I was in the business for 18 years...
Generally yes the drivers and passengers windows have a limit as to how dark they can be tinted..it all depends on what state you live in.
Most states that have laws regarding window film coating will only allow you to apply 35% (which is a light tint) to the 2 front door glass. a few don't allow anything and some allow up to 20%
whatever your laws are ..don't go darker than 20% on the front door glass..you will have problems seeing at night.
if you want the remainder to be darker..thats ok and will shade the interior making it appear darker as well.
this site has a page with the laws on it along with other info you might be interested in (it's not my site)
http://www.tintdude.com/laws.html