275/40 R20 vs 245/45 R20

245/45 R20 stays within the configured tolerance for 275/40 R20: +0.1% diameter and +0.1% speedometer effect.

Geometric comparison

245/45 R20 stays within the configured tolerance for 275/40 R20: +0.1% diameter and +0.1% speedometer effect.

Geometric comparison
Metric	This size: 275/40 R20	Alternative: 245/45 R20	Difference	Verdict
Overall diameter	28.66 in	28.68 in	+0.1%	Within tolerance
Section width	10.83 in	9.65 in	-1.18 in	Computed difference
Sidewall height	4.33 in	4.34 in	+0.01 in	Computed difference
Circumference	90.04 in	90.10 in	+0.1%	Within tolerance
Speedo	0.0%	+0.1%	+0.1%	Within tolerance

Compare sizes

Current tireLooks valid

New tireLooks valid

Market

Units

Requires verificationWithin tolerance · Diameter +0.1% (+0.02 in) · US (~3%)

Requires verification · This rating covers tire geometry only, not vehicle compatibility.
Diameter +0.1% · Ride-height change +0.01 in.
Speedometer reads low · 60 mph → 60.0 mph.
Sidewall +0.01 in · Width -1.18 in.

Diameter+0.1%+0.02 in

Speedo @ 60+0.1%60 mph → 60.0 mph

Sidewall+0.01 inWidth -1.18 in

Ride-height change+0.01 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: 28.66 in 28.68 in+0.02 in
Sidewall: 4.33 in 4.34 in+0.01 in
Width: 10.83 in 9.65 in-1.18 in
Circumference: 90.04 in 90.10 in+0.1%
Revs / mile: 704 703
Speedo @ 60: 60 mph 60.0 mph+0.1%
Ride-height change: 0.00 in +0.01 in
True distance per 100 indicated: 100 mi 100.1 mi+0.1%

Current — 275/40 R20
New — 245/45 R20
Grounded to the road: the axle rises +0.01 in.

Result report

275/40 R20 245/45 R20 · Requires verification · Within tolerance

Plan budget for this size: 245/45 R20

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Plan budget for this size

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Markdown link

[275/40 R20 vs 245/45 R20 Tire size comparison](https://tirefitlab.com/tire-size-calculator/?from=275%2F40+R20&to=245%2F45+R20&market=us)

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Budget$150–$210Per tire Mid-range$195–$280Per tire Premium$280–$395Per tire

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

In-tolerance alternative sizes

In-tolerance alternative sizes
Size	Diameter	Speedo @ 100	Use this
OE `275/40R20`	+0.0%	+0.0%

275/40 R20 · 245/45 R20 · Methodology

Technical check: 2026-06-28

What changed

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

Methodology