Quick Answer
- The difference between two tire sizes is the gap in overall diameter. 265/70R17 to 285/70R17 is 1.10 in (28 mm), +3.5% taller (calculated).
- That is also your speedometer error: an indicated 60 mph is 62.1 mph. Continental says to keep rolling circumference within 3% of the original.
- AWD and 4WD makers ask for the same size on all four wheels and publish no percentage. Ford and Jeep warn that major size differences can disable the system or damage the transfer case.
Enter Tire Specifications
① Original Tire
→ 265/70R17
② Compare Tire
→ 285/70R17
🔄
Enter tire specs above and click Calculate to compare
Supports P-metric (225/65R17) and Imperial/flotation (31x10.5R15) formats
Tire Size Difference Chart: 265 vs 285 and Other Swaps
Calculated from the size codes. Positive means the new tire is taller.
| Original | New | Difference in | Difference mm | Difference % | Revs per mile gap | True speed at 60 mph |
|---|---|---|---|---|---|---|
| 265/70R17 | 275/70R17 | +0.55 | +14 | +1.7% | 11 | 61.0 mph |
| 265/70R17 | 285/70R17 | +1.10 | +28 | +3.5% | 22 | 62.1 mph |
| 275/70R17 | 285/70R17 | +0.55 | +14 | +1.7% | 11 | 61.0 mph |
| 265/70R17 | 285/75R17 | +2.22 | +56 | +7.0% | 42 | 64.2 mph |
| 245/65R17 | 265/65R17 | +1.02 | +26 | +3.5% | 23 | 62.1 mph |
| 235/55R18 | 245/55R18 | +0.43 | +11 | +1.5% | 11 | 60.9 mph |
| 225/65R17 | 235/65R17 | +0.51 | +13 | +1.8% | 12 | 61.1 mph |
| 285/70R17 | 275/70R17 | -0.55 | -14 | -1.7% | -11 | 59.0 mph |
| 275/65R18 | 295/65R18 | +1.02 | +26 | +3.2% | 19 | 61.9 mph |
| 245/75R16 | 265/75R16 | +1.18 | +30 | +3.9% | 25 | 62.3 mph |
How Much One Width or Aspect Step Changes the Diameter
Moving up one standard step at the same rim, calculated. Width steps are on a 65 series 17 inch tire; aspect steps are on a 245 mm wide 17 inch tire.
| Width step | Diameter change | Percent |
|---|---|---|
| 185 to 195 | +0.51 in | +1.9% |
| 195 to 205 | +0.51 in | +1.9% |
| 205 to 215 | +0.51 in | +1.9% |
| 215 to 225 | +0.51 in | +1.8% |
| 225 to 235 | +0.51 in | +1.8% |
| 235 to 245 | +0.51 in | +1.8% |
| 245 to 255 | +0.51 in | +1.7% |
| 255 to 265 | +0.51 in | +1.7% |
| 265 to 275 | +0.51 in | +1.7% |
| 275 to 285 | +0.51 in | +1.6% |
| 285 to 295 | +0.51 in | +1.6% |
| Aspect step | Diameter change | Percent |
|---|---|---|
| 30 to 35 | +0.96 in | +4.2% |
| 35 to 40 | +0.96 in | +4.1% |
| 40 to 45 | +0.96 in | +3.9% |
| 45 to 50 | +0.96 in | +3.8% |
| 50 to 55 | +0.96 in | +3.6% |
| 55 to 60 | +0.96 in | +3.5% |
| 60 to 65 | +0.96 in | +3.4% |
| 65 to 70 | +0.96 in | +3.3% |
| 70 to 75 | +0.96 in | +3.2% |
What Tire and Vehicle Makers Say About Size Differences
| Source | Statement (paraphrased) |
|---|---|
| Continental Tire, plus-sizing guidance | Keep rolling circumference within 3% of the original. A larger deviation can affect speedometer accuracy, ABS and stability control. |
| Ford and Jeep owner's manuals | Ford says major size differences between axles can make the AWD system stop working or damage it. Jeep says proper operation depends on tires of equal size, type and circumference on each wheel. |
| Subaru, Honda and Toyota owner's manuals | Subaru asks for the same size, circumference, construction, brand and load range on all four tires. Honda says a different size or construction can make VSA, AWD and ABS work incorrectly. Toyota asks for the same brand and tread pattern on 4WD models. |
| USTMA | Acceptable load capacity or overall diameter does not imply acceptable vehicle clearance. Check clearance at all four wheel positions through full suspension travel and steering lock. |
More on drive systems in the AWD tire size guide; BMW owners can use the xDrive rolling diameter check, and winter sets are in the winter tire sizing guide. For front against rear pairs use the staggered fitment calculator and for a spare the spare tire compatibility calculator.
How to Find the Difference Between Two Tire Sizes
- 1Enter the original tire size and the size you are considering, in metric (265/70R17) or inch (33x12.50R15) format.
- 2Click Calculate and Compare.
- 3Read the diameter difference in inches, mm and percent on the Stats tab, and the true speeds on the Speedometer tab.
- 4Check the percentage against the 3% limit and your owner's manual, and look at the AWD guide if your vehicle drives all four wheels.