Procal 3 power pack and tire revolutions

[Chomorro]

I flashed my power pack 2 today and saw you could change tire size. I looked up my tires and realized my tires are different diameters........

I have 275/40/20 on the rear which is 704 revs. And 255/40/20 which is 720 I believe.

Without buying new tires what should the procal be set at? I think the default is 771 or something.

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[sjmurphy34]

It should be based on your rear wheel size. If you're running 275/40/20 in the rear it should be set to 704.

 

[Chomorro]

It should be based on your rear wheel size. If you're running 275/40/20 in the rear it should be set to 704.

I actually went out there to change it and the lowest setting is 730 LOL which neither of my wheels are.

 

[Chomorro]

Just in case anyone else gets stuck on this setting. I called ford performance and they said they only care about the rear tire revolutions not the front.

That said, I told him my rear revs were 704 according to online and not on the scale. He used a ford calculator and said it's actually 727 and using the lowest 730 setting is close enough.

Just an FYI for anyone else out there.

 

[sjmurphy34]

Seems you are right. I found this in the procal3 instructions:

Another way to calculate revolutions per mile is by utilizing the sizing information written on the side of the tire. For a tire of the size P285/35-19, calculate tire revolutions per mile as follows: Revs per mile = 20850 / { [ (2 * 285 * 35) / 2540] + 19 } = 776.4 which rounds down to 776.

When you plug in 275/40/20 you do get 727. Not sure why it's different than all the websites use though.

 

[Chomorro]

Seems you are right. I found this in the procal3 instructions:


When you plug in 275/40/20 you do get 727. Not sure why it's different than all the websites use though.

Yeah I assumed the online calculators used the same formula but i guess not. At least i know to use the manual calculation if i change my wheels.

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