Speedo Gears Revisited

[Bill <Y1TopBanana73@xxxxxxxxx>]

Gary H posted this info quite a while ago. I'm trying to hunt down a
couple of speedo gears and I just want to make sure I'm doing this
right.

A 255/60/15 tire (27" tall) w/ a 3.23 ratio would require a 19 tooth gear?
A 255/60/15 tire (27" tall) w/ a 3.55 ratio would require a 21 tooth gear?

A 215/70/14 tire (25.85" tall) w/ a 2.93 ratio would require an 18 tooth gear?
A 215/70/14 tire (25.85" tall) w/ a 3.23 ratio would require an 20 tooth gear?

If I'm right, what's the best source for these gears these days?
Brewers? _______?

Thanks
-- 
Bill M
65 Coronet 500 'vert
http://1962to1965mopar.ornocar.com/mmo62008.html


---------- Forwarded message ----------
From: Gary H. <62to65mopar@xxxxxxxxxxx>
Date: Fri, May 18, 2007 at 11:11 PM
Subject: RE: Tire Size Conversion
To: 1962to1965mopars@xxxxxxxxxx

For your 1965 (or 1962s to 1965's)

A. Divide 63.36 by the car's tire circumference. The circumference is
tire diameter times 3.14. (e.g.,a 26 inch tall tire has 81.64
circumference so 63.36/81.64 = .776

B. Multiply that result by 8 (8 x .776 = 6.208)

C. Multiply that result by your axle ratio (e.g., 3.23 x 6.208 = 20.05)

The result is the number of teeth needed on your car's speedometer
pinion, or 20 in the example above.

Gary H.