Now you have me worried that I'm ruining the handling of my car. Stock setup has a 8.9" width up front and a 9.6" in the rear resulting in a .7" difference in the two. The 255/40 and 295/35 setup I'm looking at it 10" width in the front and 11.6" width in the back translates to a 1.6" difference.

 

It won't ruin it per se but it will give the rear more traction than the front, thus producing more understeer - even more so than the Z had stock. The Z understeers quite a bit stock primarily because the engineers designed it that way for safety reasons but also because of the staggered tire sizes. I personally wanted to reduce that so I reduced the stagger to 10mm. I would have gone square if the wheels I wanted came in a square setup but they didn't.

 

^^ Dead on.

But beyond tires, there's lots of ways to counteract under/oversteer depending on what one wants. Adjustable sway bars are the easiest and best way to tune this by "dialing in" as much of either condition as you want; then, when you've reached the maximum amount of either condition, there's still shocks/springs to further dial in or out roll stiffness.

When customers used to ask me for my recommendations on track set ups or hot street/canyon tunes, the first thing out of my mouth is "Fit the tires you want/can run for your specific purpose - sometimes sanctioning bodies will dictate min/max - THEN based on the tire setup, go for the hardware needed to tune it further.

OP, you're splitting hairs here. I suggest you go with the "generally accepted 20mm width stagger on 1" stagger width wheels THEN consider your next step. Be it 255/275, 265/285, 9/10, 9.5/10.5 or as others have advised, square it up if it fits, then move to the next step.

 

With that advice, I'll probably go with 265/275 and 9.5"/10.5" wheels. I can't get the PSS in 285/40.

 

I might be able to get away with 275/35 295/35 but then I'd have a .4" drop in the front and a .6" drop in the back. I don't want to lose ground clearance.

I'm using this site to get my tire measurements.
https://tiresize.com/comparison/

 

And... If you mount 35 series in the sizes you mention, you will have a noticeable gap (tire to fender).

 

*facepalm*

 

255/40 & 275/40 gives me the exact total diameter and sidewall as stock. Looks like I'm set.

 

That's a great combo

 

So I've been working with a distributor to figure out proper wheel and tire combo that will fit. I started out with what I have in my first post for the rears: 18x10.5 25 offset with 295/35 tires, he says I will not need to roll my fenders. I've decided to scale back a bit due to the limitations of sizes on these Michelin PSS's. Now I'm looking at 18x10 22 offset with 275/40 tires. I'm being told that I will have to roll my fenders for these. I would think I wouldn't have to roll my fenders with this smaller setup but I'm not sure. I'm using these 2 sites to plug in the numbers and it looks like I'm safe with the new setup of 18x10 22 offset with 275/40. So..........

http://www.willtheyfit.com/index.php...culate#content

https://www.1010tires.com/Tools/Whee...et-Calculator#

 

Youll have to roll if youre lowered. In sitting on 9.5+24 with 40 and im lowered by 1" and had to pull front and roll rear.

 

I'm sitting at stock height. I don't plan on lowering either. If I do, I'll roll then.

 

With stock, you SHOULD be able to get away with it. But that depends on how heavy you and your passenger are. Haha

 

Ha. I'm never more than about 325lbs with me and my other passenger. Usually it's my gf and together we're less than 300lbs. I need to scale back a little on these tires because 275 is the highest I can go with the 40 aspect ratios. 285's & 295's are at 35. That's too much gap.

And as far as understeer goes, I've never had a problem. I do push it hard on some mountain roads but never noticed any understeer. I keep hearing the Z's are prone to it with the staggered setup but with my driving, this setup shouldn't be an issue.

 

Like mic said earlier, lots of ways to combat understeer. Not just tires. I would do 265/40 just to be on the safe side.

I run 275/35 all around and my car oversteers ALOT. And i like it that way. However, others who drives my car, gets nervous base one the amount of oversteer.

Its mostly about how you drive and your preference.

 

It's cause you are nowhere close to the limit

Square , unless you do plenty to the suspension will still understeer. Also , you could have throttle Induced oversteer, that even easy to do in stock form.

 

Here they are. Enkei GTC01RR 18x9.5 et22 up front with 275/35 and 18x10 et22 in the rear with 295/35. These Michelin Pilot Super Sports are amazing.

 

Good call on tire sizes and Enkeis (always!) Eibach Pros are whispering in your ear lol.

 

I'm definitely going to get a set of coilovers. Not sure exactly which ones though. I don't need full on race since this is my daily(ish) and I don't want to be scraping the ground. Next upgrade will be either the Akebono big brake kit or a LSD. I'm looking at the Quaife. I'm always open to suggestions on those.

 

Very nice set up.

And very nice location. Looks like Great Highway, ya?

So what do people have against static suspension setups, anyways?? Unless you need to adjust for track conditions, not sure why so many people insist on coilovers... Note that I'm not dissing anyone's choice by any stretch! But at under $2k for static complete with alignment adjusters, TOP LINE shocks, springs, bars, I'll take that bit of predictability, shock & bar adjustment any day over GOOD coilovers starting at near that price.

Just my devalued $.02...