AutoX in the Rain
 

Doing my first autox coming up this weekend and it looks like it'll be in the rain. Running RE-11's 265/285 with -2.5 degrees of camber all around. Tips for tire PSI, how the tires will react in the rain, any general tips? Thanks. Thinking about keeping the spare in for added traction in the rear. Yay or nay?

Yes on the spare tire

Car will be as good as the driver, no different than any other car

Full tank of gas too! You will me most slowed down by your inability to put down power. Drive smooth.

Hmmm. Don't think this is a valid argument. While the ability to put down power is significantly reduced in the rain, it just tends to be an equalizer with cars of lesser power. More mass (gas and spare tire) would give more lateral force in corners reducing your cornering ability. Do better with only the gas you need and no spare while on course. Especially in the rain. But, definitely drive smooth.

Disagree. Lighter rear end with fat tires we have on 370Z (especially a summer tire like RE11) will hydroplane easier. You want the weight unless you can put a skinnier rain tire on the car. I have done plenty of wet AX's and had luxury of full day event where I ran to gas station to fill up and the traction benefit was noticeable.

I'd agree with you if surface was just moist but it there is any standing water you want weight in the rear. Also depends on course. If its a momentum course rear weight wont matter much but if you have many slow turns where you need to accelerate the car will benefit from added weight in the rear.

The only thing I would do is soften the suspension a bit. (if it's not too much trouble) In the wet, you will get less lateral g forces and thus less deflection on your tires' side walls. Lower pressure may be beneficial.

My 350Z on Kumho XS's in a lot of rain:


It felt like I was driving a shopping cart with those "spinny" wheels at all 4 corners. With water on course, the same input can give you wildly different results from one spot on the course to the next. Traction was "like a box of chocolates" and steering response was like a game of "Marco Polo".

I can't imagine any tire with tread on it being as bad as Kumho XS's in the wet, so I expect your RE11's won't be as bad.

Wrong.

By increasing the tire pressures, you reduce the contact patch and help reduce hydroplaning. Had a rain event last year, one run at the normal pressures I run and the next with 4 psi more all around. The higher pressure was noticeably better.

I said "may be beneficial" because conditions and tires and setups vary. I formed that view over countess wet events, and at least 6 different tire brands on the Z alone.

That being said, I don't recall running RE11's in the wet. I don't assume that all the dry runs I have had in different cars on those particular tires make me informed on the re11's wet behavior.

My advice is the result of what worked best on most of the tires, at most of the rain events I have driven in.

I run stretch H20's (275/35/17 on 17x11's)...it's disturbing how good they are. I watched John V (DSP BMW) out pace STR at Toledo last year (STR ran in the bone dry) in 4" of standing water on new H20's. Sadly for us first drivers, the rain hit as we were pulling into action. I don't change a thing on the car from wet to dry.

A6's were all kinds of fun at Toledo last year:
http://farm4.staticflickr.com/3774/9...f165dcf3_c.jpg

I'm not gonna argue with experience. I have only run in damp and that was years ago in a stock MGB. Not much problem geting power from it to the ground.

all my practice runs were on the very wet track. ran 36.5 psi front and 39 in the rear. also left traction control on and was easy with the throttle. i felt pretty fast but it was my first time doing auto x. felt slower with traction control off on the dry course later in the day.

Feel isn't the same as lap times

You were going too slow using traction control. Need to learn how to moderate throttle without the traction control crutch.