20% or 35% on all five rear glass pieces will give you a great look.
It's not too dark during the day, and even at night, it's very visible.
1 - Rear Windshield
2 - Left Rear Door Window
3 - Left Rear Door Quarter Window
4 - Right Rear Door Window
5 - Right Rear Door Quarter Window
On a WHITE Yaris, I prefer the tint to be a little lighter so I would personally prefer 35% on all five pieces.
I went with 20% on all five pieces since my car is black.
But this also depends on film your installer is using.
Huber Optik and
Madico manufacture high quality films that are ceramic based.
I've included pics below to give you an idea of what 20% looks like during the day and at various angles/shades.
Relatively Clear Day, few clouds
Slight overcast
Clear conditions, sun shining directly at my car
Another angle
Another (great) shot
