Thickness of stock Integrity tire wall?

I seem to have very good luck in getting my tires punctured by screws. I had one tire fixed a few months ago and now I found a screw buried in the tread of another tire when I was doing tire rotation. The tread depth is about 5 mm and the length of the screw about 10 mm. I took the screw out and the tire seems to hold air, at least no big leak. How thick is the rubber beneath the tread? If it's more than 5 mm then I may not need to do anything. Thanks!

 

Update: I went to a gas station and the mechanic there thought the screw wasn't long enough to penetrate the tire. He also tested with soapy water. Now after driving and monitoring for a week there hasn't been any leaks.