May I ask why you would want to change? I assume you have some of the smaller tires or can get some free or relatively cheap. The smaller tires would lower your load carrying capacity slightly, but would probably still be adequate for the Taurus. They would also throw your speedometer(as well as the odometer)off, It would show you are going faster(and farther)than you are actually going. At any rate, always keep a matching pair( same brand, style and size) of tires on the drive(front) axle to help prevent long term drive train problems. Just my opinion.