[SteveC]

For the more pedantic let me be more detailed and precise:

Some German autobahns without speed limits and many with speed limits of 120 or 130kph have conditional speed limits of 80kph Bei Naesse, which means 'when wet'.

You see these signs everywhere, throughout the entire country. My point is, many roads that authorities are prepared to leave unlimited when dry, carry a conditional speed limit of 80kph when the surface is wet.