245/45 R18 vs 225/55 R17

225/55 R17 stays within the configured tolerance for 245/45 R18: +0.2% diameter and +0.2% speedometer effect.

Fitment verdict

225/55 R17 stays within the configured tolerance for 245/45 R18: +0.2% diameter and +0.2% speedometer effect.

Metric	This size: 245/45 R18	Alternative: 225/55 R17	Difference	Verdict
Overall diameter	26.68 in	26.74 in	+0.2%	Within tolerance
Section width	9.65 in	8.86 in	-0.79 in	Computed difference
Sidewall height	4.34 in	4.87 in	+0.53 in	Computed difference
Circumference	83.82 in	84.02 in	+0.2%	Within tolerance
Speedo	0.0%	+0.2%	+0.2%	Within tolerance

Current tireLooks valid

New tireLooks valid

Market

Units

✓ Within toleranceDiameter +0.2% (+0.06 in) · US (~3%)

Diameter+0.2%+0.06 in

Speedo @ 60+0.2%60 mph → 60.1 mph

Sidewall+0.53 inWidth -0.79 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.

245/45 R18 225/55 R17 · Within tolerance

Use this size when shopping: 225/55 R17

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

Size	Diameter	Speedo @ 100
−1″ `205/60R17`	+0.0%	+0.0%
OE `245/45R18`	+0.0%	+0.0%
+1″ `195/50R19`	-0.0%	-0.0%
+2″ `155/55R20`	+0.1%	+0.1%

What changed

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