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Registered
Join Date: Nov 2001
Location: San Diego
Posts: 39
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Speedo Calibration
Anyone know the speedo error created when 205/60/15 series tires are put on the stock rims? I'm guessing it must be around 5-8% but would really like to know.
Also, does anyone offer recalibration services with 60 series tires? Thanks for the help. |
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11-16-2001, 12:10 PM
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RETIRED
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Nort Hollywood Speedo...advertises in Excellence and has a website.
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1983/3.6, backdate to long hood 2012 ML350 3.0 Turbo Diesel |
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11-16-2001, 12:51 PM
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Here ya go:
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Rouser! |
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11-16-2001, 01:22 PM
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Registered
Join Date: Dec 1969
Location: chula vista ca usa
Posts: 5,700
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You might want to download the GEARS.EXE program I wrote from the PP site here. You get the transmission ratios and final drive ratio from the owners manual then measure either the tire diameter, circumference or number of tire revolutions per mile and enter all the data and you'll get exactly what the tach vs speed is. The easiest thing is to mark the tire while on the car and move the wheel one revolution and see what the circumference is. It is used by several shops I know of and they love it. Or you can guess? Good luck.
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11-16-2001, 04:27 PM
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Join Date: Jan 2000
Location: Allen Park, Mi, USA
Posts: 235
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I downloaded the gears.exe program and found the gear ratios, and final drive ratio to plug in. I also measured my tire circumference. Here's what I don't get: It asks for the tire diameter, or circumference, or revolutions per mile. It doesn't seem to me that these numbers would be interchangeable in the equation. Could it be that the values are so different from each other that the program recognizes what the measurement must be by its value and calculates accordingly, or what?
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11-18-2001, 01:31 PM
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Registered
Join Date: Dec 1969
Location: chula vista ca usa
Posts: 5,700
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Sorry for the confusion, but the three numbers all equate to the same thing, I.E. how far the car moves for one tire revolution. The numbers are different enough that I have a check to see what the range of the number is and then calcs accordinly. I like the measured circumference since I think it is the most accurate. BF Goodrich lists the number of revs per mile and some might like to use the spec given by the manufacturer for diameter. Good luck. If you have any problems you can give me a call at 619-691-8640 evening or 619-544-7513 days.
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11-18-2001, 06:26 PM
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Registered
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Hey Ya'll try this site: www.miata.net/garage/tirecalc.html
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11-19-2001, 07:24 AM
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Da cab
1973 Porsche 914 
74 Porsche 914 2.0L 
