I have A 98 grand prix and am thinking of buying some 18" falken tourqe 5 rims for it. They are used but are in excellent shape, they came off of a Mitsubishi eclipse and the lug pattern is the same. They have tires on them which are a about 60%. He wants 0 for rims and tires, is this a good deal? Also, will the size difference mess with my gear ratio or slow my car down or possibly hurt my tranny? please give me details on what will change.