How do you choose a tint film to protect my car primary from heat?

I want to protect my car from heat, and I am thinking to buy a tint film. But there are so many price range and darkness of films. Which darkness or price protect the most from heat? Also, I am thinking to buy one from the Walmart, but should I go to car dealer or somewhere to get a better one?|||best thing to do is to go to your local car tinter, and tell the to do the darkest legal tint.|||Best question i ever seen that a good one well from my experience check around from a few shops and see what they say and keep your information to your self don't say well the last guy said you know, OK then you should come up with a good person, make sure you want to ask about a written warranty, good luck|||Percentage Numbers represent amount of light transmission.


Example : 35% means 35% light transmission.


Also known as VLT or Visible Light Transmission.


Film - Amount of light that is required to pass through window film.


Example : 35% Film means that the film must pass through at least 35% visible light.


Iowa


AS-1 / NO / ANY / ANY / Unknown





Note : A pending bill in the legislature would mandate light transmission on all windows of at least 70% (Basically no aftermarket tint allowed). Puts the federal window tint regulation into state law.





Enforcement Note : Iowa is spotty on enforcement but can enforce the law against out-of-state motorist such as writing a fix-it ticket.


Net - Amount of light that is required to pass both the car window and the tint film.


MPV - A vehicle such as a recreation vehicle such as a pickup truck including GMC Suburbans, Nissan Pathfinders, Extra Cab Trucks





When info is given, it is in the format of :


Windshield / Front Side Windows / Rear Side Windows / Rear-Back Window / Year Passed


Where :


NO - No Film is Allowed


ANY - Any degree of tinting is allowed


AS-1 - On the windshield, there is a mark that says "AS-1" toward the top that defines that the tint cannot go below.


UnDef - Nothing defined in the law.


FMVSS 205 - A regulation that is found in the Code of Federal Regulation. The regulation is found in 49 CFR 571.205


35 % Film - Light that is measured on the film alone


35 % Net - Light that is measured both through the film and car window|||5% limo all around, lol.