I ordered my wheel/tire combo last week and they are set to arrive tomorrow. I was just curious how much if any, they will hurt performance or MPG? I have a SRT Design with the 20's on it and wanted to know how much they or the true SRT-8 wheels weighed in relation to the wheels that I bought. According to the salesman, my wheels are 44lbs. for the fronts and 47lbs. for the rears. Is this good?