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Re: Tyres for TR6

To: triumphs@Autox.Team.Net
Subject: Re: Tyres for TR6
From: Triumph_TR4@ridgecrest.ca.us (Darrell Leach)
Date: Wed, 13 May 1998 18:12:20 -0700
Posted-date: Wed, 13 May 1998 18:08:46 -0700 (PDT)
Lex Garey wrote:
>Good day -
>Regarding speedometer errors with various tire sizes,
>Triumph_TR4@ridgecrest.ca.us wrote :
>
>>The formula for this is:
>>(Original Tire Diameter/Replacement Tire Diameter) x Indicated Speed
>
>>Speed at
>>Indicated                               Approximate
>>55 MPH.                Tire             Diameter (inches)
>
>>55                     185/80/15        26.6
>>60                     185/65/15        24.5
>>56                     205/70/15        26.3
>>59                     205/60/15        24.7
>>54                     215/70/15        26.9
>>57                     215/65/15        26.0
>
>
>Shouldn't the figure in parentheses in that formula be reversed?
>
>i.e. : (Replacement Tire Diameter/Original Tire Diameter) x Indicated Speed
>
>Larger diameter means larger circumference means more travel per
>revolution;  so you're going faster, but the speedo doesn't know it.

Absolutely, they should be reversed.  My Bad.  If you will notice the
numbers in the chart are correct, I just typed the formula wrong.  The
shortest tire in the chart reads the highest speed at a given RPM.

So Long,

Darrell Leach,   KD6LRC   DM-15,   Ridgecrest, Ca
  email: Triumph_TR4@ridgecrest.ca.us
         http://www.ridgecrest.ca.us/~token/PAGE1.html
1962 TR-4 (CT5368LO)  Everyday
1962 TR-4 (CT13108L)
1965 Spitfire Mk 2
1967 Spitfire Mk 3   In work, lots of 1500 stuff
Keeper of the TR-4 List, Version 2.0 availible.



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