Any issues or concerns with having tint applied to the rear factory-tinted windows? They need to be darker.

 

No issues go ahead and do it. I had two layers of tint applied on already dark windows on my x6

The factory dark windows are just like normal clear windows so no problems at all.

 

no problem at all. The factory are just stained glass so you are putting tint on glass. I would avoid it if it was layer of film (tint) over tint.

what % are you going? I have the sunshades in the rear, so in most time i just have them up. But you are right, I feel they are a bit too light.

 

I even put tint over tint on a previous car. Only risk is that not the tint is too thick and might get verticle lines sometimes.
On the cayenne no worries tint away.
I did 18% front 30% rear and searched between 8 different brands to find a perfect match front and rear with tint color bf of the rear factory having a blue-ish color.
End result perfect front rear inside and out.
https://www.6speedonline.com/forums/...9&d=1308854772

 

Thanks. Your car looks great. What brand tint did you end up using that matched?

 

ASWF!

I compared lumar 3m suntek all kinds.
Looked similar from the outside but from the inside front to back looked different and not good IMHO
.

 

I once heard that tint on tint cancels itself out ^_^

 

do it! Mine is 10% all the way around with 30-35% on the front windshield... I love it