Ok, I have an 08 550i with tinted windows. My Real Time Traffic Information (RTTI)in the NAV doesn't work. The dealer is blaming it on the window tint. I think this is absolute BS! Anyone have rear window tint and use the real time traffic with NAV?

These dealers will find anything to avoid fixing the problem.

 

That's a total BS!!! You should go talk to another SA at a different dealer.
The Real-Time traffic info is received via the satellite signal (I am assuming you have Sirius service). The satellite antenna is embedded in the shark fin antenna on the roof and not the rear glass. Even if your rear window is tinted, it should only interfere with your AM reception and not so much your FM reception. There's also an antenna amplifier hidden under the pillar on the right-rear. It can be accessed by removing the high-mount brake light cover and the interior trim on the pillar.

 

actually thats possible. when i got mine tinted, they told me i cant get the a specific tint because it messes with our cars electronic signals. it think is the metallic kind of tint or something. i wanted that one too since it blocks a lot of heat/uv rays. but since they told me that, i think i pick the next level after it. so its not really bs, its only bs when you dont have the metallic tint

 

I guess there are various opinions out there but I have metallic film (35% tints) all around on my cars (E60 & E65). The E60 doesn't have the satellite but my E65 does. If I obstruct the line of site to the shark-fin antenna, the satellite signal cuts out. It's a simple test really. Just drive your car into your garage or a parking structure with a roof, your FM signal won't cut out but your satellite will just as soon as the antenna is not facing the open sky.

 

this is definitely a possibility if you have metallic tint, its been known to interfere with cellphone reception as well. the best option for tint is the ceramic tint, it has the same characteristics as the metallic tint but doesn't cause interference.

 

They say the RTTI works through the FM signal, not the Sirius. I think the Pre 08 cars worked through Sirius. The car came tinted, so I'm not sure what type of tint it is. How would I verify? Though it still seams like BS, cause the FM radio still works...

 

well from what i understand, if your back window is tinted the antenna of the fm radio is outside the tint. looking from the inside it should be tint then fm antenna then glass. you know, those aztec pattern looking things at our back window. from what i understand though. i could be wrong. dont know how to check it, maybe you could go to local tint shop and see if they can tell, or ask bmw since you bought it tinted.

 

You are partially correct, the RTTI info is transmitted in the FM bands. While the copper lines on the rear window are part of the antenna. Placing a metallic film very near to them will detune the antenna to the point where it no longer works. This is true with any antenna.

By using metallic tint on all the windows you are effectively creating a Faraday Cage (link) inside the car, no RF signals can get in or out.

--- Yes I used to be an antenna engineer.

RTTI info is usually much lower power than standard FM, so if stations are weak (due to tinting) the RTTI may not work.

Does your car have HD radio? If this cuts out frequently or FM switches from mono to stereo often it is very likely a radio reception issue.