225/45 R17 vs 255/35 R18

255/35 R18 stays within the configured tolerance for 225/45 R17: +0.2% diameter and +0.2% speedometer effect.

Geometric comparison

255/35 R18 stays within the configured tolerance for 225/45 R17: +0.2% diameter and +0.2% speedometer effect.

Geometric comparison
Metric	This size: 225/45 R17	Alternative: 255/35 R18	Difference	Verdict
Overall diameter	24.97 in	25.03 in	+0.2%	Within tolerance
Section width	8.86 in	10.04 in	+1.18 in	Computed difference
Sidewall height	3.99 in	3.51 in	-0.47 in	Computed difference
Circumference	78.45 in	78.63 in	+0.2%	Within tolerance
Speedo	0.0%	+0.2%	+0.2%	Within tolerance

Compare sizes

Current tireLooks valid

New tireLooks valid

Market

Units

Requires verificationWithin tolerance · Diameter +0.2% (+0.06 in) · US (~3%)

Requires verification · This rating covers tire geometry only, not vehicle compatibility.
Diameter +0.2% · Ride-height change +0.03 in.
Speedometer reads low · 60 mph → 60.1 mph.
Sidewall -0.47 in · Width +1.18 in.

Diameter+0.2%+0.06 in

Speedo @ 60+0.2%60 mph → 60.1 mph

Sidewall-0.47 inWidth +1.18 in

Ride-height change+0.03 inDiameter ÷ 2

How this result is calculated

Computed from nominal tire-size geometry: diameter, circumference and speedometer error. It does not check vehicle placard approval, load/speed rating, rim-width range, wheel-arch, suspension or brake clearance.

Methodology

Before fitting

Check the vehicle placard and owner’s manual first.
Match or exceed the required load index and speed rating.
Confirm rim-width range, bolt pattern, hub bore, offset and fasteners.
Inspect wheel-arch, suspension and brake clearance under real vehicle load.
Check TPMS, cold pressure and local roadworthiness rules.

Diameter: 24.97 in 25.03 in+0.06 in
Sidewall: 3.99 in 3.51 in-0.47 in
Width: 8.86 in 10.04 in+1.18 in
Circumference: 78.45 in 78.63 in+0.2%
Revs / mile: 808 806
Speedo @ 60: 60 mph 60.1 mph+0.2%
Ride-height change: 0.00 in +0.03 in
True distance per 100 indicated: 100 mi 100.2 mi+0.2%

Current — 225/45 R17
New — 255/35 R18
Grounded to the road: the axle rises +0.03 in.

Result report

225/45 R17 255/35 R18 · Requires verification · Within tolerance

Plan budget for this size: 255/35 R18

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Plan budget for this size

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Markdown link

[225/45 R17 vs 255/35 R18 Tire size comparison](https://tirefitlab.com/tire-size-calculator/?from=225%2F45+R17&to=255%2F35+R18&market=us)

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Budget$100–$140Per tire Mid-range$130–$185Per tire Premium$185–$260Per tire

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

In-tolerance alternative sizes

In-tolerance alternative sizes
Size	Diameter	Speedo @ 100	Use this
OE `225/45R17`	+0.0%	+0.0%

225/45 R17 · 255/35 R18 · Methodology

Technical check: 2026-06-28

What changed

Checked generated routes, metadata, sitemap inclusion and localized page rendering.

Methodology