Hey I'm a daily driver here in lynchburg, VA. I own a 2003 350Z track coupe. I drive basically to and from work and the thing I want to improve on most on my car is handling. Right now the thing I don't like about it is when I'm going through a sweeping curve hard, and the body leans a little bit, I don't feal like I have as much control. Now, that being said, I want a tire size on my stock 225/45R18 fronts and 245/45R18 rears that will give me more predictable (condfident) handling. I think what I want is more neutral handling (maybe a little oversteer but definitely no understeer) and from what i've read a non-staggered fit does that pretty well, for instance a 245/40 front and stock 245/45 rear. Now, given what i've said, is that the "recommended" size for what I want (on stock wheels of course, don't want to buy aftermarket)?

this article
http://www.mazda6tech.com/index.php?...d=20&Itemid=32
helped me but I'm still left with questions.

Also, what tire pressure should I put in my tires? more importantly, is it better to go on the low end (32 psi cold) or high end (40 psi cold)?

Thanks guys!

 

A set of adjustable swaybars will allow you to fine tuen your suspension much better than changing the tire size to try to eliminate oversteer/understeer tendencies. Try that first before changinge the tire sizes. Going to 245 width all around while keeping the stock height stagger will also help with the understeering, but will not allow for perfectly neutral handling because you won't be able to adjust it for your definition of "neutral handling". So at the very minimum, get a set of adjustable swaybars before messing with tire sizes, then get 245's all around if adjusting the swaybars doesn't get you to the level that you like

 

I'm gonna buy these for the same reason:

Hotchkis Swaybar
$299 shipped on the hotchkis sway bars. I have these instock (new models) and ready to ship.

Let me know if you have questions about anything at all.

If you are interested in making a purchase please paypal funds to sales@jscspeed.com (include “Attn: KSS” in the memo line) or call 215 643 5750 and ask for Kyle. Let me know if you need anything else.

Thanks
Kyle Shelley
JSC Speed
__________________
http://www.jscspeed.com/350z/350z_base.html

 

you should start with tires

staggered, non staggered - there is no right or wrong, despite what you read. Many out there prefer the staggered setup feel to non staggered. It's how you drive and what the rest of the setup looks like that determines overall handling.

 

Changing tires won’t do much for the “body-lean” you describe (you said: “Right now the thing I don't like about it is when I'm going through a sweeping curve hard, and the body leans a little bit…”). To improve this handling characteristic you would replace your OEM anti-sway/stabilizer bars with more rigid ones and probably replace your shocks and springs. You can buy these components from aftermarket suppliers or from Nissan (a Nismo kit consisting of sway bars, shocks, and springs that lowers your car about 0.5” and makes the car remain more flat in turns).

Under-steer is a handling characteristic where you feel the car is going too much forward as you turn hard. It feels as though it is “plowing.” If you feel the opposite front corner of the car from the direction of your turn (e.g., you are turning left and you feel the right front corner of your car dipping down), you might need a better anti-sway/stabilizer bar and probably better shocks and springs. In fact it could just be that your OEM shocks/springs are worn and need replacement (so you may want to check this first before upgrading to aftermarket suspension components).

Running all-square widths (i.e., 245/40-18” front and 245/45-18” rear) moves the car to more neutral-steer. I’ve been running this, and you certainly notice the difference. Handling is quite different. The caveat is simply that neutral-steer can quickly cross over to over-steer. Over-steer is something you don’t want; it’s dangerous. There’s a reason Nissan delivers the Z with a slight under-steer setup.

--Spike

EDIT: For tire pressures, stay close to 35 psi.

 

Slight , this car in stock form plows worse than a farm tractor.

 

That's sort of how I feel, but wasn't willing to state it quite that way for fear of flames and the requirement to answer many who may not agree.

Installing 245's on the front make the under-steer go away. With 245's on the front, you can do a staggered rear (Nismo like 275's on the rear) and you don't experience the under-steer.

--Spike

 

You should have just bought a Saab

 

275 tires all around, adjustable dampener and adjust the dampener until you get slight understeer..

 

Then attend autocross and HPDE.

Fix the driver first, then the car.

 

+1 , but sways help a lot . I did my first HPDE on stockers and it felt good , i did the second on Hotchkis and it felt planted.

 

+1 this is the cheapest and best way. Get new springs and dampers or coilovers first, then fine tune with sway bars.

 

You don't want "NO UNDERSTEER." You want slight understeer, or maybe neutral. You certainly don't want oversteer on a street car.

 

I have a great car. 245/40/18's all around, zeal coilovers lowered 1.5 inches, set at 1.5 degrees camber. Cusco front and rear sways. Cusco front a-arms, and Battleversion rear arms. Car is extremely neutral, and predictable.

 

I disagree. Understeer scares me.

 

finally the voice of reason!

Tires don't change body roll much? Wow....ok (that advice is wrong by the way). Anything that changes the roll center of the car changes body lean characteristics. Maybe switching from one all season tire to another won't alter roll characterisitcs much, or changing from one snow tire to another won't, but changing among true performance tires, absolutely, without question, can alter body lean characteristics, and often by a significant amount. Tire changes accomplish this, springs accomplish this, sways accomplish this, alignment accomplishes this. All of these factors play together to form overall "feel". Suggesting otherwise is poor advice.

Don't automatically go to the "no staggered" setup - setups can vary in their specs and there is no such thing as a magic recipe. There are variations and they all depend on many factors, not the least of which is the DRIVER. You, ultimately via your driving style, have control over what the car does. Want a front wheel drive car to drift? It can certainly be done. This is why David's suggestion is the best one. Fix YOU first, concentrate on the car when the you are more capable than it. Right now, it is more capable than you (and not just you, than most)

I've run the staggered setup on my car...I would never do it again. The car wasn't as fun, and I wasn't as quick. But that's me and YMMV.

Performance parts are great - they are fun to buy, fun to install and fun to play with (when you get the right stuff). But all the parts in the world don't make a competant car. They certainly don't make a fast car, or a good handling car. The right driver, with the right advice, and the proper setup by someone who understands physics and the dynamics of handling changes, is what makes a competant car (like a Z is in stock form) to an exceptional car.

 

well...it's supposed to.

And it isn't so much that oversteer is anymore dangerous than understeer, it is just way easier to learn how to compensate for understeer.

 

Have a drive in an old 911 and see if you prefere oversteer

 

lol. porsche's are weird monsters that I have no intentions of driving again!

 

You remember. Everyone raved about the great handling; but the truth was that all that rear engine weight extending beyond the rear drive wheels provided some scary experiences. The car felt as though it was neutral, but in fact it was super over-steer. The Porsche 911 I was driving in 1973 over-steered so excessively that even applying the brakes hard with a slight wheel turn (to avoid something ahead) could put you into a sideways drift, or worse. A hard turn (especially on a wet roadway) could suddenly cause a rotation where recovery was nearly impossible. If I recall correctly (35 years ago is a long time for my feeble memory), the car didn’t have a rear sway bar (or if it did, it was flimsy). There were a lot of aftermarket racing parts for this car to make it track worthy, and adding a rear sway bar to the car did make a big difference. But, it was still tricky to the point of being dangerous.

The Z is just a great handling car.

--Spike