Comparison
245/45 R19 vs 285/30 R20
Switching from 245/45 R19 to 285/30 R20 is a plus-1 upgrade that wraps a shorter sidewall around a larger 20-inch wheel. This swap moves rolling diameter well outside the usual OEM tolerance. Indicated speed will drift far enough that recalibration is worth considering. Expect a more planted steering feel, at the cost of some of the cushioning a taller sidewall provides. The 3–5% diameter gap puts this in caution territory: doable on many cars, but verify clearance and consider recalibration.
TakeCommon upgrade for sportier handling and a tighter wheel-gap look on the same vehicle.
Quick math: 285/30 R20 is 24.1 mm shorter than 245/45 R19, shifting the speedometer by -3.43%.
Current Tire
New Tire
Ground line · scaled comparison
Slight Difference
Within ±5% — usable, recalibration recommended
Diameter change
-24.1 mm
-3.43%
Speedometer at 100
96.6 km/h
-3.43% error
Ground clearance
-12.0 mm
ride height delta
Sidewall change
-24.8 mm
revs/km: 468.8
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/compare/245-45-r19-vs-285-30-r20Detailed comparison
| Metric | 245/45 R19 | 285/30 R20 | Difference |
|---|---|---|---|
| Overall diameter | 703.1 mm | 679.0 mm | -24.1 mm (-3.43%) |
| Sidewall height | 110.3 mm | 85.5 mm | -24.8 mm |
| Circumference | 2.209 m | 2.133 m | -75.7 mm |
| Revs / km | 452.7 | 468.8 | +16.1 |
| Ground clearance | reference | -12.0 mm | -12.0 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 96.6 km/h | -3.43 km/h |
Verdict: warning
Between 3% and 5% — noticeable speedometer drift; recalibration may be advisable.
Speedometer impact
At a true 100 km/h, your dashboard will read 96.6 km/h after switching to 285/30 R20 — a -3.43% offset. Use the speedometer error calculator to recheck for other indicated speeds, and the speedometer error guide for the full background.
Ground clearance change
The new tire's half-diameter changes ride height by -12.0 mm. Small differences are absorbed by suspension travel, but anything beyond ±10 mm can affect headlight aim, fender clearance and bump-stop margin. See the plus-sizing guide before committing.
Back to
245/45 R19
Back to
285/30 R20
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