I just put 18" rims on my 2000 GS4 w/ Nav. Do I have to make any adjustments to make sure my speedometer and NAV systems are accurate? If so can you point me to a thread or give some instruction. I know my way into the diagnistic screens.

Thanks

 

No one knows this???

 

On the Rx330, there's a button somewhere in the setup screens labeled "calibrate". This brings up another screen with a button you're supposed to press whenever you change the tires. I assume your car has a similar function.

As far as the speedometer goes, the key is that the rolling diameter of your new wheel/tire combination should be within a few % of the rolling diameter of your old combination. As long as that's the case, no speedometer adjustment is needed. In the Rx world this is never a problem because there's not room in the wheel well to increase the rolling diameter substantially. Of course, I haven't got a clue about what you've done to your car.