On Thu, 18 Aug 2005 11:52:04 -0400, Jeff Wisnia
wrote:


The "NPR "Car Talk" show's "Puzzler" a couple of weeks ago gave an
answer stating that some car's computer "knew" a front tire was low on
air because the ABS system noted that wheel was rotating "a heck of a
lot faster" than the other wheels when the car was driven.

I didn't buy that one.

Sure, the rolling radius of a low tire is less than that of a fully
inflated one, but the overall circumference, particularly on a steel
belted tire, remains the same. Barring slippage, that circumference must
lay its whole length on the road once per revolution, just like the
circumference of a full tire does.

From my TSD rallying days I remember that low tire pressures made some
slight differences in odometer measurements, but these were in the
second decimal place, hardly "a heck of a lot".

Am I missing something here? What do the great minds on rcm think about
this one?

Jeff

This is about as plain as it can be. Jeff, would you hand out those
DNRs for those who can't understand this?

http://www.desser.com/tech/centrifugal.html

Want more? Google for tire traction wave.