Facts as I understand them.  (I have a 4 door Silverado)
27% VLT for entire vehicle.  
IF factory tint rear windows (usually 20%) than no window tint for the front windows. (1995 legislature valid for 2017)

So given that I have factory rear tint, I am not allowed to tint front windows legally.

Question is then:

Is this an archaic law that is not enforced?

Is front window tint probable cause to be constantly pulled over?

I talked to a window tint installer and they explained the above and added "this is a cash only transaction" which sound dubious...

I live in the Springs area if this makes any difference.

Is it PC to get pulled over? Sure, but I've never gotten stopped for it nor have any of my friends...but then again I don't give cops other reasons to pull me over.

Buddy of mine got a ticket for window tint a few years ago.

I think it was in Boulder.  Don't know if it was local or country.

I've been pulled over a couple of times in the last few years (speeding and a cover on my license plate).  Cop never cared about my tint.   It's one of those laws that can be enforced, but most cops turn a blind eye to it.

I have 10% on three sides, haven't had any issues. I've been stopped once, I just moved to the state, was lost and it was 2-3AM so driving somewhat suspiciously, they didn't mention it.

Its not really enforced at all. I have 20% all around including the front windows and have never been pulled over for illegal tint. I've been pulled over for speeding and cops have never said anything about my tint. Colorado is closer to the sun and you can feel it in the summer. It gets HOT and to not have tint on your car isn't something I would advise. It gets hot enough here that I've seen cars with warped dashes. Just get your windows tinted, you'll be fine.

This is my experience as well.  The cops were giving me the stinker every time we passed,  and if they saw me at night l was getting pulled over.  Failure to signal and no license plate light were the common excuse.  Not one word was mentioned about the front windows betting tinted.  

I think there must have been a hoodlum driving a similar car at the time.

I had 20% for 5 years, never pulled over for the tint despite speeding alot. That said, i found 20% to be way too dark at night time in general. Im gonna go with 25 or 30% this next go around.

It's just used for "probable cause" if they can't justify their hunch and for stacking charges once you're in cuffs.