255/40 R19

What size is 255/40 R19?

255/40 R19 has an overall diameter of about 27.03 in, a section width of 10.04 in and a sidewall height of 4.02 in. It turns roughly 746 times per mile. Below are the exact figures plus in-tolerance plus/minus sizes you can switch to safely.

Fitment verdict

255/35 R20 stays within the configured tolerance for 255/40 R19: 0.0% diameter and 0.0% speedometer effect.

Metric This size: 255/40 R19 Alternative: 255/35 R20 Difference Verdict
Overall diameter 27.03 in 27.03 in 0.0% Within tolerance
Section width 10.04 in 10.04 in 0.00 in Computed difference
Sidewall height 4.02 in 3.51 in -0.50 in Computed difference
Circumference 84.92 in 84.91 in 0.0% Within tolerance
Speedo 0.0% 0.0% 0.0% Within tolerance

Seasonal check

Planning a long summer drive?

Use the budget and running-cost tools before a trip, especially if the current tyres are worn or the replacement size changes diameter.

Estimate tyre budget

Specification

Overall diameter27.03 in
Section width10.04 in
Sidewall height4.02 in
Circumference84.92 in
Revolutions 464 /km · 746 /mi

In-tolerance sizes

Alternative sizes that stay within the safe diameter tolerance:

Size Diameter Speedo Verdict
255/35 R20 -0.0% -0.0% ✓ OK
255/45 R18 +0.0% +0.0% ✓ OK
215/65 R16 -0.1% -0.1% ✓ OK
235/60 R16 +0.3% +0.3% ✓ OK
215/60 R17 +0.5% +0.5% ✓ OK
235/55 R17 +0.5% +0.5% ✓ OK
215/70 R15 -0.7% -0.7% ✓ OK
235/50 R18 +0.8% +0.8% ✓ OK
245/35 R20 -1.0% -1.0% ✓ OK
225/55 R17 -1.1% -1.1% ✓ OK
245/40 R19 -1.2% -1.2% ✓ OK
245/45 R18 -1.3% -1.3% ✓ OK

Compare sizes

Looks valid
Looks valid
Units
✓ Within toleranceDiameter -0.0% (-0.00 in) · US (~3%)
  • Within tolerance · Diameter -0.0%.
  • Speedo @ 60: 60 mph60.0 mph.
  • Sidewall -0.50 in · Width +0.00 in.
Diameter-0.0%-0.00 in
Speedo @ 60-0.0%60 mph60.0 mph
Sidewall-0.50 inWidth +0.00 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 27.03 in-0.00 in
Sidewall
4.02 in 3.51 in-0.50 in
Width
10.04 in 10.04 in+0.00 in
Circumference
84.92 in 84.91 in-0.0%
Revs / mile
746 746
Speedo @ 60
60 mph 60.0 mph-0.0%
Δ⌀ −0.1 mm
  • Current255/40 R19
  • New255/35 R20
  • Grounded to the road: the axle rises -0.00 in.

Result report

255/40 R19 255/35 R20 · Within tolerance

Use this size when shopping: 255/35 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%

More tools

Last reviewed: 2026-06-28

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