From what I’ve seen on a few recent VRS models, the factory rear glass usually sits around the mid-20% range once you account for the slight tint that’s already built into the privacy glass. If you felt that 30/35% on your Tiguan wasn’t dark enough, going with 20% on the rear of the VRS should give you that deeper look without hurting visibility, especially at night. When I had mine done locally at OC Tint Solutions, they mentioned that a lot of VRS owners end up choosing a mix similar to what you’re considering 20% rear, 30% rear doors, and 50% on the fronts, mainly to keep things balanced and legal. They also shared a few comparison photos that helped me decide. If you want to check out examples or get a better idea of how those percentages look in real conditions, their website has a gallery with a bunch of setups that are pretty close to what you're planning. It might help you visualise the difference before committing. Hope that helps, 20% on the rear definitely seems like the sweet spot for the VRS.