Had a flat tire on my 2017 sport. Mechanic put donut tire on rear. Was driving to tire shop,and the drivetrain warning lite came on. Was told at the shop that the difference in the size of the tire caused this. Why would nissan use a donut tire as a spare in 4 wheel drive cars, if this is going to happen. Tire shop said i should have stopped and let the fluid cool down. Any one else have this problem? Whats the solution? Sorry for the long post.