With an All Wheel Drive vehicle, you DON'T want to mess too much with running different rolling diameters between axels (front and rear). 325/35/20 will put the rears at a slightly LARGER rollering diameter than the stock front, 275/40/20. Whether or not it will affect how the drive train will wear...do you really want to take a chance? Not worth the risk...just get the proper size tire.