Cal Club Autocross Forums

I checked weather.com's 10 day report for Fontana and its almost guaranteed to rain. Is it worth it to come out to the event if it rains or is it a drag?

Racing in the wet is the BEST!

It's fun!

It will help your driving skills in the rain.

I can't wait to race in the rain

Grown up version of jumping into puddles like you did as a kid!

lol guess i will show up then regardless of weather conditions. i'll just bring a couple extra pairs of shoes/socks, some dry clothes, and of course an umbrella. do different tire pressures come into play with the rain?

According to Rain Specialist Annie Bauer ... Seattle ... a bit less pressure. Basically keep everything soft, including your inputs.

We have some people who insist on banning umbrellas on course. You never know one event to the next who will be in charge, so be prepared for life without on course.
For Topeka, I got a nice rain jacket from Cabelas for like $30 shipped and it was a godsend in the deluge.

Mako Koiwai wrote:According to Rain Specialist Annie Bauer ... Seattle ... a bit less pressure. Basically keep everything soft, including your inputs.

it sucks that Annie's wrong.

generally 2-4 more psi in the rain, YMMV.

Theory being???

First thought is increase compliance in rain. Softer everything.
Although on Civies, I found softening rear bar to induce MASSIVE inside wheelspin in the ProFinale.

Mako Koiwai wrote: Basically keep everything soft, including your inputs.

Hehe. Soft inputs...

Steve Ekstrand wrote:Theory being???

First thought is increase compliance in rain. Softer everything.
Although on Civies, I found softening rear bar to induce MASSIVE inside wheelspin in the ProFinale.

Keep the tread open to shed water.

Steve Ekstrand wrote:Theory being???

First thought is increase compliance in rain. Softer everything.
Although on Civies, I found softening rear bar to induce MASSIVE inside wheelspin in the ProFinale.

Tire Rack says,
"TIRE PRESSURES IN THE RAIN

For both autocross and road racing, increase tire pressures 6-10 psi from what you would normally run in dry conditions. Hydroplaning occurs when a wedge of water develops between the tire and road surface. This wedge can actually lift the tire off the road and eliminate traction. Increasing the pressure rounds the profile of the tire by decreasing the deflection of the tire. This results in a smaller contact patch - narrower and shorter. It also helps keep the grooves in the tread open so they can channel the water out from under the tire."

http://www.tirerack.com/tires/tiretech/ ... ?techid=58" onclick="window.open(this.href);return false;

Steve Ekstrand wrote:Theory being???

First thought is increase compliance in rain. Softer everything.
Although on Civies, I found softening rear bar to induce MASSIVE inside wheelspin in the ProFinale.

Theory being that you need increased pressure to reduce the surface area presented to the water and thus increase the resistance to hydroplaning. also there is a small increase due to the higher pressure shortening up the length of the contact patch and thus reducing the length of sipes the water has to travel through to be evacuated from under the tire thus increasing the tires ability to pump water out from under it.

Suspension changes are going to vary too much to make any general statements. The only constant is that you're going to have lower peak accelerations.

Marshall vs Annie Bauer ... now who actually has a LOT of rain racing experience! ;) Annie says half of their events are in the wet.

Yeah ... there is always that debate. In standing water, super low pressures so that the middle of the tire actually folds up a bit ... OR, lots of pressure in order to crown the middle of the tire so it cuts through standing water better ?!?

In non-standing water, wet conditions, soft but slick R tire compounds or ST tires that get excellent wet reviews?

In my very first AX I almost won SM with my almost stock WRX, not only because I had AWD, but I had Toyo T1S's that were just amazing in the wet. Most everyone else had R's. The newer R1S isn't as good, but the Goodyear GS-D3 IS.

I've always wondered how that tire would compare in very wet conditions to say the new Dunlop Star Spec Z-1 Maximum Summer tire that gets very good wet reviews.

I think there are a lot of variables, vis a vis tire pressures, how wet, how much standing water, which tires, how wide, side wall complaience, etc.

Of course in snow and ice one wants a thinner tire for more pressure. It's strange to see the WRC cars in the snow rally's with wide body work and those incredible thin studded tires.

Mako Koiwai wrote:Marshall vs Annie Bauer ... now who actually has a LOT of rain racing experience! ;) Annie says half of their events are in the wet.

We also have this guy Yeoh that might be able to help answer too!!!

Yeoh!!where are you...

Mako Koiwai wrote:
Of course in snow and ice one wants a thinner tire for more pressure.

Not more pressure; more directional stability.

With studs and ice ... more pressure.

Same with skiing, when you're racing on ice, you can only be on your edges. If you're on a flat ski, you will be sliding all over the place. It's very cool to be able to ski on real ice, just going from steel edge to edge. Being on edge of COURSE gives more directional stability ... also.

Mako Koiwai wrote: Yeah ... there is always that debate. In standing water, super low pressures so that the middle of the tire actually folds up a bit ... OR, lots of pressure in order to crown the middle of the tire so it cuts through standing water better ?!?

Really there isn't when you read the papers on it. No debate, raise the pressures. At the grass roots level there is debate because people think what they feel or what they think "common sense" is trumps decades of data by top race teams, that or someone on a forum told them once.

I don't see dropping pressure to fold in tire. That would trap water whereas crowning the tire with pressure would push water out on each side.

I would think... Scary as that is.... That you'd run lower pressures in damp conditions and higher pressures in standing water.

What if your tires don't enough tread to evacuate water? ;)

Sebastian Rios wrote:What if your tires don't enough tread to evacuate water? ;)

Then you're on the wrong tire for the conditions and you're screwed. haha.

You mean like when I ran the ProFinale on shaved tires???

Steve Ekstrand wrote:I don't see dropping pressure to fold in tire. That would trap water whereas crowning the tire with pressure would push water out on each side.

I would think... Scary as that is.... That you'd run lower pressures in damp conditions and higher pressures in standing water.

In damp conditions I say don't screw with your car and drive around the dampness. You're far more likely to guess wrong and screw up the balance then to actually be able to fix anything.

even so, lower pressures makes your tires run cooler. So in damp conditions you have no desire to decrease tire temps so I would run higher pressures to get as much heat in the tire as possible.