Driving in the rain can be a treacherous experience but finding the right wet weather setup can help make it a lot less hazardous.
Wet weather car setups are all about maximising grip, both mechanical and aero. You want the highest wing settings and the softest springs you can run while maintaining your car balance. Ride height is critical here too, but in the opposite direction of a dry weather setup. Too little ground clearance and the bottom of your car is splashing through puddles. Also, very soft spring settings makes a low ride height not very good.
- Increase front and rear wings by at least 2 clicks (if possible)
- Reduce brake pressure and size of discs
- Increase gear ratios (move to right)
- Soften roll bars and springs
- Raise ride height
Basically you want to set your front and rear wings to 11 and raise your ride height to 11 front and rear. Also run the lowest braking pressure, to avoid lockups. You can also save some weight by reducing the size of the brake ducts. Because it's raining and likely cooler, you don't need them so large. You're also not generating as much heat in your brakes becuase you cannot brake as hard.
Perhaps the most crucial to a driveable car is gear ratios. Here you can either use the same gear ratios as in the dry, but short shift, or you can select really long ratios and minimise torque and therefore wheelspin. My preference is to go long gear ratios because I like to see all the pretty lights on my wheel and it saves some effort in paying so much attention to that area.
Anti-roll bars should be set to be softer. Softer roll bars will help the car with mechnical grip. In the dry softer rollbars give more grip but less steering response, as the car basically wallows around. This isn't so much a problem in the wet because grip is so much lower already.
The strategy for developing a setup for the wet is pretty much the same as the dry. Make adjustments to one component at a time pay attention to it's effects.