Comparison
225/45 R18 vs 235/45 R17
Switching from 225/45 R18 to 235/45 R17 steps down to a 17-inch wheel — a familiar move for winter and dedicated all-terrain sets. This sizing approach trims or stretches rolling diameter by a small margin. More tread on the ground tends to improve dry grip and stance, with a small fuel-economy and clearance tradeoff.
The speedometer offset is small but measurable; worth keeping in mind if you watch the dash closely. Overall the swap sits inside the safe ±3% diameter window, so ABS, traction control and gearing behave normally.
TakePractical direction for winter wheels, chains, or rougher pavement where cushioning matters.
Quick math: 235/45 R17 is 16.4 mm shorter than 225/45 R18, shifting the speedometer by -2.49%.
Current Tire
New Tire
Ground line · scaled comparison
Excellent Fit
Within ±3% — safe for daily driving
Diameter change
-16.4 mm
-2.49%
Speedometer at 100
97.5 km/h
-2.49% error
Ground clearance
-8.2 mm
ride height delta
Sidewall change
+4.5 mm
revs/km: 494.8
Permalink for this comparison:
/compare/225-45-r18-vs-235-45-r17Detailed comparison
| Metric | 225/45 R18 | 235/45 R17 | Difference |
|---|---|---|---|
| Overall diameter | 659.7 mm | 643.3 mm | -16.4 mm (-2.49%) |
| Sidewall height | 101.3 mm | 105.8 mm | +4.5 mm |
| Circumference | 2.073 m | 2.021 m | -51.5 mm |
| Revs / km | 482.5 | 494.8 | +12.3 |
| Ground clearance | reference | -8.2 mm | -8.2 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 97.5 km/h | -2.49 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 97.5 km/h after switching to 235/45 R17 — a -2.49% 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 -8.2 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.
Back to
225/45 R18
Back to
235/45 R17
Drivers also compare
Closely-related fitments and plus-size swaps for 225/45 R18 and 235/45 R17.
225/45 R18 vs 255/40 R18
Wider variation on the same rim — more grip, less clearance.
Δ 0.23%
215/50 R17 vs 235/45 R17
Wider variation on the same rim — more grip, less clearance.
Δ 0.54%
225/45 R18 vs 245/40 R18
Wider variation on the same rim — more grip, less clearance.
Δ 0.99%
205/50 R17 vs 235/45 R17
Wider variation on the same rim — more grip, less clearance.
Δ 1.02%
235/45 R17 vs 255/40 R17
Wider variation on the same rim — more grip, less clearance.
Δ 1.17%
225/45 R18 vs 235/45 R18
Wider variation on the same rim — more grip, less clearance.
Δ 1.36%
215/45 R18 vs 225/45 R18
Wider variation on the same rim — more grip, less clearance.
Δ 1.38%
235/45 R17 vs 245/45 R17
Wider variation on the same rim — more grip, less clearance.
Δ 1.40%
Related topics