Comparison
215/55 R16 vs 245/40 R18
Plus-sizing from 215/55 R16 to 245/40 R18 keeps overall diameter close to factory while opening room for a larger 18-inch wheel. This wheel and tire pairing trims or stretches rolling diameter by a small margin. Expect a slight but noticeable shift in indicated speed compared to the original tires. Less sidewall flex usually translates to crisper turn-in and a slightly stiffer ride over rough pavement. Diameter change stays inside the conservative ±3% safety window — an OEM-safe fitment on most vehicles.
TakeCommon upgrade for sportier handling and a tighter wheel-gap look on the same vehicle.
Quick math: 245/40 R18 is 10.3 mm taller than 215/55 R16, shifting the speedometer by +1.60%.
Current Tire
New Tire
Ground line · scaled comparison
Excellent Fit
Within ±3% — safe for daily driving
Diameter change
+10.3 mm
1.60%
Speedometer at 100
101.6 km/h
+1.60% error
Ground clearance
+5.2 mm
ride height delta
Sidewall change
-20.3 mm
revs/km: 487.3
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/compare/215-55-r16-vs-245-40-r18Detailed comparison
| Metric | 215/55 R16 | 245/40 R18 | Difference |
|---|---|---|---|
| Overall diameter | 642.9 mm | 653.2 mm | +10.3 mm (+1.60%) |
| Sidewall height | 118.3 mm | 98.0 mm | -20.3 mm |
| Circumference | 2.020 m | 2.052 m | +32.4 mm |
| Revs / km | 495.1 | 487.3 | -7.8 |
| Ground clearance | reference | +5.2 mm | +5.2 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 101.6 km/h | +1.60 km/h |
Verdict: excellent
Within ±3% — speedometer, ABS and traction control should behave normally.
Speedometer impact
At a true 100 km/h, your dashboard will read 101.6 km/h after switching to 245/40 R18 — a +1.60% 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 +5.2 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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215/55 R16
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245/40 R18
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