195/65 R15 vs 225/40 R18

225/40 R18 stays within the configured tolerance for 195/65 R15: +0.4% diameter and +0.4% speedometer effect.

Fitment verdict

225/40 R18 stays within the configured tolerance for 195/65 R15: +0.4% diameter and +0.4% speedometer effect.

Metric	This size: 195/65 R15	Alternative: 225/40 R18	Difference	Verdict
Overall diameter	24.98 in	25.09 in	+0.4%	Within tolerance
Section width	7.68 in	8.86 in	+1.18 in	Computed difference
Sidewall height	4.99 in	3.54 in	-1.45 in	Computed difference
Circumference	78.48 in	78.81 in	+0.4%	Within tolerance
Speedo	0.0%	+0.4%	+0.4%	Within tolerance

Current tireLooks valid

New tireLooks valid

Market

Units

✓ Within toleranceDiameter +0.4% (+0.11 in) · US (~3%)

Diameter+0.4%+0.11 in

Speedo @ 60+0.4%60 mph → 60.3 mph

Sidewall-1.45 inWidth +1.18 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.

195/65 R15 225/40 R18 · Within tolerance

Use this size when shopping: 225/40 R18

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

Size	Diameter	Speedo @ 100
−1″ `215/65R14`	+0.1%	+0.1%
OE `195/65R15`	+0.0%	+0.0%
+1″ `285/40R16`	-0.0%	-0.0%
+2″ `135/75R17`	-0.0%	-0.0%

What changed

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