I just had mine done by a pretty reputable place. I guess it's time for a google search on who is correct.
So here is the final word. It looks like 25% is the legal limit on the side windows (both front doors and back doors are considered side windows) and the back window can be anything you want as long as you have side mirrors. I went to check my receipt and it says 30/30/15 - I think I may want them to re-do it. I told them as dark as legally possible which would give me 5% more
http://www.txdps.state.tx.us/vi/Misc/faq/tint.htm
What are the actual state driving laws for after-market window tinting?
View the reference in the Transportation code :
§ 547.613. Restrictions on Windows
Windshield
Glass coating or sunscreening devices
Cannot extend downward beyond the AS-1 line; or
Cannot extend more than 5 inches from the top of the windshield without an AS-1 line.
If sunscreening devices are used above the AS-1 area of the windshield, the light transmittance value must be 25% or more;
The luminous reflectance of any additional sunscreening devices used must be 25% or less;
Sunscreening device cannot be red, blue or amber in color.
Side Windows
All side windows must have at least 25% light transmittance and luminous reflectance of 25% or less, over the entire surface area of the window.
*Rear (back) Window
If vehicle has left and right outside mirrors, there is no minimum light transmission requirement.
If not equipped with both outside mirrors, the rear window must have no less than 25% light transmittance and a luminous reflectance of 25% or less.
The manufacturers installed glazing shade band is excluded.
Time to call them back and see if I can get this changed.