AX racing on street tires - loud is good?, pushin the limits and lookin for more Options

[Chris Pincetich]

I gotta stick to the tires I have now for 2007 due to AX class points and my budget.

I have 195/50 Dunlop 2000 Sport (I think) on 15x6" alloy rims. I got these because I was worried about fitment of 205s and never guessed I'd becaome an AX addict. (IMG:style_emoticons/default/happy11.gif)

These tires seem to get more slippery as they warm up. As a result, I end up fish taling a bit. I tend to 180 slide about once a day, and can keep the back end from swingin around 90% of the time. Some times I mash the brakes, turn in fast, get about 10-20 deg fish tail, and hook up heading right for the next apex. YEAH it feels great and I hear the tires squeel. Other times I have a smoother approach and lots of squeel all through the arc of the turn. Sometimes I'm smooth and don't hear the sqeel. With so many turns adding up to my time, it is tough to tell which approach is fastest. I don't feel like I kill any speed on my little slip slide and hook up and when I watch others it looks fast as long as the tail isn't swingin out wide.

My AX book (with the 911 on the cover) talks about the friction circle, and I think I need more info here. It says that pushing the limit up to the grip release is fastest, and then hints that sometimes going a little outside the cirlce is fastest. Losts of allusions to pushing the limits but no "one size fits all" explanation.

Is this loud sqeelin approach as good and fast as it feels, or am I just enjoying the ride and going slower than I could?
At what point in the friction circle are my street tires making the squeel noise?
Is the soft compounds in DOT-R and slicks too soft to resonante and make the squeel noise? (IMG:style_emoticons/default/idea.gif)

I started dropping PSI this year - from 32-34 down to 24-26 PSI at the last race. Still well on the tread, not rollin over to the tread wear line. Is this extra side wall flex good? I think so!! (IMG:style_emoticons/default/w00t.gif)

I know most of youz guyz had humble beginnins like me and my rustored 1.7 914 so enlighten me on the finer points of maxing out my street tires! (IMG:style_emoticons/default/beerchug.gif)

[Dave_Darling]

My perspective, others may have different opinions (in which case they're wrong! (IMG:style_emoticons/default/lol2.gif) ) --

Smooth is good.

Most street tires tend to make noise when they get somewhere near the limits of adhesion.

--From those two, I think that your #2 approach (smooth with tires squealing the whole way through) is the better one. Wagging the tail is almost (almost!!) never the fastest way through the turn. {note the edit; added the word "never"}

Smooth also includes unwinding the wheel while you are applying the gas. Hopefully before the apex of the turn (though that can change with some turns).

I have found that most street tires seem to grip better with more air pressure. My guess is that the gains from stiffening the sidewall were larger than the losses from making the contact patch smaller, but I don't really know the mechanism. You can test your own tires by making a run, then letting ~4 PSI out of your front tires. Make another run. If the car pushes more than it did before, then your tires want higher air pressures. If the car gets tail-happy, then your tires like lower pressures. It's a bit crude, but it can get you a pretty good way to finding where your particular tires like to run.

Oh, also--higher air pressures mean that the tires squirm less, and they tend to build up less heat. That might possibly help keep your tires from getting "greasy" as quickly.

--DD