-2.7

 

I run an aggressive spring/shock combo along with a big front bar. My car doesn't move much.

 

Will be fun trying to keep up to the beast.

 

I am considering a square setup as well. The charts I've seen say a 285 will fit a 9.5 in wheel (guidelines were 9.5 to 10.5 in wheel) My Z is pretty much 100% stock...will 285's fit without any issues?

 

I'm surprised everyone is going 285's with only a couple track days.

I've used my 265/265 setup for the past two years and have no complaints.

I'd think too massive of a tire will hide driving flaws just like a stickier tire would.

 

^ By that logic, why not drive on the stock 245 potenzas?

 

That's an interesting question... I think I have too wide a tire sometimes. :P

 

I did for my first 4 HPDE's.

And I think fixxercask did as well (and he was still flying by others with grippier tires)

 

I agree with this statement. If you can learn chassis dynamics and car control with the OEM size tires you will be that much better when you are ready to move up. It's best to learn that on skinnier and non-R compounds.

 

285 rs3 runs wide, really wide. My sidewalls are dam near straight up and down on a 10.5 , search a little I believe pics are posted.

 

Although a 285 will fit on a 9.5" rim, there have been a few tests lately showing that it is better to have the tire a bit stretched than a bit squished on the rim. On a 9.5" rim your lap times will probably be the same going with a 275 tire (or maybe even a 265 tire) as with a 285 tire since you will not be using the same amount of contact patch as you would with the 285's on a 10.5" rim.

Obviously, there are differences in tires (tread width, sidewall stiffness) that make this more or less pronounced but I would shoot for at least a 10" rim.

 

I am running a square 245 R6 on 9.5" wheels this year due to rule changes, so far so good! The turn in response is better from the 255s I used last season is better since they fit the rim different. They also feel like they dont scrub/push as bad in tight turns.

There is such thing as too much tire. I like to reference spec miatas in this case. A SM on 225s is slower than an equivalent car on 205s.

 

Also depends on the track. My 350Z was marginal faster around AutoClub Speedway on V710 245s then 285s, but the test wasn't on the same day so its just anecdotal. When you spend a lot of time at full throttle on a straight or in banking (20 seconds at the Speedway) narrow tires are better.

 

Im actually also in the market for 285s on a 18x10.5 wheel. Would they fit on basically stock suspension?

 

does everyone still run more front camber than rear even with the square setup? if so that's a big big big grip change in front, is the car neutral or slightly oversteering now?
what's the camber specs front and rear for those that are running square? thanks.

 

The front needs all the help it can get and yes you'll want to run more static front negative camber. Even with a square setup the car still understeers. It undertsteers less, but the basic chassis still understeers at the limit.

 

That has been my observation... For a while, I thought my suspension setup was just way off because I've been complaining of general understeer with 275/275 setup while others have mention "oversteering monster". Mated with a Cusco diff, I don't get very much rotation unless I trail brake very aggressively (which I only do in sharp corners).

 

A lot of people confused lift throttle behavior with steady state behavior. When a car is decried as understeering or oversteering it means its behavior in a corner at a steady state (steady throttle, steady steering). A good handling car should step the back out under lift throttle. The more sensitive the suspension and car is to throttle the faster you can go around corners - assuming some driving skill.

 

Under steady state throttle, my square tire setup does understeer. With the stock VLSD, my car was more sensitive to throttle lift. After the Cusco RS install, it wasn't as sensitive anymore. In fact, I'd say it's borderline numb. It's set up as a 1.5 way at 80% locking. I remember reading somewhere that these LSD's will add "stability" in turns while off throttle, thereby allowing more "confidence" under trail braking. When, I read that, I concluded that it meant the car does not rotate as well under throttle lift, and I must rely more on trail braking to get the car rotated.

 

Any time you lock two wheels together you increase the tendency of the chassis to move in the direction those two wheels are pointing. Trying to change that direction becomes more difficult.