265/65 R18

What size is 265/65 R18?

265/65 R18 has an overall diameter of about 31.56 in, a section width of 10.43 in and a sidewall height of 6.78 in. It turns roughly 639 times per mile. Below are the exact figures plus in-tolerance plus/minus sizes you can switch to safely.

Fitment verdict

265/70 R17 stays within the configured tolerance for 265/65 R18: +0.1% diameter and +0.1% speedometer effect.

Metric This size: 265/65 R18 Alternative: 265/70 R17 Difference Verdict
Overall diameter 31.56 in 31.61 in +0.1% Within tolerance
Section width 10.43 in 10.43 in 0.00 in Computed difference
Sidewall height 6.78 in 7.30 in +0.52 in Computed difference
Circumference 99.16 in 99.29 in +0.1% Within tolerance
Speedo 0.0% +0.1% +0.1% 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 diameter31.56 in
Section width10.43 in
Sidewall height6.78 in
Circumference99.16 in
Revolutions 397 /km · 639 /mi

In-tolerance sizes

Alternative sizes that stay within the safe diameter tolerance:

Size Diameter Speedo Verdict
265/70 R17 +0.1% +0.1% ✓ OK
305/40 R22 +0.1% +0.1% ✓ OK
285/60 R18 -0.3% -0.3% ✓ OK
275/45 R22 +0.6% +0.6% ✓ OK
285/50 R20 -1.1% -1.1% ✓ OK
275/55 R20 +1.1% +1.1% ✓ OK
275/65 R18 +1.6% +1.6% ✓ OK
285/45 R22 +1.7% +1.7% ✓ OK
31x10.50 R15 -1.8% -1.8% ✓ OK
31x10.50 R16 -1.8% -1.8% ✓ OK
285/40 R22 -1.9% -1.9% ✓ OK
275/55 R19 -2.1% -2.1% ✓ OK

Compare sizes

Looks valid
Looks valid
Units
✓ Within toleranceDiameter +0.1% (+0.04 in) · US (~3%)
  • Within tolerance · Diameter +0.1%.
  • Speedo @ 60: 60 mph60.1 mph.
  • Sidewall +0.52 in · Width +0.00 in.
Diameter+0.1%+0.04 in
Speedo @ 60+0.1%60 mph60.1 mph
Sidewall+0.52 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
31.56 in 31.61 in+0.04 in
Sidewall
6.78 in 7.30 in+0.52 in
Width
10.43 in 10.43 in+0.00 in
Circumference
99.16 in 99.29 in+0.1%
Revs / mile
639 638
Speedo @ 60
60 mph 60.1 mph+0.1%
Δ⌀ +1.1 mm
  • Current265/65 R18
  • New265/70 R17
  • Grounded to the road: the axle rises +0.02 in.

Result report

265/65 R18 265/70 R17 · Within tolerance

Use this size when shopping: 265/70 R17

Use this size when shopping

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

Safe alternative sizes

SizeDiameterSpeedo @ 100Use this
−1″ 285/65R17+0.1%+0.1%
OE 265/65R18+0.0%+0.0%
+1″ 355/45R19+0.0%+0.0%
+2″ 245/60R20+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.