 255/75R17 vs 265/70R17
- 245/75R17 vs 265/70R17
- 285/70R17 vs 285/75R17
- 285/70R17 vs 315/70R17
- 285/70R17 vs 33x12.50R17
- 315/70R17 vs 35x12.50R17
- 265/75R16 vs 285/75R16
- 235/85R16 vs 265/75R16
- 285/75R16 vs 305/70R16
- 235/75R15 vs 31x10.50R15
- 275/65R18 vs 285/65R18
- 265/60R18 vs 275/65R18
- 275/70R18 vs 285/65R18
- 305/70R18 vs 35x12.50R18
- 275/55R20 vs 285/55R20
- 275/60R20 vs 285/60R20
- 275/60R20 vs 295/60R20
- 275/65R20 vs 35x12.50R20
- 265/50R20 vs 275/55R20
Tire sizes in inches
- 285/70R17 in inches
- 275/70R18 in inches
- 285/75R16 in inches
- 285/75R17 in inches
- 295/70R18 in inches
- 33x12.50R17 in metric
- 35x12.50R20 in metric
Inch sizes in metric
- 31 inch tire in metric
- 32 inch tire in metric
- 33 inch tire in metric
- 34 inch tire in metric
- 35 inch tire in metric
Guides
- Speedometer error after a tire size change
- Plus sizing: a bigger wheel at the same overall diameter
- Tire size comparison chart
Sources
- BFGoodrich: How to read a tire sidewall, retrieved 29 October 2026
- NIST Guide to the SI (SP 811), Appendix B.8: Factors for units listed alphabetically, retrieved 29 October 2026
- Performance Plus Tire: What is a 285/70R17 equivalent to?, retrieved 29 October 2026
- Performance Plus Tire: 285/70R17 instead of 265/70R17 (6 Oct 2026), retrieved 29 October 2026
- Performance Plus Tire: What is a 33x12.50R17 equivalent to? (26 Jun 2026), retrieved 29 October 2026
- SimpleTire: 285/70R17 tire size, retrieved 29 October 2026
- tiresize.com: 285-70R17 size page, retrieved 29 October 2026
- Toyo Tires: tire finder by size, retrieved 29 October 2026
Data verified 29 October 2026 against these sources. See the methodology for how disagreements are resolved.