Comparison
215/40 R18 vs 215/50 R16
Minus-sizing from 215/40 R18 to 215/50 R16 pairs a smaller 16-inch wheel with more rubber between the rim and road. This wheel and tire pairing preserves rolling diameter within a hair of the original. The taller sidewall adds cushioning over potholes and rougher roads, with a softer overall ride.
Speedometer drift stays small enough that most drivers won't notice it day to day. Overall the swap sits inside the safe ±3% diameter window, so ABS, traction control and gearing behave normally.
TakeTypical choice for a dedicated winter or off-road setup where extra sidewall pays off.
Quick math: 215/50 R16 is 7.8 mm shorter than 215/40 R18, shifting the speedometer by -1.24%.
Current Tire
New Tire
Ground line · scaled comparison
Excellent Fit
Within ±3% — safe for daily driving
Diameter change
-7.8 mm
-1.24%
Speedometer at 100
98.8 km/h
-1.24% error
Ground clearance
-3.9 mm
ride height delta
Sidewall change
+21.5 mm
revs/km: 512.2
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/compare/215-40-r18-vs-215-50-r16Detailed comparison
| Metric | 215/40 R18 | 215/50 R16 | Difference |
|---|---|---|---|
| Overall diameter | 629.2 mm | 621.4 mm | -7.8 mm (-1.24%) |
| Sidewall height | 86.0 mm | 107.5 mm | +21.5 mm |
| Circumference | 1.977 m | 1.952 m | -24.5 mm |
| Revs / km | 505.9 | 512.2 | +6.4 |
| Ground clearance | reference | -3.9 mm | -3.9 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 98.8 km/h | -1.24 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 98.8 km/h after switching to 215/50 R16 — a -1.24% 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 -3.9 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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215/40 R18
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215/50 R16
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