285/50 R20 vs 265/70 R17

285/50 R20 vs 265/70 R17

265/70 R17 stays within the configured tolerance for 285/50 R20: +1.2% diameter and +1.2% speedometer effect.

Fitment verdict

265/70 R17 stays within the configured tolerance for 285/50 R20: +1.2% diameter and +1.2% speedometer effect.

Metric This size: 285/50 R20 Alternative: 265/70 R17 Difference Verdict
Overall diameter 31.22 in 31.61 in +1.2% Within tolerance
Section width 11.22 in 10.43 in -0.79 in Computed difference
Sidewall height 5.61 in 7.30 in +1.69 in Computed difference
Circumference 98.08 in 99.29 in +1.2% Within tolerance
Speedo 0.0% +1.2% +1.2% Within tolerance

Compare sizes

Looks valid
Looks valid
Units
✓ Within toleranceDiameter +1.2% (+0.39 in) · US (~3%)
  • Within tolerance · Diameter +1.2%.
  • Speedo @ 60: 60 mph60.7 mph.
  • Sidewall +1.69 in · Width -0.79 in.
Diameter+1.2%+0.39 in
Speedo @ 60+1.2%60 mph60.7 mph
Sidewall+1.69 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
31.22 in 31.61 in+0.39 in
Sidewall
5.61 in 7.30 in+1.69 in
Width
11.22 in 10.43 in-0.79 in
Circumference
98.08 in 99.29 in+1.2%
Revs / mile
646 638
Speedo @ 60
60 mph 60.7 mph+1.2%
Δ⌀ +9.8 mm
  • Current285/50 R20
  • New265/70 R17
  • Grounded to the road: the axle rises +0.19 in.

Result report

285/50 R20 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″ 345/45R19+0.0%+0.0%
OE 285/50R20+0.0%+0.0%
+1″ 325/40R21+0.1%+0.1%
+2″ 195/60R22-0.0%-0.0%

285/50 R20 · 265/70 R17 · Methodology

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