How to change strategy (tires/fuel) while in-race?

So yesterday I had a race when it started lightly raining and I was thinking of changing to intermediates but wasn't sure how to once the race starts.

Well, you just have to drive into the pit.

Then, go to the cocpit-view (if you haven't already),

press the throttle-key (keyboard or steering wheel) until the cursor it marking the tyre choice,

thereafter, just steer to the right (keyboard or steering wheel) to chose intermediate or full wet tyres. [steer to the left if you want to change from rain tyres to inters or back to slicks once again]

Finally, press space-key (keyboard, have a look at your steering wheel settings to get what kind at your steering wheel it is!) to confirm your choice.