I got a used set of saleen replica rims, 18x9 front 18x10 rear, in the front i have 265/35/18 and in the back 275/35/18, more than 60% of life left on the tires, but after i mounted them on my mustang gt 2003 and drove, the car started to shake even more when i go in the highway, even my steering wheel was shaking, my question is can this be just the balance? Before i had cobra-r 1999 rims, 17x8, 245/45/17 and never had this problem...
Get them rebalanced. I know you can't put weights on the outside and for that matter, who wants the ugly things on it if the wheel has a lip. But, you may have to have sticky weights put close to the outer part to get a good balance. I just went through the same thing with some 18's .
balance my be the issue. if you are gonna get them rebalaced it would be helpful to call around to some of the local tire places and ask if the have a road force balancer. i work for firestone in the orlando area and we have one. the machine will not only balance better but also tell you if you have a bad wheel or a tire defect. basically any issue other than hub clearence on you car. hope this helps
1989 Mark VII LSC, OEM Bullitt wheels, Full coil spring conversion, B&M Shift kit, BBK Fenderwell CAI, Crane Cams Coil, Flowmaster Exhaust