Well first of all they may be crappy tires but other reasons could be as follows:
The alignment may be off there is if you look at a tire from the front and turn it either way then that is alignment, if that is off then the tires will wear faster and make noise.
It could also be the camber which is where if you look at a tire from the front and lean it to one side or the other then that is camber..if that is off the tires will wear faster too.
Take it to a firestone or something and they can check it for you which shouldn't cost anything for the initial check, and if it is an alignment issue then i think its about 70 dollars per axel. I am not sure how to fix camber but i know that they can do it.
115
18% of 23000= 18% * 23000= 0.18 * 23000= 4,140
It is 23000, exactly as in the question.
It is 23000.
25% of 23,000= 25% * 23000= 0.25 * 23000= 5,750
23000 + 1000 = 24000
It is 23000.
It is 23000.
It is: 2% of 23000 = 460
23000
23000
23000