Rain milimeters in track VS Wet tyres

At what milimeters of rain in track it's supposed to fit the Wet Intermediate tyres and the Wet Full tyres?

1mm - Int or Full?
2mm - Int or Full?

3, 4 and 5mm - i guess is certainly Full

I usually go onto wets at 2mm and that works well but any less than that and you are screwed

how can you tell before the race how much water is on track?because it just says rainning but i dunno how long it been rainning for to see how much water is on track.

Below 0.8 go for ints. Above that, wets.

I agree with Steve Dee, anything higher than 0.5mm I go approx 1 more lap an pit.

It pays to an active manager an I ran into a situation yesterday where I was actually out of Full Wets in a race since I'm in a league that is 100% race distance.   I never adjusted fuel to match tyre wear so I had no choice to go to inners an lost approx 4sec a lap for the remainder stint. 

BD

It's dry until 0.20mm and intermediates for 0.20mm to 4mm. It's wets for 4mm and up

I think you meant intermediates from 0,20mm to 0,40 mm.
Not from 0,20mm to 4 mm .... otherwise you loose 10 to 20 secs per lap, depending of how much water and circuit.

http://igpmanager.com/play/?url=race-result/442910#race

My driver:- Leo Lambert  (qualified on full wets while everyone else was on inters)

For this race, I set my advanced strategy to fit wets when water is over 4mm and it was raining before the race. I qualified on wets and could get pole which i couldnt in other races. Then when i was waiting for the race to begin, therain stopped and water started drying from the track. It mightv'e been some 4mm at the start down from 5mm initially. I was testing out the wet tyres while everyone else was on inters.  In first 3 laps, my times sucked (by 5+ secs) inspite of decent tyre temps which I thought was down to the tyres. Water started going down to 1mm in 3 laps and I thought inters mightve been ideal for that range. And with that rate of water receeding, I expected it to dry up in 1 or 2 laps at max, but the water level became almost stagnant in the 0.5 range. And obviously my race went down and I quit it. What i learned from my second(soft) stint is that pace is almost similar on softs until 0.1~0.2mm and doesnt require a pitstop. And from my initial stint, I concluded that full wets are ideal from 4+mm. Some of the bad lap times might be down to track specific elements but not entirely. 

Thats what I learned from my experience though. Feel free to correct it.

And I was watching at track water level from the weather forecast in the viewer. I dont think I have any idea about the older version or how it operated.

Jack, today I had my first race in rain. The track was soaked the whole race: beaker fully blue. On the left of live weather below the temperature it said Wet: 1,00

1.) I guess this is the number everyone is talking about in this thread.

2.) Why is it 1,00? Acording your explanation it should be 5,00
It that where your confusion is coming from?

The 1.00 is one centimetre I believe.

Nope. After the race I left the race screen open. About 30min later the value was dropping:
half beaker (2.5mm) = Wet: 0,50