The Art and Science of Racing in the Rain 

By Dave Pratte 

Hidey ho my fellow MotoIQ readers. My name is Dave Pratte and you may know me from such Driver's Ed films as "Alice's Adventures through the Windshield Glass" and "The Decapitation of Larry Leadfoot". No wait, that's Troy McClure. My bad. Lets try this again. You may know me from Modified magazine, where I used to be the Senior Editor and where I still write a monthly Tech column (ingeniously called 'Tech Talk') and contribute all sorts of other content on a regular basis (I've also contributed to Super Street, Grassroots Motorsports, Modified Luxury & Exotics, Modified Mustangs, S3, AutoGuide.com and Hairy Bears Quarterly...ok, maybe not that last one). But unlike most magazine editors, I didn't get into this business for the free tires or cool press events. I fell into it because I'm a racer and the magazine happened to be looking for someone who could provide them with the type of insights that only come from breaking parts and the occasional track record. 

Dave Pratte Dave Pratte; Honda Civic; Canadian Touring Car Championship
Hello MotoIQ. My name is Dave Pratte and racing is serious business... Chasing this STI down in my K24-powered EG Civic during a damp Canadian Touring Car Championship race was some of the best fun I've ever had behind the wheel. As you can see from the body roll, the relatively soft setup I was using paid big dividends once the wet stuff started to fall, but more on that later. 

Of all the stories I've cranked out during a decade or so of work in this industry, the one that generated the most reader feedback was called "The Art of Racing in the Rain". No, this wasn't a review of Garth Stein's novel by the same name, but rather a look at how to go fast in wet conditions. Some of the e-mails I received about this story included funny tales about driving (and crashing) in the rain, while others wanted to talk about the similarities between wet conditions and snowy or icy conditions. Whatever the case may be, this story seemed to strike a cord with a lot of go-fast enthusiasts, so I thought it would be appropriate to share it here but with some additional technical insights, since MotoIQ is all about understanding how to go fast in an intelligent way. 

Contrary to popular belief, the ability to go fast (without crashing) 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 race track, which goes back to that whole practice, practice, practice thing. 

There's no substitute for seat time when learning the art (and science) of racing in the rain, but hopefully you'll do it in something a little more forgiving than ASM's S2000, which looked like it was trying to kill its driver during a rain-soaked GT Live Time Attack event at VIR back in 2006.



wet skid pad
A great way to develop a feel for your car's attitude at the limit of available grip in the wet is to find an empty parking lot on a rainy day. 


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Tuesday, April 17, 2012 10:09 AM
This article definitely inspired more confidence in me for wet track days.

Could you please shed more light as to why you'd want to induce rear rotation by use of trail braking? I'm trying to picture it in my head as well as connect the dots to the other points you've made.
Tuesday, April 17, 2012 10:40 AM
I see we have some fans of Ross Bently in the house. :)
Der Bruce
Der Brucelink
Tuesday, April 17, 2012 10:54 AM
Whoa! What a great addition you are Dave. We now have three former/current tech contributors on Motoiq, amazing!

Having lived in the Northwest most of my life, I'd also add/second that FWD which naturally understeer and RWD that oversteer do it MUCH worse at the limit. Hence, know your limits!
Dave Pratte
Dave Prattelink
Tuesday, April 17, 2012 11:26 AM
jexeffectz, trail braking is a technique that helps combat understeer or induce a little oversteer, thereby getting the car pointing in the direction you want a little quicker than you'd be able to otherwise. It's typically used in FWD or AWD cars that have too much front push or understeer in them. This means braking while turning in to the corner and then trailing off the brakes as you approach the apex and transition onto the throttle. Advanced drivers will sometimes left foot trail brake so that they can also be on the gas -- you'll often see this type of two-footed driving amongst rally drivers, since they use the brakes a lot to change the attitude/direction of the car as much as to slow it.

isocuda, you caught me! I did indeed pull a few of those graphs from Ross Bentley's excellent book 'Speed Secrets'. I should really edit the captions to give him credit.

Der Bruce, thanks for the kind words.
Dave Pratte
Dave Prattelink
Tuesday, April 17, 2012 11:38 AM
BTW jexeffectz, I should also add that the way trailing braking works is that by carrying your braking into the corner you keep more weight transferred onto the front tires, giving them more grip and at the same time transferring weight off of the rear tires and thus giving them less grip. The aim here is to allow the rear tires to achieve greater slip angle and go past their traction peak. This lets the rear tires slide and the car to rotate. This lets you complete the turning process sooner and get back onto the gas sooner, plus it often lets you carry more speed into the corner too. It's something you have to experiment with to get good at, but it can be a very effective technique if your car naturally wants to push or understeer when cornering.
Tuesday, April 17, 2012 12:03 PM
Thanks for further input Dave. I understand the idea of how it works now.
Dusty Duster
Dusty Dusterlink
Tuesday, April 17, 2012 12:43 PM
Any words of advice for driving high-power, high-torque, RWD cars in the wet?
Tuesday, April 17, 2012 1:59 PM
@ Dusty Duster: Yeah, don't use the high-power, high-torque. ;-p
Dave Pratte
Dave Prattelink
Tuesday, April 17, 2012 4:14 PM
Hah, yeah I'm with Rockwood. WIth a car like yours (I'm assuming Mustang 5.0) you really need to emphasize slow smooth inputs with the wheel, brakes and especially the throttle. Patience is a virtue in the rain and that's doubly true in a car like yours since you need to feed the gas in with extra discipline to avoid acceleration-killing wheel spin. You also need to factor in the mass of your car, which is going to demand longer braking zones.
Tuesday, April 17, 2012 6:20 PM
Dave speaks truth! I remember the exact instant where I learned to drive in the rain. It was 3am at the 2008 NASA 25 Hours of Thunderhill. It started raining at the beginning of my stint, and I tackled it like any other CA driver would: I slowed down! About an hour later, I was getting frustrated getting stuck behind slower traffic that I couldn't figure out how to get around, when I recalled other learned drivers would had been trying to bestow this wisdom on me. Being from CA, I had never had the chance to really put these things to much practice.

Well, this seemed like as good a time as any! So I literally started to drive around in the middle of the track everywhere, line be damned! And before you know it I had dropped like 5 seconds a lap and was passing people like nobodies business. What amazed me the most was that my braking zone were THE SAME as in the dry, and one(Turn 6) was even deeper than in the dry, a combination of reduced overall speed, and the effect Dave is talking about(that longitudinal traction doesn't fall off as bad). This went double if braked off line, which as you know is quite good for passing!

So I drove like this for the remaining 2.5 hours, making for a 3.5 hour rain stint, the longest in my life. near the end I had a great battle for position with one of the MAZDASPEED MX-5s, and eventually passed him at turn 6 by doing as Dave says: drive in deep, short little turn, drive straight out so I could use full throttle. I pulled straight away from him as his little miata danced around trying to get traction at exit, I was rocking away(didn't even track out, didn't need to, I had my grip). My crew chief calls me and says "you are the fastest car on track in our class right now, and you just passed Eric Curran for position!"

Ever since, I like the wet. CA boys, NEVER let rain keep you in the paddock.

Great article Dave.
Dave Pratte
Dave Prattelink
Wednesday, April 18, 2012 5:02 AM
Thanks Chris, that's a great story and really brings to life the excitement and unique challenge that racing in the rain offers.
Gary Sheehan
Gary Sheehanlink
Wednesday, April 18, 2012 10:00 AM
To bastardize a great line from the Matrix:

Kid: Do not try and drive the dry line in the wet. That's impossible. Instead... only try to realize the truth.
Neo: What truth?
Kid: There is no line.
Neo: There is no line?
Kid: Then you'll see, that it is not the line that drives the car, it is only yourself.

This is the way I approach driving in the rain. I go exploring. I drive different lines in each corner and find the areas that provide the most grip that sacrifice the least amount of corner-speed. There's almost always a trade-off between grippy track and corner-radius. The grippiest part of the track in the rain may not be the fastest way through the corner. So I explore and figure out what works best on that track, in that car, on that given day.

Here's an in-car video of that 600hp Subaru at Infineon in the photos above. Crappy old tires that were raced hard in the dry, and a peaky powerband makes the time spent on the dry line exciting - http://www.youtube.com/watch?v=xm2CxPj6qDI

Here's another video driving in the rain at Thunderhill with much better tires and relatively tame power delivery - http://www.youtube.com/watch?v=K8o2R5tEL24

I still remember the day I made the transition from hating driving in the rain to loving it. After a mostly sleepless night before an event, with the rain bucketing down, I
came to the conclusion that if I wanted to do this race driving stuff, I was going to encounter a lot more rainy days. So I decided to start enjoying it rather than dreading it. Now I look forward to driving in the rain at every opportunity.

The power of positive thinking at work :)

Thanks for the mention, Dave!

Gary Sheehan
Dave Pratte
Dave Prattelink
Wednesday, April 18, 2012 10:18 AM
Wednesday, April 18, 2012 9:27 PM
Dave it's a shame you're no longer writing for Hairy Bears Quarterly. I really enjoyed your insightful article on determining whether you're a Top or Bottom.

In all seriousness though, great article on wet driving. Driving at the limit in the wet really is a different animal than driving at the limit in the dry and this article makes that abundantly clear.

P.S. If anyone seeing this hasn't read "The Art of Racing in the Rain" I highly recommend it. Great fictional dog story/life story.
Thursday, April 19, 2012 9:54 AM
Don't forget Ayrton Senna... Another master in the rain. Just go to youtube and do a quick search. It is worth it.

Great article Dave! :)

I love racing in the rain... But driving on a wet public road is another story all together. I guess one can't compare but I would say that driving on road is more dangerous. From winter to winter I keep risking less and less (and I remember it being funny some 15 years back). Probably due to wider tires with stiffer walls and stiffer suspensions than back in those days...
Dave Pratte
Dave Prattelink
Thursday, April 19, 2012 10:00 AM
Fly'n_Z: Go Enzo!

VP: That's actually a great point about modern day cars having stiffer/shorter sidewalls and suspensions than they used to and how this tends to make them less forgiving in the rain. This also raises the air pressure issue, and if less is more in the rain. On the upside lower psi will give you a softer sidewall and those a more forgiving setup in the rain, but on the downside the tire will build temp faster with more psi. So it's a bit of a double-edged sword here, but in my experience if it's really wet on track it's worth dropping tire pressure for the added sidewall flex.
Sunday, May 06, 2012 5:24 PM
dave, can you get with me about coming on the radio show?
Dave Pratte
Dave Prattelink
Sunday, May 06, 2012 5:29 PM
Sure Will, sounds like fun to me! Do you want to shoot me an e-mail at planetdave "at" me "dot" com?
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