chrisjersey06

iTrader: (35)

I have a question for anyone who knows about tire setups. I have the stock 18's on my car, with the stock tire sizes (225/45/18, 245/45/18) and I know that the exact plus sizing is 245/40/18 and 275/40/18, but will there be any adverse effects by only increasing the rears and leaving the fronts stock? I have stock sizes on my car right now, but have brand new Nitto NT555's in 225/45/18 up front, while the rears are stock sized Goodyears. I want to get the same Nittos for the rear, but the only size they come in that I will be able to use back there is 275/40/18.

I know that by increasing the front tire size (235 or 245) that it reduced understeer. But what would happen if I left the fronts 225 but got 275's for the rear? Would that increase understeer? Be dangerous? Or is that okay? I know that going wider is better, but it seems that 225-275 is a big difference.

Let me know your guy's opinions on that setup. Thanks

Chris

davidv

iTrader: (2)

Difference in overall tires height is 17.5 mm. That’s OK.

For width would I run a difference of 50 mm? No.

Plus Nitto makes crummy tires.

ThE_JacO

Fresh 275 in the back with more treadworn 225 in the front is pretty much a surefire recipe for under-steering or introducing uncontrolled drift and sway.
Might be fun in a parking lot or on some autoX, but I wouldn't want to drive that regularly or track it.

Plus 275 on stock 18/8 is a pretty bad idea. Of course somebody will come up and say it's perfectly possible and that they do it all the time and have no problems with it, but that doesn't mean they're not half or entirely full of it

If you don't want to change wheels and/or go into an understeer fest get 245 in the back tops.

Edit: Tarded out typing the post at 2am while packing. Yes, I did mean understeer, thanks for the poke Zenophile.

350Zenophile

iTrader: (20)

I think you mean understeer Jaco. The proposed setup would understeer like a ****. Otherwise I agree with your comment about a 275/40 on an 8" wheel being a bad idea.

davidv

iTrader: (2)

My bad. I did not realize that the OP was attempting to put a 275 mm tire on a 8.0 inch wheel. No no not me.

terrasmak

iTrader: (8)

I did that combo for about 2 months , but with the proper size wheels for the tires. VDC didn't like it, not for the size, but the front end would push pretty dam easy. Just a normal freeway onramp and VDC would trip.

chrisjersey06

iTrader: (35)

Thanks for all the input guys. Didn't know a 275 was to big for the rim. I figured it would be okay since that is the reccomended upgrade size for a 245/45/18, and because this guy did it with the same wheels/tires:

https://my350z.com/forum/wheels-and-...stock-18s.html

But after hearing what you all had to say, I won't be doing it. I'll just stick to a 245/45, or maybe a 255/40? Or is anything but stock size going to induce understeer. I'm looking for more traction in turns.

Another question, anything bad about running different front and rear tires? Right now I have the NT555's on the front (just bought them, still need to mount), but they don't come in any size for the rears, so I'll need to go with a different tire when the time comes.

davidv- Why do you say the Nittos are crummy? Any experience with them? I bought them based on good reviews from 350Z owners.


Chris

WhiskeyHotel

iTrader: (5)

If you want a more neutral or balanced Z, stay with a square setup. For 8's that would be 245/40 f and 245/45 r (to keep the TCS happy). Add a stiffer anti-roll bar in the front.

Check out this article in Modified Mag:
http://www.modified.com/projectcars/...t_2/index.html

Spike100

You can mix different brands of tires, front-to-rear. I’ve done this successfully. Here are some points when doing this:

• Stay within the same class of tire. In other words, if you have summer performance tires on the rear, go with that class on the front. You don’t want to mix something like all-season tires with maximum performance summer tires.
  
  
• Avoid mixing tires with rigid sidewalls and flexible sidewalls. I did this (mounted front OEM Bridgestones, that are relatively stiff, along with rear Goodyear Eagle F1 GS-D3, that have soft sidewalls), and the result was not good. The handling felt wiggly because the front or rear was stiff, and the other end was flexible.
  
  
• I don’t have personal experience mixing unidirectional tires with bidirectional tires. Hopefully another member can offer a comment about this setup.

When mixing different brands front-to-rear, it’s possible that you could end up with a bad match, and the only fix is to buy another set of tires.

--Spike

ThE_JacO

You can with most tyres. Tyres, especially with tall and soft enough sidewalls will fit on pretty much anything, that doesn't mean that it's a good idea
275 width tyres on an 8" wide wheel means they will bulge a lot, have a less than ideal contact making some patterns less effective than the manufacturer intended them to be, and have terrible sidewall behaviour and radial distribution.

Traction comes first and foremost from the compound.
A top quality sticky summer tyre in 235 will run circles around a bad 275 on the wrong wheel any day of the year.
More traction in turns also isn't just a matter of width. Stiff sidewalls, square shoulder, sticky compound, patterning, quality of the asphalt and a number of other things all come into play before the width alone can make much difference (of course more width with the same compound will stick better).
There's also other qualities to a tyre that you might or might not judge important for going hard into a turn. How much feeling for contact you have, how progressive the acoustic warning is (how long before actually loosing considerable amount of adherence the tyre starts whistling) and all these things. Those are also largely affected by sidewall qualities and compound.

Maybe you should go into details about what behaviour of the Z you don't like and in what cases. Chances are better tyres, a couple driving tips and a lesson or two in sports or defensive driving will get you what you want before you have to change wheels and widths
If you want tighter turns then you'd probably want to square your setup rather than making the rear wider (and deal with fishtailing a bit on wet whichever merry way you feel)

As for understeer, with the upgrade you mention it would be induced by the difference between F/R wheels.
The simplistic way to think about is: More contact and stickyness in the back and less in the front means that the back will tend to push the car straight.
To prevent that you'd need to introduce more glue in the front, not in the back.

A certain amount of understeer is usually what car manufacturers want, since it's less dangerous and more controllable for your average joe than oversteering.
The Z, for its class, is considered a very controllable car with just the right amount of understeer for the setup it runs (a little bit too much according to somebody).
Some people like it, some people find it excessive and either run square setups, or close to square, or slightly tweak suspensions to let the car lean in more or less and introduce more under/over steer.
anyway, you probably don't want MORE understeer than it already has, which means you should forget about runnin 225/275

You can run different tyres F/R, but it's the same of changing stagger, different suspension settings etc.
You introduce one more variable in figuring out how the car will handle, and if for something like suspensions you can experiment with settings quite cheaply and efficiently, for tyres it's not as cheap or quick for obvious reasons.
If you want to mix you'd better make sure you know what mixing those specific tyres will do, it might be what you're after, it might be the opposite.

Spike100

^^ Wow! Great post and information.

And...Great writing style (clear, concise, and articulate).

--Spike

WhiskeyHotel

iTrader: (5)

Yeah, I wish I had said that.

davidv

iTrader: (2)

Here is what I often see members do: go from a 235 mm to a 255 mm tire for an additional 20 mm. Cool. But to save money they get a mediocre 255 mm tire. Not smart. A good 235 mm tire will outperform a mediocre 255 mm tire any day.

Before buying tires check these test results: https://my350z.com/forum/showthread....ighlight=tires

davidv

iTrader: (2)

Yes I have mixed tires for autocross. Sometimes I have been pleased with the results. Sometimes I wonder what the hell I just did. Since I don't carry tires with me the solution is just common sense: adjust your driving style.

Spike100

Oh no... not that again.

Just kidding of course, but the first message on this thread has an old chart (listing products, some which are now discontinued), and its information is arguable. The thread evolves, describing changes and new products, but it degenerates into owner opinions that are not necessarily accurate or helpful.

I really think that a Moderator should lock that thread (designating it as historical data), and invite someone to start a current version (which of course will by its nature have a limited life).

--Spike

chrisjersey06

iTrader: (35)

Wow, thanks guys. GREAT information!!! It is definitely going to help me a lot for the near future.

I got my new tires mounted today. So my current setup is 225/45/18 Nitto NT555's in the front and 245/45/18 Goodyear Eagle F1 GS-II's in the rear (with plenty of tread left). I haven't done anything crazy yet, but on a little 20 minute spirited drive, it feels to handle much better than my previous setup, which was BFGoodrich G-Force KDW2's in 245/45/18 in the front (Same size front and rear). My main mistake in that setup was the wrong sized sidewall for them, I think that if I had 245/40/18 for the fronts it would have been much better. But so far I'm like the Nitto's a lot more than the BFG's in the dry. I hear the Nittos are trash in the wet though because its more a track tire, by some reviews that I've read on them.

So last question, when I replace my rears I should stay with stock size correct? Or is there anything better I should try out?

I would, but I think the main things I don't like are due to my lack of any suspension mods. So I don't want to say what I want to change about it when I know the solution. There are 30mm rear spacers, springs, and sway bars in my near future. The spacers and springs are mainly for cosmetic purposes, but I hear the sways are a major improvement, especially for 03 guys (I think the OEM front one was beefed up in later years). I created this thread to try and find a good tire setup to compliment my future (yet simple) plans. My car isn't a daily driver, but its not a track car either. I don't auto-x, do track days, or anything competitive honestly. I enjoy taking it out on back roads on nice days, so my needs are fairly simple, the Z handles great right out of the box (I had a couple of 300ZX TT's, a 93 and 94, and those things are boats, even with suspenion mods.) Your post was very helpful and informative. Thank you!!

Chris

terrasmak

iTrader: (8)

For us 03 guys , well sways help all years, but the main one is the springs and shocks. 04.5 and newer spring and shocks are so much better. Cheap solution get 04.5 and newer shocks and springs, but since you want the car lowered get Cobb springs. You will need/want the newer shocks or a good set of shocks(d specs) with this setup.

Cobb also has a set of sways, i would suggest them to go with there springs.

If you plan to change wheels, don't bother with spacers. Waste of $$$

Spike100

^^ What is your opinion on the Nismo setup?

(I have no idea, and that's why I'm asking. I'm guessing it's overly expensive though.)

--Spike

bballgms

i would change the back from a 245 to a 255 or maybe a 265. if u go wider u creat understeer.

chrisjersey06

iTrader: (35)

Yea I want to lower it a little, but nothing crazy. an inch at the most. I was thinking about some Tein S-techs, Tokico Blues, and Hotchkis sways, but nothing is final quite yet. I don't need the adjustability of D-specs or Konis.

and about wheels...I honestly can't see myself changing them anytime soon. I love the look of flush stockers from pictures of other members cars with them. I'm not looking to be bling-tastic, or show-off either. The only wheels that I could see myself getting are $1500+ and that's not even a lot, but to much IMO for something cosmetic. I can personally find better things to buy for this car with that much money.

I spent over $3k on wheels for my last car, and they looked great, but then I realized how much other stuff I could have had instead of them, and when I wish I had done so, they weren't worth half that when I tried selling them, and only ended up getting $1000 with tires after having the ad up for over a month. Bad investment, and didn't really improve anything about the car other than the looks.