225/45 R17 vs 255/35 R18

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.

Fitment verdict

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

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

Looks valid
Looks valid
Units
✓ Within toleranceDiameter +0.2% (+0.06 in) · US (~3%)
  • Within tolerance · Diameter +0.2%.
  • Speedo @ 60: 60 mph60.1 mph.
  • Sidewall -0.47 in · Width +1.18 in.
Diameter+0.2%+0.06 in
Speedo @ 60+0.2%60 mph60.1 mph
Sidewall-0.47 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.

Methodology
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%
Δ⌀ +1.4 mm
  • Current225/45 R17
  • New255/35 R18
  • Grounded to the road: the axle rises +0.03 in.

Result report

225/45 R17 255/35 R18 · Within tolerance

Use this size when shopping: 255/35 R18

Use this size when shopping

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

Safe alternative sizes

SizeDiameterSpeedo @ 100Use this
−1″ 285/40R16+0.0%+0.0%
OE 225/45R17+0.0%+0.0%
+1″ 295/30R18-0.0%-0.0%
+2″ 305/25R19+0.1%+0.1%

225/45 R17 · 255/35 R18 · Methodology

Last reviewed: 2026-06-28
What changed
  • Reviewed deterministic geometry, load/speed references, sitemap inclusion and localized page shell.