On Mon, 25 Jun 2018 18:47:14 +1000, "Jeff" wrote:



"Chris Hogg" wrote in message
.. .
On Mon, 25 Jun 2018 15:50:06 +1000, "Jeff" wrote:



Yes, but it is the distance between the axle and the road
that determines the rotation rate.

If the length of the perimeter of the tyre is say 1.5 metres, and the
vehicle is travelling at 150 km/hr, that means the tyre rotates 100000
times per hour, or 1666.6 rpm, assuming no slippage between tyre and
road or tyre and rim. There's no getting around that, and there's no
mention of state of inflation, shape of the tyre or axle to road
distance.

Yes, but it is the distance between the axle and the road
that determines the rotation rate.

When considering this sort of thing I first consider the real world
facts.

iTPMS systems obviously work.

I believe the regs for such systems state that they must warn the
driver of a pressure lost *before* it passes 25% of the pre-set
pressure.

This means that it must be accurately measurable so when a 32 psi tyre
drops it's pressure to 24 psi (23?), it should raise the alarm.

The instructions for calibrating cycle speedos require you to measure
the *loaded* rolling circumference of the wheel bearing the speed
sensor (when it would be easier just to put a tape round the wheel).

So, a right brainer would take these sorts of things and then try to
look for a scientific / mathematic solution as to why this is.

A left brainer would jump to a conclusion based on their lack of
understanding and then look for information to support their denial
(from other left brainers typically). ;-)

Cheers, T i m