I just cheked my tires and they have 1/8th of tread left, the little indicator is at 1/16th if i'm not mistaken. My question is how in much tread in % has my tire or how much wear in % it has.

 

ttt

 

Most tires come with 10/32" of tread when new. (You can look up the specs on the Tire Rack website or the tire manufacturer's website to be sure.) As you noted correctly, the treadwear indicator bars are flat across at 2/32". Therefore, the tires wear 8/32" from new to the treadwear indicator bars.

Since your tires have 4/32" (1/8") of tread depth, they have 2/32" of tread to use before the bars are flat across. Therefore, the amount of tread they have left is (2/32)/(8/32) = 2/8 = 25 percent remaining. You have already used 75 percent of the usable tread.