Comparison
245/45 R18 vs 285/35 R20
Going from 245/45 R18 to 285/35 R20 steps up to a 20-inch rim while trimming sidewall to stay near OEM rolling diameter. This wheel and tire pairing swings rolling diameter far enough to feel on the road. Expect a more planted steering feel, at the cost of some of the cushioning a taller sidewall provides.
Indicated speed will drift far enough that recalibration is worth considering. Diameter delta falls in the cautious 3–5% range, where speedometer recalibration and a careful clearance check are worth doing.
TakeCommon upgrade for sportier handling and a tighter wheel-gap look on the same vehicle.
Quick math: 285/35 R20 is 29.8 mm taller than 245/45 R18, shifting the speedometer by +4.40%.
Current Tire
New Tire
Ground line · scaled comparison
Slight Difference
Within ±5% — usable, recalibration recommended
Diameter change
+29.8 mm
4.40%
Speedometer at 100
104.4 km/h
+4.40% error
Ground clearance
+14.9 mm
ride height delta
Sidewall change
-10.5 mm
revs/km: 449.9
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/compare/245-45-r18-vs-285-35-r20Detailed comparison
| Metric | 245/45 R18 | 285/35 R20 | Difference |
|---|---|---|---|
| Overall diameter | 677.7 mm | 707.5 mm | +29.8 mm (+4.40%) |
| Sidewall height | 110.3 mm | 99.8 mm | -10.5 mm |
| Circumference | 2.129 m | 2.223 m | +93.6 mm |
| Revs / km | 469.7 | 449.9 | -19.8 |
| Ground clearance | reference | +14.9 mm | +14.9 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 104.4 km/h | +4.40 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 104.4 km/h after switching to 285/35 R20 — a +4.40% 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 +14.9 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.
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245/45 R18
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285/35 R20
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