Up to this point, we have dealt exclusively with the dry line. When the track becomes wet, however, the dry lines is generally NOT the fastest way around the track. The reason for this is because when wet, the dry line generally has less grip than the off-line parts of the pavement.

Why does the Dry Line become so slick?
Since the dry line is the fastest line around a track, the cars driving on the track tend to drive that line. Over the course of months and years, the steady flow of cars over the same area polishes the pavement down and makes it smooth. When this area becomes wet, it becomes slick.

Additionally, cars are dirty, and deposit all sorts of nastiness on the ground. Bits of oil, rubber, and other nasty fluids all find their way onto the dry line just in the course of regular driving. When a car has an “issue,” and dumps gallons of fluids on the track, the problems compound. When it starts to rain, the water draws these fluids and oils out of the track, and they tend to float on the water. For this reason, the dry line is especially slick for the first few minutes of a rain shower, until the bulk of these oils and fluids get washed away. There still remains trace or significant amounts of fluid and nasties on the dry line even after heavy rain, so it remains slick.

What is the Rain Line?
In short, the Rain Line is the fastest way around a track in any sub-optimal conditions. Exactly what Rain Line is best depends first on the current conditions, and second on the setup of the car.

Driving in the rain is just a constant search for grip. As a general rule, you will be fastest if you drive on the grippiest part of a corner. But this rule is very fluid, so to speak. Just because there is a dry spot somewhere in a corner doesn’t mean that driving over it will automatically make you faster. You still need to be able to carve an arc of some sort through the corner. Playing connect-the-dots with dry or grippier spots won’t necessarily get you through the corner fastest.

Also bear in mind that because overall grip is lower, speeds will also be lower in the rain. This will change braking points and track out points even if the Dry Line is used. Start slow and build up.

Tires in the Rain
Tires lose more cornering grip than braking or accelerating grip in the wet. When wet, tires lose about 30% of their braking or accelerating grip, but 50% of their cornering grip. As a result, cars can carry much less speed through the corners in the wet, and rely more on power to keep their speed up on the straights.

Basically, you need to treat your car like an old American muscle car. Tip toe it around the corners as best as you can, then push it hard on the straights.

Where Can Grip be Found?
Once again, this depends heavily on the track and conditions in question. You could have two corners back-to-back, one of which has full grip on the line, and the other of which has zero grip on the line, but a ton of grip way on the outside of the corner. You need to experiment.

In a text-book 90 degree corner leading onto a straightaway, the Dry Line will be outside-inside-outside. Generally speaking, grip in the wet can be found in the middle to inside part of the track in the braking zone, the outside area opposite the apex, and inside of the track-out point.

Now lets look at a few different types of lines that you can take in the rain.

The Rim Shot
The Rim Shot is just as sounds: hugging the very outside of the corner. The logic behind the Rim Shot is that, as discussed above, there is a lot of grip to be found to the outside of the Dry Line, which is precisely where a Rim Shot will take you.

The Rim Shot is also a way to draw a fairly large arc through a corner. As you know from The Line, Part 1, hugging the inside edge of a corner draws the tightest possible arc through a corner, and the Dry Line draws the largest arc possible. The Rim Shot falls somewhere between an inside line and the Dry Line. It is wide enough that the extra grip afforded by going off-line (off of the Dry Line) allows you to take the tighter arc of the Rim Shot faster compared to the speed you could maintain on the less grippy but wider arc of the Dry Line.

Lime Rock is an excellent example of where to use the Rim Shot. Under wet conditions, the fastest way around Lime Rock is hugging the outside of each corner, in a classic, textbook-style Rim Shot.

A Modified Rim Shot
The problem with the Rim Shot is that by staying wide throughout the entirety of the corner, you must travel on the Dry Line during the braking zone and track out points. As we know, the Dry Line is very slippery when wet, which means that you are braking and accelerating on some of the slipperiest parts of the track.

The way around this dilemma is to modify the Rim Shot to avoid the slick braking and track out zones. You therefore want to move your braking and accelerating zones to the inside of the corner, just off of the Dry Line.

The tricky part is then connecting these two new zones. Because the Dry Line always hugs the Apex tight, you will, out of necessity, have to cross the Dry Line twice for any Rain Line. Since the Dry Line is so slippery, you want to be going straight NOT turning when you cross the Dry Line. This means that all of your turning should be done in the grippy outside part of the corner, across from the Apex.

So, putting it all together, A Modified Rim Shot would go something like this (lets imagine a text-book style 90 degree right hand corner): your braking zone has been moved to the middle or right side of the track, and all or most of your braking is done before you reach the Dry Line. You cross the Dry Line, backing off of the brakes slightly to prevent them from locking up due to the decreased traction. You begin turning on the grippy area outside of the Dry Line, finishing all of your turning in the outside area of the corner, across from the apex. You straighten the car before hitting the Dry Line for a second time, aiming for the middle or right side of the track. You accelerate but breath off the throttle slightly as you cross the Dry Line to prevent wheel Spin, then roll back on the throttle once you have passed the Dry Line.

The only downside to this approach is that you have now created a very tight turning radius in the area outside of the Dry Line. To be successful, this technique requires enough extra grip in this outside area to take you faster on a tigher arc than you could hold on a larger, slippier arc. It is not automatically the best way through a wet corner, and its efficacy changes with the conditions and the design and structure of the actual corner itself.

Concrete Patches
Many tracks have strips of concrete patches strewn about the track. These are ways to fix problem areas of the track without having to completely repave a section or the entirety of a track. In the dry, you shouldn’t pay too much heed to concrete patches, as the traction difference, in general, between them and the surrounding track is negligible. The difference is almost never enough to warrant a modified line. If anything, they give good on-track reference points for the Dry Line.

In the wet, concrete patches are a nightmare. They are, generally speaking, very slick compared to the surrounding pavement. On top of that, they are often placed right on the line.

This is not always the case, however. Once, in one of my classroom sections, someone reported driving on concrete that was very rough, and, consequently, afforded lots of grip, even more than the surrounding pavement in the wet. You need to experiment with the track you are on and see how the concrete behaves in different conditions.

Be mindful of concrete patches, as they often require slight or major modifications of the Line in the rain. A good technique is to place the outer two tires just off of the concrete patch, where grip is usually much higher. Since these two tires are doing most of the cornering work, cornering ability should increase greatly. If riding slightly wide over the patch is not an option (e.g., the patch is right against the edge of the track), modify your line to accomplish more turning elsewhere in the corner so that you can be going straighter over the concrete patch.

If all else fails, simply take that corner more slowly. You will be faster around the track if you DON’T spin-out on a wet concrete patch.

New Pavement
New pavement is a toss-up. It can either have more or less grip than the pavement it replaced, and this can change significantly as other racers wear The Line into the new material. The materials used to make the new pavement can also make generalizations difficult. Some are rougher or smoother than others, and this will also affect grip.

For very new pavement, it is probably safe to say that you The Line will still have a good amount of grip in the wet. The surface will not have been polished quite so smooth yet, and the amount of oils and other nasties on the track won’t have had that long to build up.

But, it could have been a long time since the last rain, and these nasties may indeed have accumulated significantly. Or someone may have decided to dump all his engine oil right on The Line. New pavement is a toss-up. Take it slow, see where the best grip is, and modify your line accordingly.

Standing Water
Tracks are built for viciousness in the dry, and don’t always take into account what happens when it rains. Some tracks may flood in certain areas. These areas obviously should be avoided, so modify your Line accordingly.

Some areas may have streams of water traveling across the track. You will likely hydroplane over these streams, so plan accordingly. Make sure the wheel is straight and you are not heavy on the brake or throttle. Be particularly mindful of such streams in corners, as that wall at track out will not be very mindful of you.

Changing Conditions, Changing Lines
The Rain Line is the fastest Line around the track for the current conditions. When the conditions change, so does the Rain Line.

The easiest conditions to drive in are those that are consistent. The Dry Line is, in the grand scheme of things, simple and straightforward. You figure out what works best, and then you drive that same line over and over and over again, striving for consistency. In the wet, the easiest condition to drive in is likewise when the track is consistent. A steady shower that uniformly coats the track for your entire session is easier to drive in then a session that starts dry and turns wet, or starts wet and dries out. The first scenario requires one Line, with minimal tweaking. With the second scenario, you could have a different Line each lap for your entire session.

The track will dry differently in different places, both from corner to corner, and within the corner itself. For corners with concrete patches, there is yet another element to contend with, as they will dry at differing rates as well.

One thing to keep in mind is that the line most heavily driven will dry first. You now how as a highway dries, the outside of a lane dries first? That is because this part of the lane is dried out by countless tires driving over it. The same phenomenon applies on the track. If everyone is driving on the Dry Line in the wet, it will probably dry before the rest of the track. Probably, but not necessarily. It is just something to keep in mind as conditions change.

In changing conditions, the best way to change your line is to experiment each lap. Try moving to a drier, grippier section of the track, and see if your exit speed improves. As you log more hours in wet conditions at your local tracks, you will become more familiar with how each corner fares as conditions change. This will give you a good baseline to work from, but you will still need to gauge the conditions for each lap.

Car Settings and the Rain
The number one factor in the rain are your TIRES. The importance of tires for wet weather traction CANNOT be overstated. Tires that work well in the dry do not necessarily work well in the wet. In fact, the best dry-weather tires, slicks, are the worst tires in the wet. In the rain, tires rely on tread design to move water out of the way of the rubber, so that the rubber can contact and grip the pavement. Slicks have no tread, and thus nowhere for the water to go. You are literally driving on water with slicks, and water doesn’t have nearly as much grip as pavement.

There are a variety of rain tires on the market, from full R-compound rain tires to maximum performance street tires. I have had good success in the wet with Goodyear Eagle F1 GS-D3s, though there are other good options as well. If you plan to do a significant amount of driving in the wet, it pays to get a good set of rain tires.

Other car setup issues revolve around tires and traction. The next biggest thing to do is to soften your suspension. Many aftermarket shocks have adjustable dampening, and the wet is a good time to use them. If you have adjustable sway bars, consider softening them as well. The benefit of a softer setup is twofold. First, it softens and slows transitions and weight transfer. This allows more time for the tires to become loaded and unloaded, and your are much less likely to upset the balance of the car and break a tire free when cornering. It will also take longer for weight to transfer when braking or accelerating, so make sure to ease on and off of the brake and throttle, so as not to lock up the front wheels or spin up the rear wheels.

The second benefit of softening the suspension is that it allows the car to roll as much as it would in the dry, making full use of more aggressive, dry-weather camber settings. Camber settings of 2-4 degrees, or more, are common on track-oriented cars. These settings assume a certain cornering load, which makes the car roll onto the tire fully. In the wet, cornering speeds will be less, and cornering loads will therefore also be less. Without softening the suspension to allow for increased body roll at lower cornering loads, the car will never become firmly planted on its tires in a corner, and it will effectively be like driving on a narrower tire (i.e., less grip).

If you want to go a step further, you could reduce your camber settings specifically for driving in the rain. However, unless you have a dedicated rain car, you will have more fun in the dry and be far more versatile choosing dry-weather alignment settings softening the suspension. The dry line is predictable, and settings can be better selected. Rain driving changes so often that it will be impossible to have a single setting that best covers all conditions. The best you can do is set your alignment for the dry, and tune your suspension by softening your shocks and sway bars.

Visibility
In many ways, visibility is the most important part of driving in the rain. After all, you can’t control your car or follow any line if you can’t see where you are going.

Make sure your wipers and wiper blades are in good working order. I find wiping my blades down with some dishwashing soap occasionally does wonders to reduce streaking. Eventually, however, wiper blades do wear out. The rubber becomes hard and brittle, and may break away from the rest of the wiper blade. You’ve probably spent countless thousands of dollars on your car and modifying it, plus several hundred dollar just to be able to drive it on a track for a few hours. Don’t short-change yourself by not spending $30 on new wiper blades.

An amazing product that I swear by is Rain-X. It forms a layer on glass that water can’t bond to. The water simply beads up and the wind pushes it off of the windshield. I drove a friend’s beater car for a little while when my car was in the shop once. It had terrible windshield wipers, to the point that Rain-X without using the wipers produced better visibility than actually using the wipers. It is amazing stuff. Rain-X will wear off over time. I usually apply a fresh coat just before a track day.

Finding the Rain Line
Until you have a good understanding of the Dry Line, it is best NOT to start looking for the rain line. Finding the Dry Line is difficult enough, even under optimal, uniform conditions. Until you understand the Dry Line, it will be futile to try and avoid it to find grip elsewhere on the track.

If this article has sounded wishy-washy, it’s because that is precisely what the Rain Line is, on multiple levels. It is constantly changing with conditions and car setup. START SLOW and SMOOTH, find where the grip is, modify your line accordingly, and speed will naturally follow.