Examples
Examples
Try the starting example
- Original nominal rim width (inches)
- 8
- Original offset (mm), positive mounting face outward of center
- 40
- New nominal rim width (inches)
- 9
- New offset (mm)
- 35
- Measured original inner clearance (mm)
- 20
- Measured original outer clearance (mm)
- 25
- Nominal inboard edge movement, positive inward (mm)
- 7.7
- Nominal outboard edge movement, positive outward (mm)
- 17.7
- Original inner clearance minus inboard movement (mm)
- 12.3
- Original outer clearance minus outboard movement (mm)
- 7.3
Try another scenario
- Original nominal rim width (inches)
- 8
- Original offset (mm), positive mounting face outward of center
- 40
- New nominal rim width (inches)
- 9
- New offset (mm)
- 45
- Measured original inner clearance (mm)
- 20
- Measured original outer clearance (mm)
- 25
- Nominal inboard edge movement, positive inward (mm)
- 17.7
- Nominal outboard edge movement, positive outward (mm)
- 7.7
- Original inner clearance minus inboard movement (mm)
- 2.3
- Original outer clearance minus outboard movement (mm)
- 17.3
Calculation method
Calculation method
Nominal inboard edge movement, positive inward (mm)
Half-width change×25.4+offset change; exact decimal linear arithmetic.
Nominal outboard edge movement, positive outward (mm)
Half-width change×25.4−offset change.
Original inner clearance minus inboard movement (mm)
Entered original inner clearance−inward movement, preserving negative overlap.
Original outer clearance minus outboard movement (mm)
Entered original outer clearance−outward movement, preserving negative overlap.
Symbols and units
- a
- Original nominal rim width (inches)
- b
- Original offset (mm), positive mounting face outward of center
- c
- New nominal rim width (inches)
- d
- New offset (mm)
- e
- Measured original inner clearance (mm)
- f
- Measured original outer clearance (mm)
Use the units shown. A list keeps the order in which you enter its values. The symbol ^ means “raised to the power of”.
Assumptions & limits
Assumptions & limits
- A symmetric nominal rim-edge change model assuming unchanged lip geometry, hub and alignment. It is not backspacing-to-outer-lip measurement, tire growth, brake clearance or fitment authorization.
Are these inputs private?
These calculations run in your browser. A shared link contains the values you choose to share. Only questions submitted to the separate AI finder are sent to OpenAI.
Further reading
OpenStax: ratios, unit rates and supplied measurement arithmetic ↗
Background reading; this does not imply endorsement or independent review of SumFizz.