33x12.50 R15 vs 275/70 R18

275/70 R18 stays within the configured tolerance for 33x12.50 R15: +0.5% diameter and +0.5% speedometer effect.

Geometric comparison

275/70 R18 stays within the configured tolerance for 33x12.50 R15: +0.5% diameter and +0.5% speedometer effect.

Geometric comparison
Metric	This size: 33x12.50 R15	Alternative: 275/70 R18	Difference	Verdict
Overall diameter	33.00 in	33.16 in	+0.5%	Within tolerance
Section width	12.50 in	10.83 in	-1.67 in	Computed difference
Sidewall height	9.00 in	7.58 in	-1.42 in	Computed difference
Circumference	103.67 in	104.17 in	+0.5%	Within tolerance
Speedo	0.0%	+0.5%	+0.5%	Within tolerance

Compare sizes

Current tireLooks valid

New tireLooks valid

Market

Units

High fitment riskWithin tolerance · Diameter +0.5% (+0.16 in) · US (~3%)

High fitment risk · This rating covers tire geometry only, not vehicle compatibility.
Diameter +0.5% · Ride-height change +0.08 in.
Speedometer reads low · 60 mph → 60.3 mph.
Sidewall -1.42 in · Width -1.67 in.

Diameter+0.5%+0.16 in

Speedo @ 60+0.5%60 mph → 60.3 mph

Sidewall-1.42 inWidth -1.67 in

Ride-height change+0.08 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: 33.00 in 33.16 in+0.16 in
Sidewall: 9.00 in 7.58 in-1.42 in
Width: 12.50 in 10.83 in-1.67 in
Circumference: 103.67 in 104.17 in+0.5%
Revs / mile: 611 608
Speedo @ 60: 60 mph 60.3 mph+0.5%
Ride-height change: 0.00 in +0.08 in
True distance per 100 indicated: 100 mi 100.5 mi+0.5%

Current — 33x12.50 R15
New — 275/70 R18
Grounded to the road: the axle rises +0.08 in.

Result report

33x12.50 R15 275/70 R18 · High fitment risk · Within tolerance

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Markdown link

[33x12.50 R15 vs 275/70 R18 Tire size comparison](https://tirefitlab.com/tire-size-calculator/?from=33x12.50+R15&to=275%2F70+R18&market=us)

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

In-tolerance alternative sizes

In-tolerance alternative sizes
Size	Diameter	Speedo @ 100
−1″ `345/70R14`	+0.0%	+0.0%
OE `305/75R15`	+0.0%	+0.0%
+1″ `335/65R16`	+0.4%	+0.4%

33x12.50 R15 · 275/70 R18 · Methodology

Technical check: 2026-06-28

What changed

Checked generated routes, metadata, sitemap inclusion and localized page rendering.

Methodology