Window tint question

[jchunter13]

Couldn't find a thread covering this question. I'm wanting to tint my front windows but trying to stay legal. In Illinois, the legal tint is 35%. Seems simple to just put 35% tint on. However there is already a 75% oem tinted windows. How much darker than 35 would it be if I tinted over the 75?

[ford4thot]

110%

[Logan03CO]

Originally Posted by jchunter13

Couldn't find a thread covering this question. I'm wanting to tint my front windows but trying to stay legal. In Illinois, the legal tint is 35%. Seems simple to just put 35% tint on. However there is already a 75% oem tinted windows. How much darker than 35 would it be if I tinted over the 75?

Easiest Method: Go to a tint shop & tell them what you are after. lol
Accurate Method: (VLT value of glass) x (VLT value of tint) = Final VLT value.




Full explanation ("Borrowed from the internet"):
"Regardless of the application, all window tint film is measured by the materials visible light transmission levels (VLT). The VLT value is the percentage of visible light the tint allows through from the exterior of a vehicle, building or home to the interior.

The lower the VLT percentage, the darker the tint is and the more outside light it blocks. A window tint that has a VLT value of 5% indicates that the window film only permits 5% of the exterior light to pass through it, while a film with a 50% VLT value allows 50% of the light from outside to pass through."

While many might assume that the VLT of a window tint is the only factor to consider when calculating the final VLT of installed window tint, there is one additional aspect that must be considered.

Every piece of glass, regardless of the application, blocks a certain amount of light. As a result, glass also has its own VLT value, which must be accounted for in order to determine the installed window tint’s final VLT value.

For example, if a state law indicated that the lowest legal VLT value for a tinted car window was 30% and an individual were to install a window tint with a 30% VLT rating, the windows final VLT rating would actually fall below the legal limit because of the window’s natural VLT value.

Because of this, window tinting professionals use a simple formula to calculate the installed window tint’s final VLT value:

V1 (VLT value of glass) x V2 (VLT value of tint) = V3 (final VLT value)

Let’s assume, for example, the legal limit for the window tint of a vehicle is 30% and the vehicles glass has a VLT value of 75%.

In this case, since we already know the VLT value of the window and the final VLT value we want to achieve we simply need to rearrange the formula to calculate the proper tint to install as follows:

V3 (final VLT value) ÷ V1 (VLT of glass) = V2(VLT value of tint)0.30 (30%) ÷ 0.75 (75%) = .40 (40%)

According to this formula, installing a window tint with a VLT value of 40% will result in a final VLT value of 30% as desired.

Professional installers using this formula save their customers a significant amount of money not only in traffic tickets for illegally tinted windows, but also in the reinstallation of window tint which most traffic courts require when a driver receives a ticket for illegally tinted windows."

Source: http://www.slideshare.net/MarcBeck/u...t-transmission

[Tom]

Are you sure you actually have 75% tinted windows? It varies by manufacturer to manufacturer but windows by nature are already around 70-80% or so. That's why when you roll down your window more sunlight comes in. So I'm skeptical that someone went through the time and cost to add what would essentially be a clear tint to your vehicle.

[Logan03CO]

Originally Posted by Tom

Are you sure you actually have 75% tinted windows? It varies by manufacturer to manufacturer but windows by nature are already around 70-80% or so. That's why when you roll down your window more sunlight comes in. So I'm skeptical that someone went through the time and cost to add what would essentially be a clear tint to your vehicle.

I just took it as meaning (implying) the 'factory glass' has a VLT of 75% - but I may have been reaching. lol

[jchunter13]

I'm guessing it is 75%, but I could be wrong. It says carlite tempered dot 75 on the front two windows

[Logan03CO]

Originally Posted by jchunter13

I'm guessing it is 75%, but I could be wrong. It says carlite tempered dot 75 on the front two windows

That's the DOT number that is assigned to the manufacturer of the glass.

DOT75 = Ford Motor Company Dearborn, MI, USA

Source:
http://www.carwindshields.info/windshieldmarkings
http://www.carwindshields.info/dot_db

[jchunter13]

So if that's the dot #, any ideas as to why it says solar tint. There is definite a slight tint to them now

[Logan03CO]

Originally Posted by jchunter13

So if that's the dot #, any ideas as to why it says solar tint. There is definite a slight tint to them now

As Tom indicated - Most glass is produced with at least some 'tint' to it.

Most obvious example is extended cab glass - It's 'tinted' but isn't a removable surface setup like aftermarket film.

The 'film vs. factory' angle doesn't fundamentally change your original question.

As you mentioned - The stated legal limit of xx% also needs to account for any & all glass properties. They slap a meter on the glass & measure it's VLT percentage.

AKA - If the legal limit is 35%, technically you could never run 35% tint & be legal due to the factory traits of the glass.



If your area is anywhere like around here - running 35% tint in combination with factory 'clear' glass wouldn't get a second look (assuming a 35% State). It's the guys that slap 5% on that draw the attention.

States that have yearly vehicle inspections for 'safety' - might be a different story if they actually use a meter.