A 17 inch tire will not fit a 15 inch wheel, and vice versa. If your cobalt was a 5 lug, then yes the wheels may be interchangeable since Cobalts with 5 lug were 5X100 and so were the 6th gen Malibu. The 15s may not fit the Malibu though. Base models Malibus did come with 15s, but I’m not sure if it came with 17s, it may have larger brakes and not fit 15s. You will be putting too small of a diameter tire on the Malibu if using 195/60-R15 tires though. The Malibus with 15s used 205/65-R15 tires. You will lose 1.3 inches of diameter, it will be very noticeable that you have the wrong size tires on the car if you do so. Also your speedometer will be reading the incorrect speed.