Should I reduce my tyre pressures when it is wet?

No, this is a common myth.

While a tyre’s carcass will generate more heat when you run lower pressures, the adverse effect is that the tread grooves will close up, meaning water cannot be channeled away from the tyre as the tyre manufacturer has designed it to.

Wet weather grip is more about water dispersal than it is about tyre temperature.

So while reducing tyre pressure sounds like it would work and might make the tyre warm up faster, it’ll reduce its ability to remove water and it’ll increase the tyre wear.

Instead, run the correct pressures, take the time to warm your tyres up and they’ll perform well.