Tint laws are more like guidelines, but you should still know them for your state. In my state, you basically cant have any tint that doesnt come from the factory. However, Ive been skating around with 25% on the front windows and 15% on the back for over 2 years. Cops have even been behind me or pulled me over and never mentioned it. I like to think its because my car looks so good with it

And I have an excellent driving record (mostly get pulled over for dumb stuff like dirty license plate, light out, lady cops trying to get my number

)
I did however have to get an inspection for $175 under the table since most shops wont risk their license.
There are some states where tint laws are strictly enforced and others where they arent. I know of many people in my state who got tint tickets, but most of them had limo tint, or are just asshole drivers.
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2009 MGM Corolla S -
My Garage
Debadged, Hood Dampers, Takeda SRI, 25/15 Tint, LED Dome/Map/License Plate Lights, Weathertech Rain Deflectors, Hella Supertones, Pioneer Premier AVIC-F90BT, 2 12" Pioneer Premier 1200w subs, Magnaflow Exhaust, TRD RSB/FSB/Springs, 18" Enkei EKM3's