OEM Navi and Larger Tires (OK?)

[Hal]

Does anyone know if running 35's will cause problems with the OEM Nav system? I already know my speedometer will be affected. I'm not sure what vehicle inputs the nav system receives when calculating distance, speed, travel time and distance to go, etc. Obviously a GPS can operate with no vehicle input, but some Nav systems use vehicle input to maintain a course when the satellite signal is temporarily interrupted. I'm wondering if an inaccurate speedometer reading will also confuse the Nav system in some way.

[HummerNewbie]

Not sure what effect it will have but as I recall, the OEM NAV does receive a signal from the VSS. Maybe Fstop will know.

[f5fstop]

I will have to guess and say most of the time...no. The AVIC I installed looks at the VSS for correction, especially when in heavy tree coverage, long tunnels, cities, etc., but will operate without the VSS. However, the AVIC's main input is the actual GPS antenna.
So, not saying the factory is the same, but it is made similar to the aftermarket units. Besides, GM does not make the unit, and aftermarket supplier does.
So, if running in heavy coverage the unit might be incorrect, but when coming out of the heavy coverage, the GPS should correct itself, and the correction would be slight.
Again, just my opinion on how it should work.

More information from someone who knows this system pretty well:

The vehicle speed signal is used for greater accuracy for determining the position of the vehicle when GPS signals are unavailable.

[Hal]

Thanks for the input. It's only a matter of time before I move to the larger tires and then I'll be able to report any problems to the forum first hand. In the mean time I'd still like to hear from anyone who is running factory or similar Nav system and oversized tires.

I'm also thinking that if a programmable module becomes available for the H3 to adjust the vehicle speed signal to match larger tires, a number of issues would be resolved. As with so many modifications we want to see, we are still patiently waiting... (Amstar, Rough Country, etc... tic-toc-tic-toc... zzzzzzzz)