Comparison
225/40 R18 vs 225/50 R16
225/50 R16 drops the rim from 18 to 16 inches versus 225/40 R18, trading wheel size for taller sidewall. This setup barely shifts the rolling circumference. Extra sidewall absorbs impacts more readily — a sensible bias for daily commuting and broken pavement.
The speedometer offset is mild and well inside what most cars can tolerate without recalibration. Diameter change stays inside the conservative ±3% safety window — an OEM-safe fitment on most vehicles.
TakeTypical choice for a dedicated winter or off-road setup where extra sidewall pays off.
Quick math: 225/50 R16 is 5.8 mm shorter than 225/40 R18, shifting the speedometer by -0.91%.
Current Tire
New Tire
Ground line · scaled comparison
Excellent Fit
Within ±3% — safe for daily driving
Diameter change
-5.8 mm
-0.91%
Speedometer at 100
99.1 km/h
-0.91% error
Ground clearance
-2.9 mm
ride height delta
Sidewall change
+22.5 mm
revs/km: 504.1
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/compare/225-40-r18-vs-225-50-r16Detailed comparison
| Metric | 225/40 R18 | 225/50 R16 | Difference |
|---|---|---|---|
| Overall diameter | 637.2 mm | 631.4 mm | -5.8 mm (-0.91%) |
| Sidewall height | 90.0 mm | 112.5 mm | +22.5 mm |
| Circumference | 2.002 m | 1.984 m | -18.2 mm |
| Revs / km | 499.5 | 504.1 | +4.6 |
| Ground clearance | reference | -2.9 mm | -2.9 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 99.1 km/h | -0.91 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 99.1 km/h after switching to 225/50 R16 — a -0.91% 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 -2.9 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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225/40 R18
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225/50 R16
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