I knew that my Kumho XS's didn't like the cold or the wet, but this past weekend, I learned that they are simply useless when it's cold and wet.

Here are the details;

This past saturday, my club (Gulfcoast Autocrossers) held our Test and Tune / Novice school day in the worst conditions I have seen in my 4 years of autocrossing. My Z's external temp display never went above 36 degrees, and it rained all day.

Our test and tune track stays the same from month to month so drivers know what mods (to the car and/or the driver) work and don't work.

My times have hovered around 31.0-31.2 for the past few months since I got my flywheel. (31.5-ish for a very long time before that)

This past weekend, (cold and wet) I was not as consistent as I am with my dry times but still only had about a one second spread between at leat 10 runs...My best was a 40.5

No grip.

In my Z, on the XS's, I was one of the slowest drivers of the day. At first I thought I simply wasn't able to drive well in the wet because, as far as I could tell, I had the biggest dry-wet time differential by a substantial margin. (among veteran drivers)

But one of the good drivers let me drive his C-6 Z-06 on run-flats and I got a 37.7 on my second run. (I only did two runs, his best time for the day was a 36.5)

On dry days, that Z06 is on race rubber and only about 1.5 seconds faster than my Z on XS's.

I have always known that my XS's need some heat to work well, and I have also known that they are not intended for use as rain tires. But this past weekend was a real eye opener for me.

I live in SW Florida so this weakness should not be an issue too often for me. But I thought I would share my experience with the rest of you who may compete in different conditions.

BTW, I ended up getting FTD....In a student's Bone-Stock Cooper Mini S, on brand new all-season tires. 36.1 backed up by two 36.2's.

 

At the National Tour "Deluge" in San Diego back in the late 90's I had FTD until late in the afternoon driving a HS Infinity G20 running on Michelin MXV4 tires. I was faster then ALL the Stock, Street Prepared, and Prepared cars until Rick Brown ran his BP Corvette on Hoosier Dirt Stockers.

At least 6 cars had their front spoilers ripped off when they went through "The Lake" down near the trolley overpass.

 

Thanks for the info. I also use XS here in Cali, and it can get very cold in the winter, but never as cold as your conditions. I'm sure that was out of the normal for you.

Tell me more about having a lighter flywheel. Did that really make your runs that much faster?

 

Well, they are an extreme summer tire...

 

In a word, yes. But our test and tune course has 2 spots where speed-maintenance isn't really an option. (and acceleration is king)

The benefit of the flywheel is kind of course dependent, but rev-matching is always easier, and I think the ability to stay in third more (than with the stock flywheel) seems to be helping my times too.

 

my clutch is starting to slip just a bit, so I'll be looking into getting a better flywheel when I upgrade the clutch. I'm guessing the stock flywheel is VERY heavy in this car.

 

I have a XS 285 for sale if u want it....