Changing tire size
Start with the tire calculator to compare diameter, sidewall, gearing effect, and indicated-versus-actual speed.
Fitment workshop
Wheel & Tire Fitment Tools
Compare tire sizes, protect AWD drivetrains, and measure wheel poke and inner clearance before spending money on a setup.
Decision guide
Start with the job you need to do
Buying different wheels
Use the offset calculator for inner clearance and fender poke, then verify bolt pattern and center bore.
Running staggered AWD tires
Compare front and rear rolling circumference. Use the vehicle manufacturer’s tolerance—not a universal internet rule—as the final authority.
Calculators & references
Tools in this category
Tire Size & Speedometer Correction
Compare sizes, visualize diameter changes, calculate speedometer error, and check staggered AWD compatibility.
Most popularWheel Offset Calculator
See exactly how a width and offset change moves a wheel toward the fender and suspension.
FitmentBolt Pattern & Hub Bore Checker
Check PCD and center-bore compatibility before buying wheels, including hub-ring sizing.
FitmentPlan fitment as a system, not one measurement
Wheel and tire fitment has three separate checks: tire diameter, physical wheel position, and mounting compatibility. A setup can pass one and fail another. Similar tire diameter does not guarantee fender clearance, and the right wheel offset does not make the wrong bolt pattern safe.
Start with the tire size comparison because rolling diameter affects speedometer accuracy, effective gearing, ABS behavior, and the relationship between front and rear axle speeds. Then compare wheel width and offset to see how the barrel and face move relative to the suspension and fender. Finish with bolt pattern and hub bore so the wheel can actually mount and center correctly.
The calculated dimensions are nominal. Actual tire section width and diameter vary with the approved rim width, inflation pressure, load, tread design, and manufacturer tolerances. Always compare the result with measured clearance on the vehicle and the specifications supplied by the tire, wheel, and vehicle manufacturers.
Methodology and responsibility
Formulas, assumptions, and limitations are shown on the individual tool pages. TunerBench is maintained as an educational planning resource. Verify safety-critical specifications with the vehicle or component manufacturer and the professional responsible for the work.
Reviewed August 11, 2026 · How TunerBench verifies calculations · Report an issue
Common questions
What should I check before ordering wheels?
Verify bolt pattern, center bore, wheel diameter and width, offset, brake clearance, tire load rating, and measured inner and outer clearance.
Is the ±1% AWD rule universal?
No. It is a useful warning threshold, not a manufacturer specification. Some systems have tighter tread-depth or circumference requirements, so consult the owner or service manual.
Why can two tires with the same marked size measure differently?
The sidewall size is nominal. Construction, tread, measuring rim, inflation, and load all affect the mounted dimensions.
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