Racing In The Rain - Art Of Racing In The Rain

With apologies to Garth Stein and his excellent novel by the same name, the art to racing in the rain isn't just an inherent skill that some drivers have and others do not. The truth is that learning to race in the rain - we're talking driving your car as fast as possible around a wet racing circuit - is part feel (or art, if you prefer) and part science. The feel part is something you have to develop from practice, practice and more practice. The science part, on the other hand, is something you can investigate intellectually, learn on paper and then go about applying in the real world. But to apply the science of racing in the rain skillfully and artfully, you've got to find yourself on a wet racetrack, which goes back to that whole practice, practice, practice thing.

A lot of racers in the United States, especially those of us who live in the dry southwestern part of the country, regard racing in the rain as something that should be avoided. I've seen some very reputable West Coast racing teams opt to park their car rather than risk a big off-track excursion in the rain. But in the Northeast, Northwest and throughout the UK and Europe, racing in the rain isn't only seen as a required part of a racer's skill set, it's often relished by drivers and seen as a way of separating the men from the boys. Racing in the rain is also an excellent way to develop smooth and precise inputs with the steering wheel, brakes and throttle because the repercussions of upsetting the car's tenuous grip are greatly magnified on a wet surface. The funny thing is, the smooth and precise driving technique required in the rain just so happens to translate to faster laps in the dry too, since the same principles of conservation of momentum and minimizing weight transfer apply just as much in the dry as they do in the rain.

A good place to start when thinking about how to go fast in the rain is to consider the one part of the car that's actually in contact with the wet tarmac: the tires. Before you even consider whether or not you're on a slick or semi-slick with little to no tread depth and ability to evacuate water from its contact patch, it's vital to realize that even the best rain tire reacts differently during use on a wet surface than it does on a dry surface.

When you graph slip angle against traction for a tire in the dry and a tire in the rain, it's easy to see that traction is less progressive when it's wet, meaning it reaches its limit quicker and lets go quicker.
When you graph slip angle against traction for a tire in the dry and a tire in the rain, i
The traditional racing line is fastest in the dry, but when the track is wet it's best to straighten out the track and stay off the dry line in the turns.
The traditional racing line is fastest in the dry, but when the track is wet it's best to

A tire in the dry is able to build considerably more traction, and as it reaches its peak, the available traction levels off for some time before gradually falling off as you overdrive the tire and create excessive slip angle (experienced as understeer, oversteer or a four-wheel drift, depending on which tires lose traction). Since traction loss is fairly gradual in the dry, it means you'll be able to feel it happening soon enough to counteract the slip by reducing velocity and/or changing trajectory; in other words, you can catch the skid by braking a bit, easing off the gas and/or countersteering, depending on what the particular scenario calls for.

In the rain, however, a tire will reach its traction peak much earlier than in the dry and it will also level off more quickly and drop off more suddenly as slip angle increases. This means less time to react to a loss of traction, and if you don't react quickly enough things can go from bad to worse in a hurry. Whether you're conscious of it or not, you're probably using a slip angle of 6 to 10 degrees in the dry (generally considered ideal in terms of generating maximum grip from the tires), but in the wet the optimal slip angle is more in the range of 3 to 6 degrees. Understanding how your tires operate in the rain is the first step to maximizing speed while averting an unscheduled trip across the infield, but there are lots of other factors that will also help you find the fastest way around a wet circuit.

FWD tends to work well in the rain because of the engine's weight being over the drive wheels. AWD works even better.
FWD tends to work well in the rain because of the engine's weight being over the drive whe
Your tires and brakes work surprisingly well in the wet, but don't be fooled into thinking you'll have the same amount of grip while cornering or accelerating.
Your tires and brakes work surprisingly well in the wet, but don't be fooled into thinking
Spray from the cars ahead can make visibility a huge problem. For HPDE or time attack, be smart and leave a gap so you can see where you're going.
Spray from the cars ahead can make visibility a huge problem. For HPDE or time attack, be