Who can do the math?

[Lee Thompson]

With a 30 tooth speedo gear @ 90 mph reading--change to a 29 tooth gear @ 90 mph. What will my mph actually be? 92-94?

 

[chevyII]

I know local GM dealers/parts departments has a book with conversions for the gears.

 

[Lee Thompson]

?

Thanks----should have been "change to 31 tooth gear"