Comparison
215/45 R18 vs 245/45 R18
On the same 18-inch wheel, 245/45 R18 grows the section width by 30 mm versus 215/45 R18. This swap swings rolling diameter far enough to feel on the road. More tread on the ground tends to improve dry grip and stance, with a small fuel-economy and clearance tradeoff.
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.
TakeUseful when extra dry grip and stance matter more than a small fuel-economy hit.
Quick math: 245/45 R18 is 27.0 mm taller than 215/45 R18, shifting the speedometer by +4.15%.
Current Tire
New Tire
Ground line · scaled comparison
Slight Difference
Within ±5% — usable, recalibration recommended
Diameter change
+27.0 mm
4.15%
Speedometer at 100
104.1 km/h
+4.15% error
Ground clearance
+13.5 mm
ride height delta
Sidewall change
+13.5 mm
revs/km: 469.7
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/compare/215-45-r18-vs-245-45-r18Detailed comparison
| Metric | 215/45 R18 | 245/45 R18 | Difference |
|---|---|---|---|
| Overall diameter | 650.7 mm | 677.7 mm | +27.0 mm (+4.15%) |
| Sidewall height | 96.8 mm | 110.3 mm | +13.5 mm |
| Circumference | 2.044 m | 2.129 m | +84.8 mm |
| Revs / km | 489.2 | 469.7 | -19.5 |
| Ground clearance | reference | +13.5 mm | +13.5 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 104.1 km/h | +4.15 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 104.1 km/h after switching to 245/45 R18 — a +4.15% 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 +13.5 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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215/45 R18
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245/45 R18
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