I understood they were compulsory on over 3,5 tonnes so you should use them maybe the Police would not stop you without them BUT they would have
INSURANCE complications if you ever had an accident with a CYCLIST or Motorcyclist so why take the risk as you have already bought them , same applies to the speed restriction stickers , and has any one bought the new warning light for breakdown etc in Spain apparently when this is activated it signals the POLICE your location as well as warning other drivers of your breakdown , I was told this by the Police that attended our Tyre Blowout homeward bound from Portugal , the warning TRIANGLES are no longer valid but I will still use them in addition to the NEW LIGHT warning when I next go Foreign