Beginning in 1998, Toyota introduced side airbags as optional equipment. Toyota does NOT recommend replacement of original seat covers with non-Toyota leather or other seat cover materials on vehicles due to the following: Seat covers NOT recommended by Toyota may affect side airbag performance, in general or in part, during an accident. Modifications that negatively affect side airbag performance can result in severe occupant injuries. Seat covers are an integral part of this safety system. Replacing fabric seat covers with non-Toyota leather or other seat cover materials may compromise the effectiveness of this safety system. The design of the seat is complex, integrating safety and strength with comfort and luxury. Toyota strongly discourages modifying original equipment seats that have optional side airbags. Additionally, Toyota strongly advises against the installation or use of aftermarket seat covers, which could impair the performance of the side airbags in the event of an accident.