Autocross?

[Tank]

Where would you find 225/45 track tires? I can't find anything at the Tire Rack that matches up with 16" front rim. I don't think that the stock 15X6.5" front rim I currently run will accept anything wider than a 205.


[/b]

I'd like to go with something stickier in the front for AutoX (ie., wider than 205) and I was wondering what your wheel/tire setup is? How is the availability of tires for you? I've got my car lowered with a TEIN RA setup and I've been warned that 235 might be too big to run in the front, but I can't find any tires in 225 that would seem to fit.

Thanks for any help! [/B]

There are 4 tires that should fit the 16" rims fairly well.

Kumho V700 Ecstas in 225/50
Kumho V700 Victoracers in 225/50
Hoosier A3sO4 in 225/50
Falken Azenis RT-215 in 215/45

The first 3 are about an inch bigger around and might rub a little at full wheel turn but that shouldn't be a big issue. A small price to pay for more grip. (just harder to make a tight turn in grid) You might check around for some used tires from friends or competitors and spend a little to have them mounted on your rims to see if they fit to your liking. That's what I did.

If you're not in the running for first place in your class at the moment, I would highly recommend the Falkens. They're the cheapest of the bunch and will last the longest - plus you can use them as a street tire as well. Unless you're already very competitive, people tend to put too much emphasis on the tires. If you're 4 seconds behind the leaders why pay $400 more than you have to for a set of tires that wear out quickly and at best could only give you a 2 second advantage? Wait until you're 2 seconds behind and then trade up. Trust me, if you really learn to drive you can come within 2 seconds or better of R tires while using almost any good street tire. Save the juice until it can pay off. Work on suspension and alignment first, there's a bigger bang for the buck there. No sense in burning thru good tires while you figure out toe and camber, etc.

I'm running 17" Volks front and rear: 7 1/2 and 9 1/2. Victoracers in front and Ecstas in the rear. (OK, that's an experiment) but I'm pretty happy with that. I use the Kumho MXs for practice days. I'm lowered as well with Konis and H&R Sport springs (3" off the ground) and the 225/45 just barely fits in front. There are a thousand ways to go. Just pick one and start to work with the other variables. It's a never ending process.

T

 

[Departurediver]

OEM

It seems like the tires being discussed either have a treadwear of 50 or 200. Anyone try the OEM Bridgestone RE010's for this event or hear how they work? BTW, thanks Tank for all the info. Also, will the Victoracer 275's fit on my 17x8.5. If not, it looks like I will have 225/50/16 and 245/45/17's. I have other wheels/tires I will use for the street. But for now I'm going to use my stock wheels for autocross.

 

[djvarg]

Tank, thanks for your reply a while back regarding my autocrossing questions. Do you know what the maximum negative camber that I can get (front and rear) with the stock suspension? I had a good time autocrossing last weekend. Everything is still completely stock, with stock alignment settings (Front = 0 camber, 10’ toe out, Rear = -1.8 degrees camber, 30’ toe in). I am running Pilot Sport tires in A-stock-street tire class. There is still a lot to learn switching over from my 135HP MR2 to an NSX. The car had significant oversteer. I am trying to decide what size front sway bar to go with. It depends on how much negative camber I can get in the front. If I can only get –1.0 degree, a 7/8” bar should be a good start. If I can get up to –2.5 degrees, I may need a 1” bar. That reminds me. Do you or anyone reading have a used aftermarket bar that is not in use that you want to sell? Thanks for you help so far. Dan

 

[Tank]

Dan,

As I'm learning here, the road to a perfect set-up is VERY long. I had a long-running battle with over-steer and finally beat it.... only to make one more change and ended up with under-steer. Since I corded my front Ecstas, I put on those bigger Victoracers.

Well, yesterday the victoracers worked great - the front end stuck like glue, really sharp turn-in, great response. But the rear is back to stepping out with any real throttle in a turn. The tires are just too different to be used together, even to compensate for another problem. So I lost ground chasing the M3 that's leading my class. Drat! But that M3 is one hooked up car.

Your rear settings are about what I'm running right now. I dialed back my rear toe-in just a bit to .25 from .30. I found 30 to be a little too much tire wear and I think I can get the same results with shock and sway adjustments. With the stock suspension parts all I could get was a -2.0 for front camber. Most of my competitors run much higher neg camber. So I bought a Comptech camber kit. As installed it gave a -4.0 and I dialed it back to -3.0 which seems to be working quite nicely. My Comptech front sway bar is set on the softest setting.

My biggest problem is I keep violating the golden rule of set-up: ONLY CHANGE ONE THING AT A TIME. But in autox, there is so little T&T time that I feel I have to try too many things at once or else it'll take years to dial in. But then again I'm waisting plenty of time figuring out which changes caused the current effect.

Anyway, it's all about having fun with the greatest car in the world!

t

 

[djvarg]

Tank, I autocrossed my car last weekend with a newly added Comptech front sway bar. With the sway bar set on the stiffest setting, the car was balanced very well. It understeered slightly in the tight/slow corners and over-steered slightly on the higher speed corners. Since the balance is good now, I want to increase the same amount of negative camber front and rear. You mentioned that with the stock set up, you could only get 2 degrees negative camber. Is the true for front and rear? I want to max out the end that is the limiting factor, then change the other end by the same amount. Thanks. Dan

 

[Tank]

Hi Dan,

Sorry its been awhile, I'm out of town for a work assignment.

I would say if you feel the car is balanced right now, leave it alone. I don't like any understeer but I can live with some oversteer on corner exit. With the understanding that understeer can come from simply over-cooking the corner entrance or early apexing. My increased negative camber is in the front only. The rear toe in is a more important setting back there IMO.

Let me know how you're doing compared to others in your class and the faster classses.

t