Phokaioglaukos

Looks like I'll be driving on a wet track at the Glen this weekend. Toyo says that the RA1s like to be run in the high 30s/low 40s PSI hot and 160º-220º F.

How do I do that on a wet track? Do I lower the pressure so that that I get to that range of hot pressures/temps, but how low can I lower the pressure? There must be some diminishing returns.

I'd appreciate your advice.

Dbltime

If your target is 40# hot start at 30F/32R# on a dry track
semi wet but no standing water, line dry in areas maybe add 1-2#
steady to heavy ran I would start at 36/38

this would be a reasonable base line and keep records, adjust as needed

Don't forget the rainX

Mike Buck

I hope your Toyo's are either scuffed or shaved. Brand new full tread tires will be almost undrivable until the mold release is 'burned' away

Phokaioglaukos

Thanks, Bill. I guess I'll look for pressures and not mess with the pyrometer, at first.

Mike, the tires are not shaved and have two track days, so they are well scuffed.

earlyapex

Have fun Chris. I used full tread RA-1's for 3 very wet events at Laguna Seca early this year. They are a great rain tire. Don't forget to find the "wet line".

Phokaioglaukos

I drove Laguna Seca for three days with the Skip Barber school. One day dry, one day monsoon, and the third day dry. The wet line there was anyplace other than the dry line, and it was like being on ice when I had to cross the dry line! I have no idea of the wet line at WGI....

Larry Herman

The best wet line there is to stay in the garage!

Seriously, I found that the Glen was pretty good in the wet. You can either take an outside line (better for cornering), or just try staying right in the middle of the track (better for braking and accelerating). Either way make sure that you have no real cornering loads when you get to the places where you have to cross the dry line.

renvagn

Interesting about the wet tire temps, but I have heard you want to run a higher inflation. I would guess this would decrease the contact patch and hydroplaining. Can anyone shed some light????

chrisp

Since the water has a cooling effect you start with a higher cold pressure. There's not as much pressure build in the wet so, for example, you normally start at 32 psi cold and get up to 40 psi hot then in the wet you may need 34 psi cold to get to the same 40 psi hot (actually more like "warm" when it's wet).

Jarez Mifkin

I think running the higher pressures in the rain help to open up the tread a bit to help with water dissapation.

Dbltime

GOING FASTER has a very good chapter on track driving in the wet. Ultra smooth on the shifts, brakes and throttle application, soften up your suspension and read the racing surface. Don't cross streams of running water with steering input. Stay off painted curbs. Water is a lubricant. Consider tread pattern (depth/directional) vs amount of water and practice until you feel comfortable sliding the car around in control. Sounds easy to me ;->

chrisp

If both set-ups end up leveling off at the same pressure then the contact patch is the same.

To ovalize the contact patch and flow more water you would need to add a few pounds to account for the cooling effect and a few pounds to get over the standard hot pressure that you're proposing doesn't flow water as well. This would mean a 4-6 psi increase wet over dry.