According to the Michelin website the 14.5R20 XL goes a mile in 420 revolutions.
So 5280 feet (1 mile)/482 =10.95 feet per revolution. In 4th gear and the transfer in high gear you get a overall reduction ratio of 1.1*1*6.722=7.3942. With the engine optimum rpm at 2700 rpm the wheel would be turning at 2700/7.3942=365.15 rpm. 365.15*10.95=3999.98 feet per minute. 3999.98*60 minutes=239,999.00 feet per hour 239,999/5280=45.45 mph
The Michelin XL 14.5R20 has a max speed rating of 56 mph.
Hope this helps,
Rick
---------- Original Message ----------------------------------
From: DDoyle9570@aol.com
Date: Thu, 27 Dec 2001 22:20:14 EST
>In a message dated 12/27/01 9:58:08 PM Central Daylight Time,
>jemery@execpc.com writes:
>
><< Isn't there an overdrive? Else you'd have to have a 5000 rpm engine to get
> anywhere with a top gear of 1.1:1
> >>
>Well, this is an interesting question. No, there is no overdrive.
>Interestingly, the 1.1 to 1 ratio is exactly the same gear ratio the original
>gas powered 5 speed manual has in high gear. The old gasser would do 62 MPH,
>but of course the Reo OA-331 gas engine would turn up to 3400 rpm.
>The Cat in the A3 only turns to 2700 rpm, however, the outside diameter of
>the Michelin 14.5R20XL tires is likely to be greater than the old 1100x20 or
>900x20 tires, which will affect the final drive ratio.
>As an aside, the Multifuel engine of the A2 turns to 2600 RPM, with the fifth
>gear (overdrive) ratio of .79 to one.
>If not helpful, hope you at least find this entertaining!
>David
>
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