IRR (infra-red rejection) is much more important. I can feel the heat on my face and head from the driver's door window and glass roof. Does the factory glass block anything?

UVR (ultra-violet rejection) is also very important. Not only to protect the car's interior from damage, but my exterior as well! I've heard (but no confirmation) that the laminated glass of the windshield and roof block nearly all UVA and UVB. What about the side windows? (Glass in general does a pretty good job with UVB, but not UVA.)

It's a no-brainer for me to tint the front door windows. It's not very expensive and has no downsides as long as I stay above 35% VLT (MA law). But putting film on the rear is an instant state inspection fail if you get a picky inspector! And putting film on the roof is expensive and the "unknown factor" of potential cracked glass.

When I was looking into tint I collect some info...posted it below, which might help you out.

As far as radiant heat, factory windows do not offer much protection. Ceramic tint blocks about 85% of infrared/radiant heat. Where I live there is no limit to the amount of tint one can put on the rear window as long as the vehicle has side mirrors...you could totally black it out and it would be legal, so I'm surprized they have a regulation on it where you live.

I put ceramic tint on my Cadi - 35% all around, and 50% on the already OEM tinted Ultraview sunroof, (legal is 50% on front sides, 35% on rear sides...but I have a medical note, so I could 5% limo tint if I wanted...I don't).
Even though the roof has ceramic tint, when the sun is overhead the heat that comes through is too strong for my liking, and I close the sunshade which offers the best protection from the heat.

Most manufacturer's print the tint level on the glass. OEM rear window tint is usually around 20%, side windows and windshield are about 30% (allowing 70% light transmission). Then there is the strip at the top of the windshield...?

Collated UV/OEM windows information:

" Windshields offer the most sun protection, according to an executive at Pittsburgh Glass Works in Pennsylvania. His company supplies glass to nearly every major automaker, including Toyota, Mercedes-Benz, General Motors, BMW and Hyundai. By law, windshields must be made of laminated glass, which means they're formed from three parts: two 2.1-millimeter layers of glass separated by a 0.8-millimeter piece of stretchy plastic. The layer of plastic helps windshields absorb nearly all of the sun's ultraviolet rays. Plastic is naturally good at absorbing UV rays, and can be made with extra UV absorbers to protect even more. The Pittsburgh Glass Works exec says windshields absorb 100 percent of UVB rays (which cause sunburn), and around 98 percent of UVA rays. Those UVA rays don't cause sunburn but can do long-term damage to the skin. That built-in protection gives windshields a sun protection factor - or SPF - of 50 or more, the equivalent of some of the strongest sunscreens.
Sunroofs, too, often contain UV-absorbing technology that can block around 90 percent of UV rays. But side and rear windows are a different story, and their SPF can vary a lot depending on the vehicle. Side windows are usually made from cheaper tempered glass, which is around 4 millimeters thick and doesn't include a layer of plastic. Side windows usually absorb only 65 percent of UV rays. That gives them an SPF of around 16, the same as some of the lowest grades of sunscreen."

 

I can confirm that the windshield in Lyriq and other cars is good in blocking UV because my darkening prescription glasses do not darken at all.

 

Tint laws vary widely by state here in the U.S. Some states do not allow any tint on the front side windows and many states have a VLT requirement for back side windows and rear window that won't allow any added tint given what the factory tint on those windows is.

 

When applying tint over OEM tinted glass, it will end up being a lower value than the tint percent. For 35% tint applied, my windows end up being around three percent lower - 32% and allowing a VLT of about 68%. The good thing about ceramic tint that I like is it has an ever so slight blue look to it, and from the inside of the car it is much more easy to see out of it than the same level of regular tint, Plus ceramic blocks a lot of heat (regular tint builds up heat from what I understand).


It's like that in Canada too, varying somewhat from Province to Province. What is allowed here on the two front sides is 50%, two rear sides is 35%, and no limit on the rear window. At the equivalent of 32% all around, I've never been stopped. I've pulled up alongside a black & white in the city at a light - no problem. Same with the RCMP on the highway. Personally, I think tint laws in most places are over done - too strict on what is allowed, and the areas where no tint is allowed is ridiculous imo. As long as one can see an outline of the person(s) in the front seat and the driver can see well at night, I think it shouldn't matter.

I'm satisfied with the equivalent of 32% tint from the outside and inside. Keeping the sunroof shade open makes the look from the outside a bit lighter. Love the heat and UV protection.

 

I did 25% on my front doors, 50% on the entire windshield and 25% on the panoramic roof. 90% uv/heat blocking, nationally backed tint warranty. I paid $350 from the best rated installer in a 80 mile radius of my house.

The cops in my region don't care about tint, all the cops have limo tint anyways and if I get caught I'll pay them their $40 ransom fine.

If the punishment is just a fine, then it's meant to be broken by those who can afford a better lifestyle.

 

I agree that tint laws are confusing with every state (or country) having something different. And how they are enforced if you have illegal tint varies too. In Massachusetts, you can get pulled over. And it's not just a fine. You have to prove that the tint has been removed. And you'll also fail the yearly state inspection. Sure, someone with money and doesn't care can just keep reapplying their limo tint on every window over and over, but that's not what I'm looking for.

What I'm seeking in this thread is; what does the factory glass provide?

I looked closely at the stamps in the corners of each window, hoping it would give specs for IRR and UVR. It only provides the type of glass, manufacturer, DOT and other codes, and the VLT percentage. However, based on that, I can glean this info:

(At least on my specific '25 Lux2)

Windshield is laminated, acoustic glass with at least 70%VLT. So we know how dark it is (70%ish) and the fact that it is laminated means it's blocking all or nearly all of UVA and UVB due to the nature of just how laminated glass works. The only question unanswered is how well it blocks IR (heat).

Front doors are also laminated, but not acoustic. Also with 70%VLT. So also blocking UVA and UVB.

Rear doors are tempered and 20%VLT. So they are much darker, but don't have the same level of UV rejection. Glass by nature will block UVB (which causes sunburn), but lets a lot of the UVA through which causes longer term skin damage and hardening/cracking of plastics and materials.

The rear hatch is the same as the rear doors, except the VLT is listed as 18.5% +/-2%.

The thing that surprises me most is the roof glass! It is only tempered, not laminated. Not only does this mean it's not blocking UVA, but it's also going to shatter into small shards and rain down upon you if broken. Unless you can somehow have glass listed as tempered but also have a lamination layer to prevent that. Oh, and it's VLT is 20% too.

So no clue what the IR rejection (heat) rating is. The only way to know for sure would be to use a two-piece meter. But every tint shop I've called only has the kind that slip over the edge of an open window. And I'm not paying $250-500 for one to use once out of curiosity.

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As an interesting side-story, back in my 30s-40s, we owned a black VW Passat wagon. That was still in my car modding days. I had it lowered, big wheels, chip-tuned, and of course tint along with some other visual mods. The tint was 35% on the door windows (legal) and 20% on the wayback windows (also legal-ish). Never had an issue with cops or inspections. Until one day, after having had the car for 8+ years, a cop sitting next to me at a light decides to pull me over for "dark tint". I'm pretty sure he profiled the car and was hoping to catch someone other than a 40-something year old dude and his wife driving home from work! Anyway, demanded to know who did the tint and started lecturing me on how it was illegal. I told him I've had it for 8 years and never had a problem. He pulled out his meter and it said... 35%! All flustered, he blusters to me that I should expect to get pulled over all the time and sends me on my way. He was the only cop to ever pull me over for tint.

 

acoustic glass with at least 70%VLT. So we know how dark it is (70%ish)

70% VLT means it is letting in 70% of outside light.

The only question unanswered is how well it blocks IR (heat).

Answered, but to repeat...not too much...see video below

Also with 70%VLT. So also blocking UVA and UVB.

70% VLT does not mean it is blocking UVA/B.

Rear doors are tempered and 20%VLT. So they are much darker, but don't have the same level of UV rejection

See above. Rear sides and front sides both don't block much UVA/B and even less heat. See my post # 2, but generally (depending on manufacturer) they block about 35% (or less) of UV rays, where tint blocks about 99%.

roof glass! It is only tempered, not laminated. Not only does this mean it's not blocking UVA, but it's also going to shatter into small shards and rain down upon you if broken. Unless you can somehow have glass listed as tempered but also have a lamination layer to prevent that. Oh, and it's VLT is 20% too.

20% VLT means it lets in 20% of outside light.
The Panoramic roof is designed to shatter into small pieces instead of shards. Shards would cut a person up like a knife.

So no clue what the IR rejection (heat) rating is. The only way to know for sure would be to use a two-piece meter.

See video

 

70% VLT means it is letting in 70% of outside light.

Answered, but to repeat...not too much...see video below

70% VLT does not mean it is blocking UVA/B.

See above. Rear sides and front sides both don't block much UVA/B and even less heat. See my post # 2, but generally (depending on manufacturer) they block about 35% (or less) of UV rays, where tint blocks about 99%.

20% VLT means it lets in 20% of outside light.
The Panoramic roof is designed to shatter into small pieces instead of shards. Shards would cut a person up like a knife.

See video

Yes, I should have been clearer (pun not intended) when I said "how dark". 70% VLT = 30% dark, 70% light coming through.

IRR or heat rejection depends on the glass. Audi sunroofs block a lot of heat right out of the factory. I was shocked how much heat was coming through the Lyriq glass roof after having had Audis for the past 10+ years! But yeah, most car glass blocks minimal IR. But it does block some. We just don't know exactly how much.

I was not implying that 70% VLT blocks UV. They are not connected in any way. What I did say was that the Lyriq has laminated glass on the windshield and front doors, which also happen to be 70% VLT. The fact that they are laminated means they are blocking pretty much all the UVB and most UVA. Unfortunately, all the other windows (rear doors, rear hatch, glass roof) are tempered and not laminated, so they will not block as much UVA.

In the old days, auto glass would break into large pieces and was very dangerous. Tempered glass shatters into small shards (granules/pieces/bits) or whatever you want to call it. Laminated glass, like the windshield or front doors on the Lyriq will shatter but remain in place, held by the film inside. The tempered glass roof would break into a million small pieces and rain down on you since there is no film inside the glass to hold it together. Those small bits are still sharp and have a nasty habit of getting imbedded in your skin! Not as dangerous as having an 8" sword of glass sever your artery. But a nuisance and a hazard, nonetheless.

 

As you said, there can be a lot of variance between manufacturers on the amount of UV and light transmitted. There can also be variance between models and years...one glove does not fit all apparently.

2024 vs 2023 Lyriq Panoramic roof:

'According to GM, the new power panoramic dual-panel sunroof incorporates a tempered glass construction, as compared to the laminated construction of the fixed panoramic roof equipped by the 2023 Cadillac Lyriq. Both features permit the same amount of visible light transmission into the cabin, or roughly 17 percent. However, the available power panoramic dual-panel sunroof allows a higher level of UV light transmission, up to 10 percent, as compared to less than 2 percent UV light transmission transmitted via the fixed panoramic roof'.

GM Link

 

Great info! Thanks. Curious why they chose to switch from laminated to standard tempered on the power opening roof. You'd think they'd want laminated glass on the roof with its higher UV blocking properties. Yet I'm sure they went with tempered because it costs less, and beyond the first model year, GM was looking for ways to cut costs on production. Especially with the added cost of the motors and mechanisms of the power roof.

 

Hope this inspires you to go dark.