Calculators
Plan your build with confidence. Every tool updates instantly as you type.
Offset & backspacing calculator
Convert between wheel width, offset (mm), and backspacing (in).
Backspacing
5.50"
Backspacing = (Width / 2) + (Offset / 25.4) + 0.5
Tire size comparison
Compare two tire sizes side by side — diameter, sidewall, circumference, revs/mile, and speedometer error.
Original tire
New tire
Diameter
—
Sidewall
—
Circumference
—
Revs / mile
—
Speedo error
—
Ø = (width × aspect / 1270) + rim_diameter
Metric to imperial tire converter
Convert a metric tire size (e.g. 285/70R17) to the imperial / flotation equivalent (e.g. 32.7×11.2R17).
Overall diameter
—
Section width
—
Imperial size
—
Ø = (width × aspect / 1270) + rim_diameter
Wheel & tire clearance comparison
Compare two wheel/tire setups to see how far each tire sits inward (backspacing) and outward (poke) from the hub.
Current setup
New setup
Inner edge Δ
—
inward vs current
Outer edge Δ (poke)
—
outward vs current
Tire width Δ
—
Lift needed for tire Δ
—
Backspacing = (wheel_width / 2) + (offset / 25.4) + 0.5
Bolt pattern converter
Convert imperial bolt circles to metric and vice versa.
Metric
—
Imperial
—
mm = inches × 25.4
Common: