Tenerife is a very safe place, but some places can be not so safe at all. This is view points in most popular tourist places – parking lots at the Teide and Masca.
Don’t leave the bags and private things inside of the car, because many robbers wait for the tourists and very often the brake the glasses of the car and take the things inside!
All other places is safe and we don’t hear about any problems here.
Never leave photo cameras and notebooks in the cars.