Rev/Mi

[landtoy80]

What is the rev/mi on a stock 80?
When I had the dash apart on the Supra, it was marked on the speedo what the rev/mi is. When I had the dash apart on the 80 I don't remember seeing it. Is it there?

I have the replacement gear that made my 285 Wild Country RVT correct via GPS.
My 2285 Xterrains are off just a bit.
What is the rev/mi with the replaced speedo gear in it?

 

[landtoy80]

Per Michelin web site the factory tire size of P275/70R16 is Overall Diameter 31.3"
Tire Revolutions per Mile =666 at 45mph
So stock must be 666 rev/mi.

So how do you do the math to tell the rev/mi with the replacement gear?