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Widest set up for stock 18 inch rims

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Old Dec 25, 2015 | 09:13 PM
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Default Widest set up for stock 18 inch rims

I heard it was 245-40-18f 265-40-18r just wondering what's the widest you can go on stock 18.
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Old Dec 25, 2015 | 10:22 PM
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Two things, first there are 3 different versions of stock 18 inch wheels, 1 of the sets is a bit narrow to run a 265 on.

Best thing to do with stock wheels , replace them. A bit narrow
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Old Dec 25, 2015 | 10:35 PM
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Default K

Originally Posted by terrasmak
Two things, first there are 3 different versions of stock 18 inch wheels, 1 of the sets is a bit narrow to run a 265 on.

Best thing to do with stock wheels , replace them. A bit narrow
Don't have the money this year to buy aftermarket rims but anyways I have a base 06 model if that helps a bit with what your talking about. So that's a 18-8.5 not sure if that's all four corners.

Last edited by Ray8674; Dec 25, 2015 at 10:38 PM.
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Old Dec 25, 2015 | 10:37 PM
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Originally Posted by Ray8674
Don't have the money this year to buy aftermarket rims but anyways I have a base 06 model if that helps a bit with what your talking about.
No!
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Old Dec 25, 2015 | 10:43 PM
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so what set up would you recommend?
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Old Dec 25, 2015 | 10:44 PM
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So you have an 8 inch front and 8.5 rear.

245/40-18 front and 265/40-18 rear will work

I would do a 245/40-18 front and 245/45-18 rear, just for a better handling setup.
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Old Dec 26, 2015 | 04:25 AM
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It depends on the brand and model of tires you plan to use. Check the tire manufacturer's web site for recommendations on the minimum, optimum and maximum wheel widths for the tires you plan to use.
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Old Dec 26, 2015 | 07:20 AM
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Quality is more important than width, a proper fitting tire to the wheel is more important than width
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Old Dec 26, 2015 | 07:35 AM
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Originally Posted by terrasmak
So you have an 8 inch front and 8.5 rear.

245/40-18 front and 265/40-18 rear will work

I would do a 245/40-18 front and 245/45-18 rear, just for a better handling setup.
Originally Posted by terrasmak
Quality is more important than width, a proper fitting tire to the wheel is more important than width

Agree with T'smak again.....

Stick to the old "1.2 Rule"; that is, tire width not to exceed 1.2x the rim width and you'll be safe. (That's approximate and has some latitude in it... 1.15 to 1.25 or so is fine.)

Physically, you can run a tire fatter (or skinnier.... stretched) than that but at 1.2 (or 120%), you hit a point of diminishing returns - where performance drops off - due to contact patch squirm and excessive sidewall flex. Anything wider, you might as well have run a taller aspect ratio.

Example: For 8.5" wheel.... 8.5 x 1.2 = 10.2" tire width (or 259.08mm); hence Terrasmak's replay stating a 265 will work is correct.

To repeat, you can run a larger tire PHYSICALLY but there's no point.
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Old Dec 26, 2015 | 11:51 AM
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Don't tell amature drivers to run a square set up on a sports car. I'm assuming its new to him and you want him to go square so it will just come out from under him while hes exploring the car?
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Old Dec 26, 2015 | 12:01 PM
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Originally Posted by NiLL
Don't tell amature drivers to run a square set up on a sports car. I'm assuming its new to him and you want him to go square so it will just come out from under him while hes exploring the car?
no one is telling him he should run sqaure, terra said that HE personally would, and so would i and many other drivers. infact, out of all 4 set of wheels i have, only 1 set is a stagger set up.

squares are better for handling that is a fact. 245 all the way around is going to be better than 225f 245r.
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Old Dec 26, 2015 | 12:44 PM
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It's better for handling when you know what you are doing. So what happens when he takes it to the limit and instead of a bit of understeer letting him know he needs to slowdown, he just slides off the road? there is a reason that isn't put on production cars.
AND if he is new to the Z, and doesn't know the handling 100% yet, you are setting him up for a wrecked car.
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Old Dec 26, 2015 | 01:01 PM
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Originally Posted by NiLL
It's better for handling when you know what you are doing. So what happens when he takes it to the limit and instead of a bit of understeer letting him know he needs to slowdown, he just slides off the road? there is a reason that isn't put on production cars.
AND if he is new to the Z, and doesn't know the handling 100% yet, you are setting him up for a wrecked car.
Cause is stock form it understeers badly , with a square setup is still is an understeer car. It takes a lot of work to make a Z neutral
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Old Dec 26, 2015 | 01:38 PM
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Originally Posted by NiLL
It's better for handling when you know what you are doing. So what happens when he takes it to the limit and instead of a bit of understeer letting him know he needs to slowdown, he just slides off the road? there is a reason that isn't put on production cars.
AND if he is new to the Z, and doesn't know the handling 100% yet, you are setting him up for a wrecked car.
first, he wouldnt be able to push the car to the limit if he doesnt know how to correct himself if something goes bad. 99% of the population cant push their cars to the limit.

secondly, he shouldnt be pushing his car to the limit on public road in the first place. save it for the track.

thirdly, assuming he CAN push his car to the limit, oversteer is still better than understeer, any decent driver knows that.

fourthly, like terra says, these cars are pretty hard to set up for a balance drive. so i highly doubt that he will be oversteering anytime.
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Old Dec 26, 2015 | 06:40 PM
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I searched for other opinions after reading this thread, and I see that Terrasmak has been consistently recommending the the 245/40 F and 245/45 R sizes for many years. I will go with those for my next tire setup (on some RE-71Rs).
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Old Dec 26, 2015 | 07:25 PM
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Originally Posted by sauer420
I searched for other opinions after reading this thread, and I see that Terrasmak has been consistently recommending the the 245/40 F and 245/45 R sizes for many years. I will go with those for my next tire setup (on some RE-71Rs).
It's a fun combo , I ran it on my 05. Great balance, much more fun to drive , it actually had front grip. Last, it was my wife's daily driver, I wouldn't have done it on her car if it was dangerous
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Old Dec 27, 2015 | 03:17 PM
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I ran 245/40 front 245/45 rear on my last 2 setups. I could of gone wider with a 9.5" wide wheel but these tires were brand new. Slight stretch but like terrasmak said it felt more balanced. Which is why i run squared setups. ARP extended studs in the rear for my eibach 10mm spacer to make the rears match fitment up front.

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Old Dec 29, 2015 | 02:09 PM
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I really liked my 245/40-18" (f) x 245/45-18" (r) setup. It was very neutral and a fun drive.

I purchased new wheels and switched to 245/40-18" (f) X 275/40-18" (R) and am unhappy with the handling. There is way too much "plowing" and understeer wit this setup.
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Old Dec 29, 2015 | 02:58 PM
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I first got the car with the stock 225/45R/18 - 245/45R/18 setup.

Then ran 245/40-18 - 245/45-18 for a few months.

Now I'm running 245/40-18 - 265/40-18.

All tires were semi-new or brand new Michelin Pilot Super Sports.

I have to say for handling SPECIFICALLY the square setup did feel the best. Least amount of plowing, best turn-in from center feel, also the car felt a little less grabby changing lanes on the interstate and stuff.

The reason I upgraded to the 265 rears was because I thought the 245 was just a little small if you plan to add any power (maybe it has something to do with being an open diff still?)

The car understeers a bit more than the square setup, but negligible when compared to the stock stagger. Also worth noting- when letting the wheel return to center with the stock and square setup, you could pretty much let go of the wheel and it'd track straight. With the 245/265 setup if you leave it slightly off center it will continue to track that way and requires a little effort to get it straight again. It's hard to explain- I'm sure people with more experience know what I'm talking about and have a name for it. I just attributed it to having more rubber on the road.

With all that being said, when trying to put power down it's a lot easier with the 265's. I plan to do some bolt-ons and tune in the future and definitely wouldn't want to stick with the 245's. I think I could probably get away with leaving the 8.5"/265 setup alone for a while and not have the rear end try to step out on me as much.

Just a regular guy... my .02
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Old Dec 29, 2015 | 07:10 PM
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Originally Posted by Spike100
I really liked my 245/40-18" (f) x 245/45-18" (r) setup. It was very neutral and a fun drive.

I purchased new wheels and switched to 245/40-18" (f) X 275/40-18" (R) and am unhappy with the handling. There is way too much "plowing" and understeer wit this setup.
Moving to a larger rear contact patch (stagger) while maintaining a consistent front patch almost always results in increased understeer because slip angles are increased and the rears not "allowed" to reach max slip angle before the front - a condition required for oversteer.

But keeping a larger contact patch overall increases overall grip so it's a tradeoff when you depend on ONLY tires to tune with.

Going to a larger rear contact patch REQUIRES one to increase rear roll stiffness (via sway bar adjustment and/or corner weighting) to decrease the understeer (increase oversteer). Such roll stiffness allows the tires to reach max slip angle faster and thereby allowing the rears to "break traction".

Always a tradeoff, no matter what one does to "make it handle better". Just make sure you do the proper combination.
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