Which Tyres?

They generally turn a blind eye but they can fine you 20 EUROs-- 25 if they feel someone was endangered and 35 if you got into an accident. The law demands that you have "at all times" working lights (including reflectors). On random controls and dragnets (usually in the Spring when the masses haul their bikes out) they tend be on the lookout for standard push-bikes and supermarket MTBs but if the officers don't like the way you look or ride and "suspect" that the bicycle is perhaps unsafe...