TireFitLab

255/40 R19 vs 275/40 R20

255/40 R19 vs 275/40 R20

275/40 R20 is outside the configured tolerance for 255/40 R19: +6.0% diameter and +6.0% speedometer effect.

Fitment verdict

275/40 R20 is outside the configured tolerance for 255/40 R19: +6.0% diameter and +6.0% speedometer effect.

Metric This size: 255/40 R19 Alternative: 275/40 R20 Difference Verdict
Overall diameter 27.03 in 28.66 in +6.0% Too tall
Section width 10.04 in 10.83 in +0.79 in Computed difference
Sidewall height 4.02 in 4.33 in +0.31 in Computed difference
Circumference 84.92 in 90.04 in +6.0% Too tall
Speedo 0.0% +6.0% +6.0% Outside tolerance

Compare sizes

Looks valid
Looks valid
Units
✕ Out of toleranceDiameter +6.0% (+1.63 in) · US (~3%)
  • Out of tolerance · Diameter +6.0%.
  • Speedo @ 60: 60 mph → 63.6 mph.
  • Sidewall +0.31 in · Width +0.79 in.
Diameter+6.0%+1.63 in
Speedo @ 60+6.0%60 mph → 63.6 mph
Sidewall+0.31 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.

Methodology
Diameter
27.03 in 28.66 in+1.63 in
Sidewall
4.02 in 4.33 in+0.31 in
Width
10.04 in 10.83 in+0.79 in
Circumference
84.92 in 90.04 in+6.0%
Revs / mile
746 704
Speedo @ 60
60 mph 63.6 mph+6.0%
Δ⌀ +41.4 mm
  • Current — 255/40 R19
  • New — 275/40 R20
  • Grounded to the road: the axle rises +0.81 in.

Result report

255/40 R19 275/40 R20 · Out of tolerance

Use this size when shopping: 275/40 R20

Use this size when shopping

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

Safe alternative sizes

SizeDiameterSpeedo @ 100Use this
−1″ 255/45R18+0.0%+0.0%
OE 255/40R19+0.0%+0.0%
+1″ 255/35R20-0.0%-0.0%
+2″ 255/30R21-0.0%-0.0%

255/40 R19 · 275/40 R20 · Methodology

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