I worked at a body shop that tinted a lot of trucks and cars.Don't buy cheap tint you'll regret it later.I've had 38% to limo tint on my cars and I like the lighter stuff my self as the limo tint makes it hard to see out at night,inside glare and it seemed to attract the most assholiest of Texas troopers who loved to write me up.Never had any proplems with the lighter stuff.Helps keep the temps down inside too so you don't bake your interior parts.Buy 3M or something same quaility.

This looks like a response to a different thread.
I think the usual test around here is that if you write on a sheet of paper with a normal pen you have to be able to see it through the tint.