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Convert Toe Angle to Inches


Toe Angle for One Wheel in Degrees:  Use decimal degrees for < 1 degree

Tire Diameter: AP2 stock 17" tires are 24.6", Nitto NT01 255/45/17 tires have a diameter 24.7", See this link to estimate tire diameter: Tire Diameter Estimator

This calculator works with metric numbers if you enter the Tire Diameter in metric.


Formula: Toe-In_inches_per_wheel = (Tire_Diameter / 2) x sin(Toe_Angle) x 2

Tire radius is one half of tire diameter, x 2 is to account for leading & trailing edge of tire

Toe for one wheel in inches =

Total Toe in inches =   Assumes same toe on both wheels


See this link to Convert Toe Inches to Degrees
 
The Honda AP1 S2000 Shop Manual calls for 0.25 inch of total toe-in at the rear wheels. Toe-in in inches is the difference between measurements A and B in the diagram below. Shop Manual toe-in in inches is measured on the tire tread at the axle level.

0.25 Inch (0.58) of Total Toe-In

Measurement A - B = 0.25" or 1/4" total toe-in. Note 0.0625" = 1/16"
 
The Shop Manual 0.25 inch of total toe-in is made up of:
 
    0.0625" measured at leading tread of the left tire + 0.0625" measured at trailing tread of the left tire +
        0.0625" measured at leading tread of the right tire + 0.0625" measured at trailing tread of the right tire. 0.0625" x 4 = 0.25".
 
When measuring toe in degrees you do not need to double the measurement for the leading and trailing edge of the tires as you do when using inches. If one rear wheel measures 0.29 of toe-in and the other measures 0.29, then total rear toe-in is 0.58, not 1.16.
 
AP1: 0.25 inch (1/4" or 6mm) of total rear toe-in is equal to 0.58 (decimal degrees) of total toe-in.
 
AP2: 0.14 inch (3.7mm) of total rear toe-in is equal to 0.33 (decimal degrees) of total toe-in.
 
If you use string to measure toe and use the wheel rim for measurements your numbers will not match up with the Shop Manual because Shop Manual toe is measured at the tire tread. You can get pretty close by decreasing the tire tread measurement by 25% to approximate the correct rim measurement.
 
If someone says they run 1/4 inch of toe-in you need to ask:
 
    Is that total toe-in? (total for both wheels on the axle, or just a single wheel?)
    Where was the 1/4" measured, at the rim or tire tread? (tire tread is the norm)
    Was the 1/4" measured on one side of the tire, or both sides (leading & trailing tread on both tires = normal total toe)

For more info on aligning the S2000 see the Alignment and Corner Balance pages.

By Rob Robinette

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