33x12.50 R15 vs 33x12.50 R18

33x12.50 R18 stays within the configured tolerance for 33x12.50 R15: 0.0% diameter and 0.0% speedometer effect.

Geometric comparison

33x12.50 R18 stays within the configured tolerance for 33x12.50 R15: 0.0% diameter and 0.0% speedometer effect.

Geometric comparison
Metric	This size: 33x12.50 R15	Alternative: 33x12.50 R18	Difference	Verdict
Overall diameter	33.00 in	33.00 in	0.0%	Within tolerance
Section width	12.50 in	12.50 in	0.00 in	Computed difference
Sidewall height	9.00 in	7.50 in	-1.50 in	Computed difference
Circumference	103.67 in	103.67 in	0.0%	Within tolerance
Speedo	0.0%	0.0%	0.0%	Within tolerance

Compare sizes

Current tireLooks valid

New tireLooks valid

Market

Units

High fitment riskWithin tolerance · Diameter +0.0% (+0.00 in) · US (~3%)

High fitment risk · 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 -1.50 in · Width +0.00 in.

Diameter+0.0%+0.00 in

Speedo @ 60+0.0%60 mph → 60.0 mph

Sidewall-1.50 inWidth +0.00 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: 33.00 in 33.00 in+0.00 in
Sidewall: 9.00 in 7.50 in-1.50 in
Width: 12.50 in 12.50 in+0.00 in
Circumference: 103.67 in 103.67 in+0.0%
Revs / mile: 611 611
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%

Current — 33x12.50 R15
New — 33x12.50 R18
Grounded to the road: the axle rises +0.00 in.

Result report

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

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Markdown link

[33x12.50 R15 vs 33x12.50 R18 Tire size comparison](https://tirefitlab.com/tire-size-calculator/?from=33x12.50+R15&to=33x12.50+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 · 33x12.50 R18 · Methodology

Technical check: 2026-06-28

What changed

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

Methodology