Blue Liquid

Likewise, I couldn't give a damn about TC or VDC. It's the ABS I don't want getting screwed up. I use R compounds for daily driving, so I don't want any problems with ABS. Sport Compact Car put a Stoptech 13 inch brake kit on a Z, along with wider, stickier tires, and the braking distances were increased significantly from stock. They blamed it on a camber issue, with less tire in contact with the pavement during braking, but now I wonder if it wasn't also something to do with the wheel diameter being off too much and their ABS wasn't modulating properly.

EnthuZ

iTrader: (2)

An early HAPPY BIRTHDAY, Blue!

I don't think the ABS will be affected....not sure though. I need to abuse my 040's a bit more. The ABS did kick in a couple times with my OEM tires, but it was not a bad thing......but I was USING my brakes!

I do think that SCC is correct, in that the EXTREME negative camber had detrimental effects on their braking distances....Harder braking=more weight transfer=more front suspension compression+even more neg camber=less tire contact area!

2003z

iTrader: (7)

everything works properly on mine with 255/40 at all 4 corners.

D'oh

When I drove the Z at a wet autoX, it seemed to be better balanced than in the dry. I think it felt that way because I was a little calmer going into the turns and due to the reduced traction, it was much easier to use the throttle to rotate the rear.

I've found the Z to understeer if you go hard into a corner or if you are in a long sweeping corner and you gradually approach the limit. In those cases, it seems like the front slides first always. If you go easier into a corner (but maybe turn in harder) and accelerate hard out of the corner, then the Z seems to be balanced a bit better.

I'm still an inexperienced driver, but what I've written above is what I've experienced so far, both on the AutoX and road course.

-D'oh!

drivesolo

iTrader: (6)

I've been following this post for about a week now and it looks like the general consensus is that as far as autocross goes, a 17" wheel is better than an 18" wheel.

I'm probably lacking some knowledge here, but wouldn't a larger wheel result in a lower and stiffer sidewall (assuming you try to stay at the same tire diameter) and therefore better handling? Is this just a generalization? Is the reason for going with 17's other than performance, like cost and better selection.

I've been in several autocrosses so far and I've been running bone stock in my Performance model. I've got the 18" wheels but not the Rays, I've done pretty well so far and placed in one of them. I might be under driving the car a bit because I feel like I can go at it harder or maybe the understeer has me a bit confused when it comes to trying to get my end around.

I'm looking to get new wheels and tires but I'm finding that trying to take in all the variables is a little overwhelming so I've been trying to stay to stock dimensions as far as wheel and tire sizes with all the wheels and tires that I've been looking at. Sounds like this probably won't get me the best results. I could use some advice considering that I'd like to keep the purchase of wheels and tires in the $2k range. Is this possible or should I just go for good street tires before getting a dedicated set of autocross wheels?

2003z

iTrader: (7)

if you want to stay in stock class, get 18x8s with the same offsets. I went 17 because they were less expensive, lighter and had more choice in tire sizes, but I'm not running in stock class either.

raceboy

I went 17" because the choices in R comp tires for 18" stinks!

drivesolo

iTrader: (6)

So the difference in sidewall stiffness between 17" and 18" shouldn't be much huh? I'd like to know your opinions on that. Are you finding that you need to run a lot higher tire pressure to compensate?

I'd like to go the cheaper route since I plan to be running this car for a while. Looks like the difference between 18" and 17" tires is significant enough for it to matter to me in the long run.

Blue Liquid

Yeah, like raceboy said, the R compound tire selection is practically nonexistent for 18 inch wheels. However, there are many for 17's, as there's lots of support for professional racers using 17 inch wheels (lighter, etc.). Additionally, tires for the 17's will be less expensive than for the 18's. The difference in sidewall stiffness is minimal, as race tires have the stiffest sidewalls around. And besides, sometimes you'll run a 40 or 45 series height in a 17 or 18 inch wheel (i.e. 245/45-17 or 255/45-18).

Veritech

Hi, new poster here but I've been lurking for a while.

tiny bit of background before the questions:
I am from Montreal, Canada. I do the occasional auto-x (solo2) but very much into solo1 (time trials). I also do tarmac rallys, winter rallys, winter auto-x, hillclimbs, etc etc (not all with the same car of course).

So my question is, what has the braintrust decided for largest tires front/back?
275/40(or 35?)/17 all around on 17x9x35 offset wheels? (on the track package)

I am keeping the car stock besides shocks, intake and exhaust (to stay in stock class), so I'd like to get the most rubber possible.

if someone could give me a definite answer I'd be grateful.

thanks,
Liam in Montreal

Blue Liquid

Veritech, I was told by tirerack that 275/40-17 on all four corners would retain the stock diameter, in case you're concerned about any electronics being negatively affected by running differing diameters (i.e. ABS, TC, VDC). However, they weren't sure about the possibility of a fender roll or other front fender modifications. In other words, a 275 width tire on a 8.5 inch or wider rim might require front fender modification. So under full lock-out turns or heavy suspension loading, you may experience tire scrub.

2003z

iTrader: (7)

given the correct offset, 275s all around should be fine. I've seen a nat'l champ auto-xer's car running 275s at all 4 corners on the stock enthusiast rims.