Sorry for bothering you. You are the only one who comes to mind when asking about glass thickness. Maybe thebiggerthebetter will know, especially since the guy owns a two ginormous 4500 gallon tanks.Lol. I dont know, never tried anything near that big. Never seen a glass aquarium that size either.
Just as a frame of reference...the "typical" safety factor usually quoted for glass aquarium manufacture is 3.8; the glass aquarium maker I worked for back in the 1970's insisted upon no less than 4, and preferred to shoot for 4.5 or greater.Well into the realm of commercial, non-DIY tanks with this question and rarely are tanks that size made out of glass.
The safety factor on 25mm tempered float glass, fully braced, for that size window is about 1.5; the safety factor on 40mm glass is 3.0 for what it's worth.
Gamble accordingly.