What speedo gear for 3:23’s

I changed to 3:55 gears (new gears stamped 3:55 on them). I have P275-60-15 tires that measure 27 5/8".It is a 833 4 sp.
A chart on Ebay said 33 tooth so I ordered one, and the speedo is 10 MPH fast at 60 MPH.
I contacted the guy that sold it to me, and he said my tire size puts it closer to a 34 tooth.But that 1 tooth is equal to 2 MPH.
Does anybody know the sweet spot? I don't want to keep buying these at $20.00 to guess it.
Author: admin