Comparison
215/45 R17 vs 255/40 R17
Stepping from 215/45 R17 to 255/40 R17 keeps the 17-inch wheel but widens the section by 40 mm. This setup trims or stretches rolling diameter by a small margin.
The speedometer offset is small but measurable; worth keeping in mind if you watch the dash closely. Expect a more planted steering feel, at the cost of some of the cushioning a taller sidewall provides. Extra width broadens the footprint for more grip, but check inner liner and strut clearance before fitting. Overall the swap sits inside the safe ±3% diameter window, so ABS, traction control and gearing behave normally.
TakeReasonable performance-leaning swap as long as fender and suspension clearance check out.
Quick math: 255/40 R17 is 10.5 mm taller than 215/45 R17, shifting the speedometer by +1.68%.
Current Tire
New Tire
Ground line · scaled comparison
Excellent Fit
Within ±3% — safe for daily driving
Diameter change
+10.5 mm
1.68%
Speedometer at 100
101.7 km/h
+1.68% error
Ground clearance
+5.3 mm
ride height delta
Sidewall change
+5.3 mm
revs/km: 500.6
Permalink for this comparison:
/compare/215-45-r17-vs-255-40-r17Detailed comparison
| Metric | 215/45 R17 | 255/40 R17 | Difference |
|---|---|---|---|
| Overall diameter | 625.3 mm | 635.8 mm | +10.5 mm (+1.68%) |
| Sidewall height | 96.8 mm | 102.0 mm | +5.3 mm |
| Circumference | 1.964 m | 1.997 m | +33.0 mm |
| Revs / km | 509.1 | 500.6 | -8.4 |
| Ground clearance | reference | +5.3 mm | +5.3 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 101.7 km/h | +1.68 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 101.7 km/h after switching to 255/40 R17 — a +1.68% 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 +5.3 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
215/45 R17
Back to
255/40 R17
Drivers also compare
Closely-related fitments and plus-size swaps for 215/45 R17 and 255/40 R17.
205/50 R17 vs 255/40 R17
Wider variation on the same rim — more grip, less clearance.
Δ 0.16%
225/45 R17 vs 255/40 R17
Wider variation on the same rim — more grip, less clearance.
Δ 0.24%
215/45 R17 vs 245/40 R17
Wider variation on the same rim — more grip, less clearance.
Δ 0.40%
235/45 R17 vs 255/40 R17
Wider variation on the same rim — more grip, less clearance.
Δ 1.17%
245/40 R17 vs 255/40 R17
Wider variation on the same rim — more grip, less clearance.
Δ 1.27%
215/45 R17 vs 225/45 R17
Wider variation on the same rim — more grip, less clearance.
Δ 1.44%
205/45 R17 vs 215/45 R17
Wider variation on the same rim — more grip, less clearance.
Δ 1.46%
215/50 R17 vs 255/40 R17
Wider variation on the same rim — more grip, less clearance.
Δ 1.70%
Related topics