Comparison
245/35 R19 vs 245/45 R18
Switching from 245/35 R19 to 245/45 R18 steps down to a 18-inch wheel — a familiar move for winter and dedicated all-terrain sets. This setup noticeably changes overall diameter compared to OEM. The speedometer error is noticeable and may warrant a recalibration if you rely on indicated speed. More sidewall typically improves comfort and curb protection, especially on city streets. Diameter delta falls in the cautious 3–5% range, where speedometer recalibration and a careful clearance check are worth doing.
TakePractical direction for winter wheels, chains, or rougher pavement where cushioning matters.
Quick math: 245/45 R18 is 23.6 mm taller than 245/35 R19, shifting the speedometer by +3.61%.
Current Tire
New Tire
Ground line · scaled comparison
Slight Difference
Within ±5% — usable, recalibration recommended
Diameter change
+23.6 mm
3.61%
Speedometer at 100
103.6 km/h
+3.61% error
Ground clearance
+11.8 mm
ride height delta
Sidewall change
+24.5 mm
revs/km: 469.7
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/compare/245-35-r19-vs-245-45-r18Detailed comparison
| Metric | 245/35 R19 | 245/45 R18 | Difference |
|---|---|---|---|
| Overall diameter | 654.1 mm | 677.7 mm | +23.6 mm (+3.61%) |
| Sidewall height | 85.8 mm | 110.3 mm | +24.5 mm |
| Circumference | 2.055 m | 2.129 m | +74.1 mm |
| Revs / km | 486.6 | 469.7 | -16.9 |
| Ground clearance | reference | +11.8 mm | +11.8 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 103.6 km/h | +3.61 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 103.6 km/h after switching to 245/45 R18 — a +3.61% 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 +11.8 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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245/35 R19
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245/45 R18
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