Help with front tire selection

[Tom]

Mods- feel free to move this if you feel it belongs in a different forum

I put kumho ecsta's in 255/45/17 on the front of my 98 the same time I put nitto nt450 275/50/17's in the rear. The kumho's are already badly worn out and need to be replaced. Granted they are in front but the nittos in the rear look brand spanking new [this is about 20,000miles and 2yrs] and have a lower tread wear rating of 300 vs 330 for the kumho's. Yes I had my alignment done Did the rims/tires/suspension/alignment all at the same time. Both my 78 [5/5 drop] and my old 79 [5.5/7 drop] did not have this problem. Is it just the kumho's or will all tires wear like that when they carry a similar wear rating on these style trucks? Anyone have a better option?