dkms2k

I am fairly new to Autocross (3 events) and about to purchase a set of Dunlop Star Spec Z1's for a set of stock rims I recently acquired as my dedicated Auto X wheels/tires. I currently run A Stock and plan on running it for a full season next year (I may run some STR as well.)

I see where in the Autocross FAQ's people are now running 245s all around on AP1s. My question is are you running 245's on the stock front wheels with the 6.5" width or are they going to a 7.5" width wheel? I'm assuming to stay in A Stock I would have to run 245's on the stock 6.5" wheels and am curious how the wider tire on the narrower wheel works out.

Also, what kind of tire pressures would anyone recommend starting out with with either the staggared or non staggared setups for a stock AP1?

Thanks in advance.

captain_pants

I run 245 Hoosiers all around and 225 Dunlops all around for street use.

The Star Specs don't come in 245 in the 16" sizes, only 225. I'm running four of those with the stock front and rear wheels. They're slightly pinched on the front vs. the rear. You need a bigger front bar with this setup. I've only done two days of the SoloPro school and some test and tune at Nationals but I liked 40 psi all around in the Dunlops. Lower the rear if you want more oversteer. Tire wear was even and the car was quite quick in the rain at the T'n'T.

If you run on a bumpy lot the 225 or 245 tires on the stock 6.5" front wheels will rub on the inner top edge of the fender liner, even with a giant front bar.

dkms2k

I guess I should have checked to see if the 245's were available before I asked.

I'm currently only running the stock front bar (that will likely be my next upgrade - but I'm not sure when) and I know that several of the regular event locations have some pretty rough transitions - so I will probably just stay with the staggered setup.

I've been running the all season Kuhmo Exsta AST's that the previous owner had put on the car and have been waaaaay loose in the rear end - so I am definitely looking for less oversteer.

Thanks for your input.

jeffjanzen

You are going to notice a HUGE difference between the Kumho AST and the Z1 (ASTs are garbage).

Like Corey says, to run a square (AKA non-staggered) setup, you'll want a bigger front bar. If you won't be changing the bar for a while, get narrower front tires (and two pairs of rears - they wear out roughly twice as fast).

dkms2k

That is my hope. I've still been finishing mid-pack while spending almost as much time counter steering and fighting to keep the rear end in check as I have been trying to hit my marks and stay on course. I figure if I can get a little grip I can be competitive (at least in the Novice class.)

I was told that those AST's were crap. I plan on running them as DD tires until they're shot and then I'll get a better all season performance tire.

Thanks for your input as well.

captain_pants

Don't forget that to be really fast you need to drive to the limit of the tire and not over. By this I mean that if you're sliding around and working to catch the rear end, you're overdriving the car. Buying grippier tires will work for a while, but learn to drive at the limit of your current tires and you'll be faster with no money down. Work on braking a touch earlier and then applying throttle (gently and progressively) earlier in the corner. More weight on rear tires = less oversteer.

I struggle with this constantly. Tim Aro (SoloPro instructor) gave me a thought exercise: you want the rear end tracking 4" outside the front in a corner, not 14". Kind of a no-brainer, but thinking about that really clicked for me while on course. That'll make you faster on any tires.

EDIT: I should add that your tires are certainly crap for autocross. But treat them as a learning tool instead of a hindrance until you can replace them.

Forcednduckshn

My thoughts on this too. Be delicate with your right foot. Exercise patience when you get back on the throttle. Power oversteer is fun, usually slow. That said, at the limit of the s2000 you are going to be making subtle precise corrections much more so than other cars. The balance is biased towards rotation and tossabillity so wait the extra tenth of second to get back on the throttle once the suspension settles.

dkms2k

I have continued participating simply for the practice/experience and opportunity to learn the limits and dynamics of the car/setup - even though I know I won't be competitive on these tires. I've experimented with air pressure in the rear which has helped a little. I have gotten quicker and more competitive - from 12th in my second event to 8th in the third and I generally improve my times from lap to lap.

I had one of the Club's Senior Officers and Drivers ride with me and then drive the car (and he subsequently spun it in the second sweeper.) He got out of the car shaking his head and just kept saying that I had to get some grip in the rear end of this car.

My mindset is to use the 6 events I will run this year as a learning/school of hard knocks season (I need to learn as much as I can the hard way first) and plan on attending the Club's Annual Autocross School in February/March as well as at least one more driving school and going from there.

Thanks for your advice.

Forcednduckshn

You at least have intelligence on your side. Idiots come and go here, you'll see that soon enough. Good luck and kick some ass.

dkms2k

I have noticed. I'm just glad none of them showed up in this thread.

Thanks to all for the advice.