Profile depth on tires ?

Have a question. With my new summer tire 225/40-18 it is like that they have about 7.5-7.9mm profile depth in the middle. At the inside, however, the profile runs out obliquely. In other words, there I measured only 3.5mm. Due to the lowering, there is always a little more wear in the inside, which is certainly also normal. So let’s assume that the tire runs down normally (in the middle, outside, inside the same), i.e. everywhere 3mm wear, then the tire would be on the inside (where only 3mm wa The profile is measured in the least place,or ? So then about 4,5mm in the middle and inner edges would be 0,0mm blank tires off into the garbage. That can not be right? FG