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MNBoxster · 09-25-2005, 03:44 PM

@Grease,

Thanks for the explanation. After my post, I thought it must work something like this, it's the only way. I was thinking in terms of actual RPMs of the Tires, not Rolling Radius which is actually a measure of the force imparted on a tire due to bumps and lateral forces and transmitted through to the driveshaft. RR is always VERY close to the actual Circumference, but always slightly less. But, most the variables which affect Circumference will also affect the Rolling Radius.

But a couple points. This system is a comparative system, meaning that it cannot detect actual pressures, it merely detects the difference of the force transmitted between one tire and [u]another[/i], not all four as you earlier mentioned. This difference equates to a difference in Tire pressures. I wondered about this especially.

I suspect it compares it's mate on the same axel, or it cannot adapt to differing Tire Widths which many people install (on the Rear to increase Traction, on the Front to induce greater/lesser Understeer).

Overall, it's a slightly less accurate way to monitor the tires. Both Tires could be underinflated to the same degree and the Monitoring System wouldn't detect it. But, I concede this is unlikely.

I think the trade off is that there is no need for a transponder and receiver, and I can see where this might be benefitial, certainly less complex.

Thanks for the enlightenment!

Happy Motoring!...Jim'99

09-25-2005, 03:44 PM	#12
MNBoxster Registered User Join Date: Sep 2005 Location: Minneapolis/St. Paul, Minnesota, USA Posts: 3,308	@Grease, Thanks for the explanation. After my post, I thought it must work something like this, it's the only way. I was thinking in terms of actual RPMs of the Tires, not Rolling Radius which is actually a measure of the force imparted on a tire due to bumps and lateral forces and transmitted through to the driveshaft. RR is always VERY close to the actual Circumference, but always slightly less. But, most the variables which affect Circumference will also affect the Rolling Radius. But a couple points. This system is a comparative system, meaning that it cannot detect actual pressures, it merely detects the difference of the force transmitted between one tire and [u]another[/i], not all four as you earlier mentioned. This difference equates to a difference in Tire pressures. I wondered about this especially. I suspect it compares it's mate on the same axel, or it cannot adapt to differing Tire Widths which many people install (on the Rear to increase Traction, on the Front to induce greater/lesser Understeer). Overall, it's a slightly less accurate way to monitor the tires. Both Tires could be underinflated to the same degree and the Monitoring System wouldn't detect it. But, I concede this is unlikely. I think the trade off is that there is no need for a transponder and receiver, and I can see where this might be benefitial, certainly less complex. Thanks for the enlightenment! Happy Motoring!...Jim'99