White letter problem with bf goodrich tires

Why would you want to wet sand them when bf good rich says they have a problem with them and will give you a new set.They had a problem in the manufacturing of the tire.You can sand them and make them better but they will discolor again in a week.To Alan H yes they are 60 series and two of the new tires i just got are doing the same thing .They where made in 2015 i need to get 2016 tires