275/55R20 vs 275/65R20: full comparison
| Measurement | 275/55R20 | 275/65R20 | Difference |
|---|---|---|---|
| Diameter | 31.91 in | 34.07 in | +2.17 in+6.8% |
| Section width | 10.83 in | 10.83 in | 0.00 in0.0% |
| Sidewall height | 5.95 in | 7.04 in | +1.08 in+18.2% |
| Circumference | 100.25 in | 107.05 in | +6.80 in+6.8% |
| Revs per mile | 632 | 592 | −40−6.4% |
Speedometer: indicated vs actual speed
With 275/65R20 fitted where 275/55R20 was the stock/calibrated size:
| Speedometer shows | Actual speed | Difference |
|---|---|---|
| 20 mph | 21.4 mph | +1.4 mph |
| 30 mph | 32.0 mph | +2.0 mph |
| 40 mph | 42.7 mph | +2.7 mph |
| 50 mph | 53.4 mph | +3.4 mph |
| 55 mph | 58.7 mph | +3.7 mph |
| 60 mph | 64.1 mph | +4.1 mph |
| 65 mph | 69.4 mph | +4.4 mph |
| 70 mph | 74.8 mph | +4.8 mph |
| 75 mph | 80.1 mph | +5.1 mph |
| 80 mph | 85.4 mph | +5.4 mph |
Recalculate for a gear ratio change too →
Will 275/65R20 fit where 275/55R20 was?
At +6.8%, 275/65R20 is enough larger than 275/55R20 that it commonly needs some accommodation -- trimming plastic liners/fender edges, a spacer, or a leveling kit on trucks/SUVs going bigger. Check clearance at full steering lock and full suspension compression before buying.
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- Speedometer calculator: true speed after a tire or gear ratio change.
Frequently asked questions
How much bigger is 275/65R20 than 275/55R20?
275/65R20 is 2.17 in taller in overall diameter (+6.8%) and 0.00 in the same width as in section width (0.0%) than 275/55R20.
Will 275/65R20 fit in place of 275/55R20?
At +6.8%, 275/65R20 is enough larger than 275/55R20 that it commonly needs some accommodation -- trimming plastic liners/fender edges, a spacer, or a leveling kit on trucks/SUVs going bigger. Check clearance at full steering lock and full suspension compression before buying.
Does swapping to 275/65R20 affect my speedometer?
With 275/65R20 fitted where 275/55R20 was calibrated, an indicated 60 mph is really about 64.1 mph. Beyond the ±3% guideline, plan to recalibrate the speedometer/odometer (with a programmer or at the dealer) for an accurate reading.
Does 275/65R20 change the ride height?
Yes -- half the diameter difference shows up at the axle, so 275/65R20 changes ride height by about 1.08 in higher compared with 275/55R20.
Do 275/55R20 and 275/65R20 use the same wheel (rim) diameter?
Yes -- both fit a 20 inch wheel, so only the tire itself changes, not the wheel.