66 newyorker speedometer is off by 15 mph

[Zeusee]

Hi can someone tell me how many teeth the speedo gear in the transmission is suppose to have I think the one in my car is the wrong one helpppppppp thx

 

[1966newport]

tire size and rear gear ratio?

 

[commando1]

And now you know..

https://www.google.com/search?q=mop...ei2wWcw4HQBg&ved=0CAkQ_AUoAQ&biw=1224&bih=740