Brake Clearance Template Comparator
Compare brake caliper dimensions with a wheel maker's brake clearance template. Check radial and spoke clearance in mm and inches.
Compare wheel-specific clearance templates.
Brake Clearance Template Comparator: Tire Size Inputs
Compare two tire sizes here. Use the formulas and reference tables below for this tool's specific calculation.
How Brake Clearance Template Comparator Works?
The Brake Clearance Template Comparator works by comparing measured caliper dimensions with the clearance profile a wheel maker publishes for each wheel. The comparison has 4 steps.
Measure the caliper
Measure the caliper's outermost radius from hub center and its distance from the hub mounting face.
Enter the wheel template
Copy the wheel maker's template values for the same points.
Compare each point
The comparator subtracts each caliper value from the matching template value.
Apply a margin
The comparator flags any point with less than 3 mm (0.12 in) of clearance.
Brake Clearance Template Comparator Formula
The Brake Clearance Template Comparator formula is Clearance_i = Template_i − Caliper_i at each measuring point i, with a pass when Clearance_i ≥ margin.
C_i = T_i − K_iC_i ≥ m (typical m = 3 mm)C_min = min(C_i)- T_i
- Template limit at point i (mm)
- K_i
- Measured caliper dimension at point i (mm)
- m
- Safety margin (mm)
Worked example
A template allows 160 mm of radius at the spoke plane, and the caliper measures 158 mm there. The clearance is 2.0 mm (0.08 in), under a 3 mm margin, so the wheel needs a 3 mm spacer or a different design.
Brake Clearance Template Comparator Conversion Table
The Brake Clearance Template Comparator conversion table shows a sample 5-point check of a caliper against a wheel template.
| Measuring point | Caliper | Template limit | Clearance | Result |
|---|---|---|---|---|
| Caliper outer radius at mounting face | 152 mm (5.98 in) | 158 mm (6.22 in) | +6.0 mm | Pass |
| Caliper face to spoke distance | 18 mm (0.71 in) | 21 mm (0.83 in) | +3.0 mm | Pass |
| Caliper radius at spoke plane | 158 mm (6.22 in) | 160 mm (6.30 in) | +2.0 mm | Below 3 mm margin |
| Rotor diameter allowed | 355 mm (13.98 in) | 365 mm (14.37 in) | +10 mm | Pass |
| Minimum wheel diameter | 18 in | 19 in | +1 in | Pass |
Values are an illustrative example. Template points and limits differ by wheel maker and design.
What is Brake Clearance Template Comparator?
A Brake Clearance Template Comparator is a tool that checks a brake caliper's size against a wheel maker's published clearance profile. Wheel diameter alone does not decide caliper clearance. Spoke shape and barrel profile decide clearance.
Two 18-inch wheels with the same offset can differ by 10 mm (0.4 in) or more in caliper room. Big brake kit makers and wheel makers publish templates for that reason.
The comparator suits big brake kit installs, wheel swaps on performance cars and winter wheel choices.
What are the uses of Brake Clearance Template Comparator?
There are 4 main uses of the Brake Clearance Template Comparator, including big brake kit planning and winter wheel selection.
Big brake kit planning
Confirm wheels clear a 6-piston caliper.
Winter wheel selection
Find a smaller wheel that still clears stock brakes.
Spacer sizing
Find the spacer that restores spoke clearance.
Wheel design comparison
Compare 2 wheel designs of the same size.
Related Wheel Geometry & Fitment Tools
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Account for spacer thickness.