225/40 R18 vs 215/50 R17

215/50 R17 stays within the configured tolerance for 225/40 R18: +1.5% diameter and +1.5% speedometer effect.

Fitment verdict

215/50 R17 stays within the configured tolerance for 225/40 R18: +1.5% diameter and +1.5% speedometer effect.

Metric	This size: 225/40 R18	Alternative: 215/50 R17	Difference	Verdict
Overall diameter	25.09 in	25.46 in	+1.5%	Within tolerance
Section width	8.86 in	8.46 in	-0.39 in	Computed difference
Sidewall height	3.54 in	4.23 in	+0.69 in	Computed difference
Circumference	78.81 in	80.00 in	+1.5%	Within tolerance
Speedo	0.0%	+1.5%	+1.5%	Within tolerance

Current tireLooks valid

New tireLooks valid

Market

Units

✓ Within toleranceDiameter +1.5% (+0.38 in) · US (~3%)

Diameter+1.5%+0.38 in

Speedo @ 60+1.5%60 mph → 60.9 mph

Sidewall+0.69 inWidth -0.39 in

How this result is calculated

Computed from nominal tire-size geometry: diameter, circumference and speedometer error. It does not check wheel-arch, suspension or brake clearance.

225/40 R18 215/50 R17 · Within tolerance

Use this size when shopping: 215/50 R17

Geometric estimate. Always verify physical clearance (arches, suspension, brakes) before fitting.

Size	Diameter	Speedo @ 100
−1″ `205/50R17`	-0.1%	-0.1%
OE `225/40R18`	+0.0%	+0.0%
+1″ `155/50R19`	+0.1%	+0.1%
+2″ `215/30R20`	-0.0%	-0.0%

What changed

Reviewed deterministic geometry, load/speed references, sitemap inclusion and localized page shell.