275/65R18 vs 285/65R18: full comparison
| Measurement | 275/65R18 | 285/65R18 | Difference |
|---|---|---|---|
| Diameter | 32.07 in | 32.59 in | +0.51 in+1.6% |
| Section width | 10.83 in | 11.22 in | +0.39 in+3.6% |
| Sidewall height | 7.04 in | 7.29 in | +0.26 in+3.6% |
| Circumference | 100.77 in | 102.37 in | +1.61 in+1.6% |
| Revs per mile | 629 | 619 | −10−1.6% |
Speedometer: indicated vs actual speed
With 285/65R18 fitted where 275/65R18 was the stock/calibrated size:
| Speedometer shows | Actual speed | Difference |
|---|---|---|
| 20 mph | 20.3 mph | +0.3 mph |
| 30 mph | 30.5 mph | +0.5 mph |
| 40 mph | 40.6 mph | +0.6 mph |
| 50 mph | 50.8 mph | +0.8 mph |
| 55 mph | 55.9 mph | +0.9 mph |
| 60 mph | 61.0 mph | +1.0 mph |
| 65 mph | 66.0 mph | +1.0 mph |
| 70 mph | 71.1 mph | +1.1 mph |
| 75 mph | 76.2 mph | +1.2 mph |
| 80 mph | 81.3 mph | +1.3 mph |
Recalculate for a gear ratio change too →
Will 285/65R18 fit where 275/65R18 was?
At +1.6%, 285/65R18 is within the ±3% most tire shops and manufacturers accept without recalibrating the speedometer or expecting rubbing -- it should generally bolt on, though wheel width, offset, and suspension travel still matter.
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Frequently asked questions
How much bigger is 285/65R18 than 275/65R18?
285/65R18 is 0.51 in taller in overall diameter (+1.6%) and 0.39 in wider in section width (+3.6%) than 275/65R18.
Will 285/65R18 fit in place of 275/65R18?
At +1.6%, 285/65R18 is within the ±3% most tire shops and manufacturers accept without recalibrating the speedometer or expecting rubbing -- it should generally bolt on, though wheel width, offset, and suspension travel still matter.
Does swapping to 285/65R18 affect my speedometer?
With 285/65R18 fitted where 275/65R18 was calibrated, an indicated 60 mph is really about 61.0 mph. That small a difference is within the ±3% most shops treat as close enough not to recalibrate.
Does 285/65R18 change the ride height?
Yes -- half the diameter difference shows up at the axle, so 285/65R18 changes ride height by about 0.26 in higher compared with 275/65R18.
Do 275/65R18 and 285/65R18 use the same wheel (rim) diameter?
Yes -- both fit a 18 inch wheel, so only the tire itself changes, not the wheel.