Crossfire competitive in DS?

Keith Vail · **Posted:** Sun Oct 15, 2006 9:26 pm

Ok, I know not really many people have tried to compaign them on a high level but I have a 2005 base model, which is the lightest one you can get. It has 19x9 inch rear wheels but I did some measuring this evening and from the information on the Tire Rack website I can fit a 325/30/19 on the rear wheels. I know the Solstice guys are shoving 285s and 295s on the 18x8s so I figure I could go larger on a 9 inch wide wheel. The front tires would be limited to either a 245 or 255 on the 18x7.5 inch wheel. Anybody have an opinion on the car? It is classed in DS and I feel it could have enough with a good driver and prep to give the BMWs and ITRs a run for their money.

Kevin Butler · **Posted:** Sun Oct 15, 2006 9:44 pm

Keith,

The son of one of my associates at work has also recently acquired an '05 Crossfire for autocrossing. He's in the Charlotte area. I'll try to get contact info for you so you two can trade notes.

KB

Donnie Barnes · **Posted:** Sun Oct 15, 2006 9:52 pm

Couple things...first, those things push like a dump truck in stock form. I can't imagine what they'd do with that much meat in the rear and that little meat in the front.

Second, you sure you can get tires that are within 10% in circumference front and rear? If not, you may have trouble from the traction control system, even when "disabled." That was a limiting factor for what tire combinations we could try on the Cayman for that reason.

Seems like maybe there was a thread on SCCAForums.com about them that had some bad things to say, too. I'm betting they just plain weigh too much. I know in 2005 they had to end the celebrity challenge early because they corded the shit out of the outside shoulder of the OEM tires on the cars they were using, and they really didn't see that many runs where people were driving them *that* stinking hard. I was astounded, to be honest (and yeah, they were aired up).

--Donnie

Keith Vail · **Posted:** Sun Oct 15, 2006 10:08 pm

Thanks for the quick opinions. I doubt they weigh too much. My car easily weighs a 200 lbs less then a BMW 330. I will be running it at the Triad Dixie event on a couple weeks, so that will be the first competition opinion I have of the car. I am surprised they corded the outside of the tires so much considering it has double wishbone front suspension and my car has over -1 degrees of camber and I have yet to actually align it to see if anymore is available. I have about 3000 miles of street driving on it since I bought it and my first opinions is that it is miles better than my WRX was even though my WRX has sway bars, camber bolts, and stiffer springs.

Coming within 10% isn't a problem on the rear atleast by the numbers I get from specs charts. The Hoosier is supposed to be about 26.8 inches in diameter an the stock Continentals are from my measurements 26 inches and Tire Rack says they are 26.1 inches in diameter. So that is within 10%.

PS. Thanks Kevin. Two heads are better then one if I decide to set the car up and go that route.

Donnie Barnes · **Posted:** Sun Oct 15, 2006 10:26 pm

You only need to be within 10% between front and rear for the TIRES ON THE CAR AT THE TIME. Sorry I wasn't more clear on this. So your Hoosier fronts need to be within ten percent circumference of your Hoosier rears. Doesn't matter if that's different from whatever OEM tire you have or not. Traction control only gets confused when it starts getting wildly different readings from the front and rear tires while the steering angle is near zero...it thinks something has to be sliding.

Hope that makes more sense now.

Not all Hoosier sizes are the same diameter, obviously...

--Donnie

Keith Vail · **Posted:** Sun Oct 15, 2006 10:33 pm

Sorry Donnie, I misunderstood that. The front Hoosiers are listed at 25.3 inches in diameter and the rears are listed at 26.8. If my calculations are correct that should be within the 10% you stated. God I hope they are correct otherwise I should hide in shame that I am in my fourth year of college and can't do simple math. :lol:

Thanks again for the quick responses. I am just curious if this car I have sitting in my garage really can be quick or not.

Donnie Barnes · **Posted:** Sun Oct 15, 2006 10:54 pm

Hey, all it costs are some tires, an alignment, and some seat time to find out.

Let me know if you want a codriver. *cough*

--Donnie

Chuck Branscomb · **Posted:** Mon Oct 16, 2006 7:24 am

Keith,

I can't imagine you running 325's on the rear with a 245/255 up front if the car in stock form is already prone to heavy understeer. The 330i ZHP is prone to push a fair amount at the limit in stock form. I have it aligned for max negative camber up front (only -1.3 degrees though), and I'm using the same width tires, front and rear, even though I have to run 8" and 8.5" rims in stock class. The car comes with 225/40-18 up front and 255/35-18 in the rear, and I'm doing the mortal sin at the moment of running 225/40's all around (Dunlop SSR track-type R-comp tires so they need the heat

). It is much more neutral balanced with the same size tires front and rear coupled with a 3-4 psi pressure differential.

I would be inclined to look for a front/rear width as close as possible to better balance out the understeer.

Chuck

P.S. BTW, I do have some Hoosier A6 245/35-18 tires for sale. Two of them are brand new, never mounted, supplied direct from Hoosier a few weeks back with a week 34 / 2006 mold date. The other two (week 20 mold date I believe) have 16 runs on the rear of the 330 at the NCAC and have the very little wear according to the tread depth measurement (no sidewall rollover on the rears either).

Keith Vail · **Posted:** Mon Oct 16, 2006 9:28 am

I understand the sizes are less than optimal but the problem is that the smallest size in a 19 is a 315/40/19 and that is 2.5 inches taller than stock compared to the 325/30/19. The 19 rear wheels IMO are what has killed the cars competitiveness. I know someone ran 18s all around because that is the factory specified winter setup, but he got protested and the protest was upheld. So I can't run the 18x7.5 all the way around like I originally was told when I got the car. I might just email SCCA to get a clarification on that ruling but I feel it is already a dead issue if a protest on it was upheld.

Edit: One saving grace is I just found that Chrysler sells factory crash "camber" bolts and can be adjusted up to -1.8 degrees camber in front. I had thought about running sticky r-comps on the front and just some really good street tires on the back to get a less understeering balance, can anyone comment on that.

Aaron Buckley · **Posted:** Mon Oct 16, 2006 9:38 am

Keith Vail wrote:

I understand the sizes are less than optimal but the problem is that the smallest size in a 19 is a 315/40/19 and that is 2.5 inches taller than stock compared to the 325/30/19. The 19 rear wheels IMO are what has killed the cars competitiveness. I know someone ran 18s all around because that is the factory specified winter setup, but he got protested and the protest was upheld. So I can't run the 18x7.5 all the way around like I originally was told when I got the car. I might just email SCCA to get a clarification on that ruling but I feel it is already a dead issue if a protest on it was upheld.

Edit: One saving grace is I just found that Chrysler sells factory crash "camber" bolts and can be adjusted up to -1.8 degrees camber in front. I had thought about running sticky r-comps on the front and just some really good street tires on the back to get a less understeering balance, can anyone comment on that.

Keith, I remember the protest and it will be upheld. The issue comes down to that you cannot buy the car from the factory with 18x7.5" rims only. Also, be careful about the crash bolts. Lots of manufacturers sell them, but unless they specifically reference them in the factory service manual, you cannot use them legally in stock.

If you wanted to do the stickies up front with streets in the back, go with Toyos or something that is not that far off of a street. Hoosiers or V710's up front with even Azenis or the like in the rear will be an oversteering mess. - AB

Keith Vail · **Posted:** Mon Oct 16, 2006 9:43 am

Ok here is my new setup ideas after discussing somethings with a guy out in California who runs NASA Time Trials with his. I can only fit the 225/40/18 in the front, the 245 will rub the upper A-arm. My stroke of thinking is to put either the Pirelli Pzero Corsa System or the Michelin Pilot Sport Cup on the back in either a 265/30/19 Michelin or a 285/35/19 Pirelli. Can anyone share their thoughts. I know it is less than ideal but putting a harder compound rear tire on the car will effectively make it push less and I am just crazy enough to try it.

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

Keith Vail wrote:

I can only fit the 225/40/18 in the front, the 245 will rub the upper A-arm.

5mm spacer? Would it clear? BMW guys do it all the time.

Aaron Buckley · **Posted:** Mon Oct 16, 2006 9:51 am

Keith Vail wrote:

Ok here is my new setup ideas after discussing somethings with a guy out in California who runs NASA Time Trials with his. I can only fit the 225/40/18 in the front, the 245 will rub the upper A-arm. My stroke of thinking is to put either the Pirelli Pzero Corsa System or the Michelin Pilot Sport Cup on the back in either a 265/30/19 Michelin or a 285/35/19 Pirelli. Can anyone share their thoughts. I know it is less than ideal but putting a harder compound rear tire on the car will effectively make it push less and I am just crazy enough to try it.

225 up front? Ouch. I would consider the Pilot Sport Cup, but my guess is that you will still end up with a push. - AB

Keith Vail · **Posted:** Mon Oct 16, 2006 10:06 am

Aaron Buckley wrote:

225 up front? Ouch. I would consider the Pilot Sport Cup, but my guess is that you will still end up with a push. - AB

Yes but I wonder if it is a push that can be tuned out with some good shock tuning. The 225 thing really hurt but I know this guy has been running his Crossfire for several years and said it will literally shred the tire, so it isn't just a minor rub that can be fixed with 5mm spacers.

Aaron Buckley · **Posted:** Mon Oct 16, 2006 10:35 am

Keith Vail wrote:

Yes but I wonder if it is a push that can be tuned out with some good shock tuning. The 225 thing really hurt but I know this guy has been running his Crossfire for several years and said it will literally shred the tire, so it isn't just a minor rub that can be fixed with 5mm spacers.

I'd save my money and put tires on the Miata. DS will be changing with the '06 WRX as well as the MazdaSpeed 3. - AB

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