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Speedo does not function

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Andrew Mace said:
I always wondered about "certified" speedometers one would see in police cars. Were those speedometers "recertified" as tires wore down or as they were replaced with a different brand (or possibly even size) of tire? /bcforum/images/%%GRAEMLIN_URL%%/smile.gif
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Interesting point. I read an article on one of the top Audi Sedans a couple of years ago being tested in Germany. The car was supposed to be electronically limited to 155mph. The speed sensing was done through the traction control and ABS systems so road speed is actually measured at the wheels. During the test the journalist noticed they were doing well over 155mph and asked whether the limiter was active or not. The engineers told him that the car was limited to 155 when the tires were worn down to the wear markers.

Of course, changing the tires to a non-OEM tire will affect the accuracy of the limiter to tire wear. It also shows just how much tire design is involved in cars. Especially the spendy ones.
 
But wouldn't the speed of the prop shaft be effected
by the rpms of the wheels?

d
 
I'm SO confused! /bcforum/images/%%GRAEMLIN_URL%%/confused.gif
 
Think of it in terms of what would happen if you had a ten inch wheel on your car, it has to do more revoloutions to go the same distance as the 15 inch wheel - only problem for your speedo is that it doesn't know what size wheel (or circumference tire) you have on the car and presumes that it is a stock circumference that it has been calibrated for...thus a worn tire goes less for each revoloution than a 100% tread - this is clear to me, but I had a couple of beer with lunch...
Kerry
 
The onlt thing I know for certain is:

"the wheels on the bus go round and round
round and round
round and round"

"The people on the bus go up and down
up and down
up and down"

All thru the town!!"

/bcforum/images/%%GRAEMLIN_URL%%/iagree.gif /bcforum/images/%%GRAEMLIN_URL%%/crazyeyes.gif
 
Tinster said:
The onlt thing I know for certain is:

"the wheels on the bus go round and round
round and round
round and round"

"The people on the bus go up and down
up and down
up and down"

All thru the town!!"

/bcforum/images/%%GRAEMLIN_URL%%/iagree.gif /bcforum/images/%%GRAEMLIN_URL%%/crazyeyes.gif
Click to expand...


Dale, I think this car thing is getting to you.....
 
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