TireFitLab

235/65 R16

What size is 235/65 R16?

235/65 R16 has an overall diameter of about 28.03 in, a section width of 9.25 in and a sidewall height of 6.01 in. It turns roughly 720 times per mile. Below are the exact figures plus plus/minus sizes that stay within the selected diameter tolerance.

Geometric comparison

255/35 R21 stays within the configured tolerance for 235/65 R16: 0.0% diameter and 0.0% speedometer effect.

Geometric comparison
Metric This size: 235/65 R16 Alternative: 255/35 R21 Difference Verdict
Overall diameter 28.03 in 28.03 in 0.0% Within tolerance
Section width 9.25 in 10.04 in +0.79 in Computed difference
Sidewall height 6.01 in 3.51 in -2.50 in Computed difference
Circumference 88.05 in 88.05 in 0.0% Within tolerance
Speedo 0.0% 0.0% 0.0% Within tolerance

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What this geometry means

235/65 R16 has a taller-sidewall proportion. The marking combines nominal section width 9.25 in, sidewall ratio 65% and rim diameter 16 inches. One sidewall is 6.01 in; both sidewalls make up 43% of the 28.03 in overall diameter, while the rim makes up 57%.

Curated alternatives: 12 sizes, spanning -1.8% to +1.7% in nominal diameter versus 235/65 R16.

Width endpoints in that set are 215/65 R17 (-0.79 in) and 275/40 R19 (+1.57 in) relative to 235/65 R16.

At the nominal 88.05 in circumference, 1,000 rotations cover 2.24 km (1.39 mi); the inverse rates are 447/km and 720/mi.

The closest diameter entry is 255/35 R21 at +0.0%. Relative to 235/65 R16, it changes nominal section width by +0.79 in, each sidewall by -2.50 in and radius by +0.00 in.

Section-width mix versus 235/65 R16: 5 narrower, 3 equal-width and 4 wider entries.

This is a nominal geometry comparison only. Vehicle clearance, wheel width and offset, load and speed ratings, and manufacturer approval still require separate checks.

Specification

Specification
Overall diameter 28.03 in
Section width 9.25 in
Sidewall height 6.01 in
Circumference 88.05 in
Revolutions 447 /km · 720 /mi

In-tolerance sizes

Alternative sizes that stay within the selected diameter tolerance:

In-tolerance sizes
Size Diameter Speedo Verdict
255/35 R21 +0.0% +0.0% ✓ OK
255/45 R19 +0.0% +0.0% ✓ OK
215/65 R17 -0.1% -0.1% ✓ OK
235/60 R17 +0.3% +0.3% ✓ OK
235/55 R18 +0.5% +0.5% ✓ OK
235/50 R19 +0.8% +0.8% ✓ OK
225/55 R18 -1.0% -1.0% ✓ OK
245/45 R19 -1.2% -1.2% ✓ OK
275/40 R19 -1.3% -1.3% ✓ OK
225/60 R17 -1.4% -1.4% ✓ OK
225/65 R17 +1.7% +1.7% ✓ OK
225/65 R16 -1.8% -1.8% ✓ OK

Compare sizes

Looks valid
Looks valid
Units
Not recommendedWithin tolerance · Diameter +0.0% (+0.00 in) · US (~3%)
  • Not recommended · This rating covers tire geometry only, not vehicle compatibility.
  • Diameter +0.0% · Ride-height change +0.00 in.
  • Speedometer unchanged · 60 mph → 60.0 mph.
  • Sidewall -2.50 in · Width +0.79 in.
Diameter+0.0%+0.00 in
Speedo @ 60+0.0%60 mph → 60.0 mph
Sidewall-2.50 inWidth +0.79 in
Ride-height change+0.00 inDiameter ÷ 2
How this result is calculated

Computed from nominal tire-size geometry: diameter, circumference and speedometer error. It does not check vehicle placard approval, load/speed rating, rim-width range, wheel-arch, suspension or brake clearance.

Methodology

Before fitting

  • Check the vehicle placard and owner’s manual first.
  • Match or exceed the required load index and speed rating.
  • Confirm rim-width range, bolt pattern, hub bore, offset and fasteners.
  • Inspect wheel-arch, suspension and brake clearance under real vehicle load.
  • Check TPMS, cold pressure and local roadworthiness rules.
Diameter
28.03 in 28.03 in+0.00 in
Sidewall
6.01 in 3.51 in-2.50 in
Width
9.25 in 10.04 in+0.79 in
Circumference
88.05 in 88.05 in+0.0%
Revs / mile
720 720
Speedo @ 60
60 mph 60.0 mph+0.0%
Ride-height change
0.00 in +0.00 in
True distance per 100 indicated
100 mi 100.0 mi+0.0%
Δ⌀ +0.00 inΔ↔ +0.79 in
  • Current — 235/65 R16
  • New — 255/35 R21
  • Grounded to the road: the axle rises +0.00 in.

Result report

235/65 R16 255/35 R21 · Not recommended · Within tolerance

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

In-tolerance alternative sizes

In-tolerance alternative sizes
SizeDiameterSpeedo @ 100Use this
−1″ 255/65R15+0.1%+0.1%
OE 235/65R16+0.0%+0.0%

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Last reviewed: 2026-07-22

Technical check
2026-07-22
Content updated
2026-07-22
What changed
  • Added a localized engine-derived geometry signature and matching Markdown narrative.
Methodology