Z33E

Alright, I was wondering what the handling on the car is going to be like if I'm going to be running 18 x 10.5 +22 rear and 18 x 9.0 +20 on front. Don't know what tires yet only size 275/40/18, don't plan on tracking just don't want the car to handle like a massive load of ***. Thanks guys.

rearranged

It seems to be a pretty popular size for rear wheels on a z. I don't think everyone would be running 10.5" rears if it made their car handle like a massive load of ***.

MicVelo

Jeez, man, yer overthinking this a bit. Not a bad thing, mind you, as I understand being new to tire sizing and such but eventually you're going to find out that the suggestions people have made are all good, solid suggestions based on experience. The other thread you started went through who knows how many iterations on the sizing of everything.

Let me tell you a few things to expect with regards to your question above.

The sizes and offsets you've been going back and forth with in this and your other threads are LESS IMPORTANT than picking the right grade of hardware. Strong, light wheels and good tires that respond and grip well are more important.

As an example of this, I ran Track V1s (8, 8.5, 17-18lbs/corner) with sticky Max Perf tires and that was truly as capable as anything that I've had on the car since (only exception being my current setup).

Your wheel size choices are fine - in that they will give you "the look" AND commensurate uptick in handling performance provided you choose wisely.

When you ask "what's the handling going to be like?", there's no way anyone can tell you definitively because nothing has been decided upon. However, when you move up to larger tires and wheels, here's what's going to happen on a general basis:

- You will notice a seeming drop off in turn-in response. The larger you go, the less lively it will seem. This is simply a matter of unsprung weight. But that's normal and it's a fine line tradeoff between loss of response and higher ultimate grip.

This is yet another reason why I advocate sane tire sizing as my knowing that the car is going to do precisely what it's asked to do when I turn that wheel is as important to handling as upper end grip is.

- Tactile sensation in the wheel even over smooth surfaces will drop off. The feel will be more "dead". Even moreso depending on the tire and wheel choice, particularly due to weight increases at each corner of the car. Again, same reason and rationale as above.

- That all said, you will find that the steering characteristics SHOULD remain roughly the same unless you're planning to run 275s square. A square setup will reduce understeer some by enhancing front grip but may possibly add oversteer depending on the tires you use. Be careful with that. Driving the car will require more attentiveness until you are used to the new steering attitude closer to the limits.

So with that, the bottom line is this (reiterating above):

Light, strong wheels + high response, high grip tires = Nice difference in handling from stock. But will have a different feel.

jv350z

iTrader: (6)

what tires (model and sizes) did you run w/this combo?

MicVelo

On my Z33, OEM size (225 &245-45) Sumitomo HTR Z3. Overall grip at limit not what my current 255/275 is but lively, fun, controllably tossable these were for sure.

Currently, these wheels are on my Z31 Shiro shod with 255/40-18 Conti DWs all around. I think.... bought two from a friend then bought two new ones from TR for the front.

Phenom

iTrader: (4)

Weight is probably the more important factor when trying to determine how wheels will affect performance. With 10.5" wide wheels, you can get into some boat anchor weights if you go with cheap wheels. On the other hand, it's possible to find wide wheels without them being too heavy. For example I have 19x10.5 rear wheels that weigh about 20 pounds per wheel.

terrasmak

iTrader: (8)

I ran 10.5 with 275/40 out back when mine was a street car. Great setup

CK_32

iTrader: (1)

What are you running now??^^

terrasmak

iTrader: (8)

10.5 square, 285/35-18 on one set of wheels, 275/35-18 on the other set.

CK_32

iTrader: (1)

What benefit does square have? I thought square had major getting limitation.


I'm getting ready to start setting up for track and auto x days and am looking for new wheels and tires. I was thinking of 10rear and 9.5 up front. But after reading a bunch of these threads I'm as confused as the first day I googled which size wheels should I buy lol

terrasmak

iTrader: (8)

Much less understeer for track use

CK_32

iTrader: (1)

Really? I would think it would add more under steer being square.

MicVelo

Nope. Equalizing F&R tire sizes adds more relative traction to front with regards to rear. Net result is front biased adhesion vis rear, hence reducing understeer.

Note that terrasmak (and me now) did not say "it will oversteer". Not quite true... it just reduces understeer but not eliminates necessarily or altogether. To achieve true oversteer in a Z, you need to increase rear roll stiffness so that rear tires will achieve their max slip angle before the front (up to and sometimes exceeding the limit of adhesion at the rear of the car).

Z's were designed from the factory with understeer so as to avoid product liability issues; hence medium stagger.

CK_32

iTrader: (1)

Man you guys are so dam close but yet so far.

Your the type of Z guys I wanna sit down and have a beer/share a track day tent with. Help me get my info straight and my Z a proper set up.

terrasmak

iTrader: (8)

I will be back out at another Corner 3 Nissan Challenge event soon. Can easily happen, we also have a lot of track minded people at the events

CK_32

iTrader: (1)

Those are the guys I'm looking to meet. Ive got a bunch of buddies who are still knowledgeable but none that have Z specific knowledge.

I thought about hitting the last one but am far from ready to even bother TBH.. Like I said I still have a lot of proper mods I wanna get to before I start spending time at track days.

MicVelo

While I haven't been on a track for any real high speed stuff other than a few ride-alongs at MLSIR and in Vegas in years, the way I always looked at it was, "The track is the great equalizer. Spending time on same is where the driver's flaws show up and tell me what I need to work on....

....Oh, then I'll get around to worrying about the stuff on the car."

Phenom

iTrader: (4)

Question for you guys since we're on the topic. I've recently had the square vs staggered discussion because I am way too familiar with the Z understeer after some autox sessions. I said I would eventually be looking for a square or less staggered setup to reduce the understeer, and someone suggested instead to just increase the stiffness of the rear sway bar influence the car to be more neutral.

While I understand how this would reduce understeer, fundamentally it seems foolish to me. Increasing traction for the end with less traction seems like the only proper approach whereas increasing swaybar stiffness simply takes traction away from one end. It's sort of like saying, "my left arm is stronger than my right arm and I wish they were equal, so I'll just make my left arm weaker (as apposed to making the right arm stronger)."

Am I correct in disagreeing with the "just make your rear end looser" approach?

MicVelo

Well, first thing to consider is "can you go to a different set of tires without a class bump?" If you can, then a square or less staggered set up (upping front tire width/softer compound/construction type) will reduce the understeer by increasing tire adhesion at the front; allowing the rear to slide out first. (But see next points)

As was mentioned in another thread here within last couple of days, it won't necessarily make your car go into "oversteer" mode as additional roll stiffness in the suspension at the rear (or less at the front but that defeats the purpose of increasing roll stiffness to achieve what you want it to do) may be needed to make the car truly oversteer. However, square setup will help to move the car to neutral with bias towards tail out happiness (oversteer).

That brings us to your question about increasing REAR roll stiffness to promote oversteer/minimize understeer.

The way to do this IS to increase rear roll stiffness through use of either/both stiffer springs/shocks (relative to front) and increased roll bar size or angle-of-attack (if you have adjustable bars).

The theory (and practice) is that whichever end you stiffen front or rear (more, relative to the other end), that's the end that's going to have the tires reaching their maximum slip angles first and once past the max angle, tires at that end get into "slide mode" (for want of a better expression). IOW, tail out first or over rotation is classic oversteer. (Or, if the front tires reach their max slip angles before the rear, the front will slide... the definition of understeer.)

I get what you're saying with the "weak arm analogy" but in practice, IF your bars are created equal (not stiffness, mind you, just that they're working OK in normal driving) then, adding stiffness to the rear isn't taking away traction from the front, it's adding stiffness to the rear.

Confused? OK, yeah, that was as clear as mud.... Using your analogy of a weaker arm.... it's not that you're taking any strength away from the one arm, you're just doing more reps with the other arm to make it stronger and the one that's just laying there while yer pumping iron doesn't increase or decrease it's strength.

Does that help your argument?

Phenom

iTrader: (4)

I'm still somewhat confused. Let's say my car currently understeers, and for the sake of argument let's assume that:

at 0.7 lateral G's = front breaks loose
at 0.9 lateral G's = rear breaks loose

If I wanted my car to be neutral, I'd want the front and rear to break loose at the same lateral G force. Increasing front tire size could then make my car look like this:

at 0.9 lateral G's = front breaks loose
at 0.9 lateral G's = rear breaks loose

But now if I were to adjust the sway bar in the rear to reduce understeer instead of increasing front tire size, we know the front will break loose roughly at the same G force as when I started. So assuming we stiffen the rear enough to attain neutral handling, my car will look something like:

at 0.7 lateral G's = front breaks loose
at 0.7 lateral G's = rear breaks loose

So if that's all logically sound, it seems (to me at least) that stiffening one end (ie making it less grippy) only makes that end crappier in order to match up with the crappy front. They'll be roughly even and neutral, but what good is neutral if they're both crappy? On the other hand, rather than bring the grippy side down to match the crappy side, you can bring the crappy side up to match the grippy side. That way it'll be neutral and grippy all around.

That's the theory aspect of it that I'm hung up on. Am I making sense?