Independent wheel & tire calculators

Know how it fits before you buy.

Compare tire size, wheel offset, backspacing, clearance, and speedometer impact in one modern workspace.

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4 focused tools 0 accounts required 100% browser-local
Live comparison preview 205/55R16 vs 225/45R17
Within 1%
16"
17"
Diameter change +0.38%
Ground clearance+1.2 mm
Outer position+2.7 mm
Speed at 60 mph60.2 mph

01InstantLive results as you type

02TransparentFormulas and assumptions shown

03PracticalCopy, print, and share

The calculator suite

One workspace. Every critical dimension.

Start with the complete fitment comparison or open a focused tool for a faster answer.

Complete comparison

Wheel & Tire Fitment

Compare current and proposed wheel-and-tire dimensions, rim position, ground-clearance change, and estimated speedometer impact.

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Wheel position

Wheel Offset & Backspacing

Convert offset and backspacing or compare how two wheel widths and offsets change nominal inner and outer position.

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Tire dimensions

Tire Size Comparison

Compare sidewall height, diameter, circumference, radius, and revolutions per mile or kilometre for two tire sizes.

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Speed impact

Speedometer Error

Estimate how a tire-diameter change affects actual speed at a selected indicated speed and across a reference table.

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Designed for real decisions

More useful than a single number.

Understand what changed, why it matters, and what still needs physical verification.

Calculated dimensional changes

Compare nominal sidewall height, overall diameter, circumference, and revolutions per mile from the dimensions you enter.

Wheel position from the mounting face

Compare how wheel width and offset change nominal inner and outer rim-edge position.

Speedometer impact estimate

Larger tires travel farther per revolution, causing the odometer and speedometer to read low.

Shareable results

Copy a direct link to any calculation result so you can share it with a shop or forum.

What these calculators cannot do

These are dimensional calculators. They cannot verify brake, suspension, fender, or body clearance; confirm hub bore fit; assess load or speed ratings; or recalibrate vehicle electronics. Always verify fitment physically and consult a qualified professional before purchasing.

Wheel and Tire Fitment Planning

Use these calculators to compare tire dimensions, wheel position, backspacing, ground-clearance changes, and estimated speedometer effects. Always verify physical clearance and manufacturer requirements before purchasing.