Originally Posted by ChrisDP
On wet pavement, I've found it's better to lower tire pressures to get more footprint. I've tried this autocrossing, I was MUCH faster on wet pavement with low pressures. Through standing water, I find higher pressures channel water away better. If there are lakes forming near a large immovable object... I'd probably try and optimize my car's handling for that area.
For the record, differnt tires like different tire pressures in the rain. With some tires, you want to increase the tire pressure, with some you want to decrease the tire pressure. There is no way to say that one way is universally better than the other.
The Toyo RA-1's usually like 2-4 PSI more cold tire pressure than what you would run in the dry. Most (NOTE: NOT ALL) street tires like 3-4 PSI less than what you would run in the dry.
If the RA-1's have more than about 4/32nds of tread on them, unless you are driving through puddles, they will be faster than street tires.
Other hints: Get ALL of your braking done in a straight line. Usually squaring off the corner and getting the car pointed straight sooner allows for better acceleration and quicker overall lap times even though this may mean a slightly slower minimum corner speed.
Going fast in the rain means going where there is grip on the track. If the track is evenly wet, usually 1-2 car widths off line has the most grip. This also usually holds true if it has just started raining. On a drying track, the most grip is usually where it is the driest, regardless of where that happens to be. This can lead to some very unusual lines.
STAY OFF THE CURBS!!! Also, try to avoid the painted lines on the pavement. Wet paint = zero grip.
As a note on my on track rain driving experience, I was really hoping for rain for my race at the SCCA Runoffs this year. My best race was at NHIS in wet to drying conditions (4th/8), and my best session this year was at Nelson Ledges. The first session was wet, and it was the first time I had ever run there in the rain before. I was 2nd/6, with 3 of the other 5 finishing in the top 10 at the SCCA Runoffs this year. With an SCCA SSB legal Miata, at a Time Trial this October at NHIS in the wet, I not only won the class I was in by 4 seconds/lap, I had the fastest overall Miata, the fastest showroom stock prep car, which included an instructor in an STi, and there were only 2 subarus out of about 10 that were faster than I was, 1 STi and one 300+ WHP heavily modded WRX.