245/35 R20 vs 255/40 R19

245/35 R20 vs 255/40 R19

255/40 R19 stays within the configured tolerance for 245/35 R20: +1.0% diameter and +1.0% speedometer effect.

Fitment verdict

255/40 R19 stays within the configured tolerance for 245/35 R20: +1.0% diameter and +1.0% speedometer effect.

Metric This size: 245/35 R20 Alternative: 255/40 R19 Difference Verdict
Overall diameter 26.75 in 27.03 in +1.0% Within tolerance
Section width 9.65 in 10.04 in +0.39 in Computed difference
Sidewall height 3.38 in 4.02 in +0.64 in Computed difference
Circumference 84.04 in 84.92 in +1.0% Within tolerance
Speedo 0.0% +1.0% +1.0% Within tolerance

Compare sizes

Looks valid
Looks valid
Units
✓ Within toleranceDiameter +1.0% (+0.28 in) · US (~3%)
  • Within tolerance · Diameter +1.0%.
  • Speedo @ 60: 60 mph60.6 mph.
  • Sidewall +0.64 in · Width +0.39 in.
Diameter+1.0%+0.28 in
Speedo @ 60+1.0%60 mph60.6 mph
Sidewall+0.64 inWidth +0.39 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
26.75 in 27.03 in+0.28 in
Sidewall
3.38 in 4.02 in+0.64 in
Width
9.65 in 10.04 in+0.39 in
Circumference
84.04 in 84.92 in+1.0%
Revs / mile
754 746
Speedo @ 60
60 mph 60.6 mph+1.0%
Δ⌀ +7.1 mm
  • Current245/35 R20
  • New255/40 R19
  • Grounded to the road: the axle rises +0.14 in.

Result report

245/35 R20 255/40 R19 · Within tolerance

Use this size when shopping: 255/40 R19

Use this size when shopping

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

Safe alternative sizes

SizeDiameterSpeedo @ 100Use this
−1″ 245/40R19-0.1%-0.1%
OE 245/35R20+0.0%+0.0%
+1″ 245/30R21+0.1%+0.1%
+2″ 135/45R22+0.1%+0.1%

245/35 R20 · 255/40 R19 · Methodology

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