Does anyone know how to convert degrees and minutes of toe on an alignment printout to fractional inches. I.e. 0 degrees 30 mins equals to x inches.

Thanks

 

The math is:

Angle = ASIN(toe/wheel diameter)
which is approximately =
angle in degrees = toe/wheel diameter * 180/pi

example for 15" wheels, and 1/16" toe per side

1/16" / 15" * 57 = 0.24* per side.

0.24* = 14 minutes

Every 1/32 of an inch of toe is 0.12 degrees or 7 minutes

 

That doesn't convert to fractions of an inch just to other measurment of angle.

 

Find the sine of the angle from the toe required per side/wheel (inches) divided by the diameter of the wheel rim (inches)
For example 1/16th inch total "toe-in" which is 1/32" per side = 0.03125"
Assuming a rim diameter of 15"
Toe angle per side is sine of 0.003125/15 = 0.002083 equivalent to 0.119366 degrees which is also 7.16 minutes.
Total toe-in is double the per side toe-in, in this case 14.32 minutes.

 

do you use the wheel diameter or the overall diameter of the tire?

 

I believe it is the wheel diameter.

 

Not sure if this chart would be any help.

http://www.smartracingproducts.com/p...conversion.pdf

 

Sorry, I noticed it after posted. That is why I removed and posted other information. I hope the other information is useful.

 

It's helpful but still don't if my alignment is correct: I asked dealer to align my car with stock 19" wheels to 1/16" toe out front and 3/16" toe in rear. Printout shows total front toe to be -0*10' and rear toe to be 0*31' . Trying to find out if they did what I asked.

 

1/16 (.0625) would be about 11 degrees and 3/16 (.1875) would be between 33-34 degrees. You got 10 and 31.

 

I ran into this the other day...

http://www.ground-control-store.com/toe-out.htm

 

Referencing toe by minutes (fraction of a degree: 60 min = 1.0 degree) is the only correct way to do it as it is an angle measurement which is independent of rim or tire diameter.

The only reason people use fractions of an inch or mm is either out of convenience or laziness to compute the minute conversion. This can deliver very undesirable results. Depending on where you make your measurement on the wheels, the resultant toe angle will differ significantly. For example, if you request 3/16" rear toe, did you want that measured at the tire or the rim? What diameter rim, 18" or 19"? A quick calculation shows that 3/16" on the edge of 18" rims is 34.2 minutes, on 19" rims is 32.4 minutes, and on the outside of a 26.5" diameter tire is 24.6 minutes.

 

Point taken and I completely agree. Toe angle is best decribed in degrees or minutes of a degree as it is an angle after all. In all practicality though most people you ask about how much rear toe angle do you run on your GT3 at the track respond 3/16". I need to know is my setting of 31 minutes or 1/2 of a degree total toe in the rear close to this "3/16"" toe angle. Or should I have it reset before this upcoming track weekend. Incidently how much front toe out do you guys run at the track.

Thanks in advance