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Discussion Starter #1
So why is the front tires smaller than the back tires on a Z? Also, if I wanted a "regular" tire for my spare instead of the donut that usually comes with a car, would I use the smaller front tire or the larger back tire?

Thanks guys.
 

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I believe it is to produce understeer which is a safer for the average joe. With a smaller (narrower) front tire, you make the car a little easier to control.

As for the full size spare, it will not fit in the trunk.
 

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I've been asking that question myself! :)

Put another way, the wider rear tire has a bit more grip than the front. This helps to prevent oversteer.

Toykilla is right. A full-size spare would not fit in the trunk where the "donut" spare resides. If you carried a full-size spare, you would be better off with the smaller size tire (225) rather than the other (245).

When my Nittos wear out, I'm going to 245's all the way around.


All best,
Joe
 

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Discussion Starter #4
As for the full size spare, it will not fit in the trunk.
Oh my gosh, that's retarded? Who designed the spare tire space?

Don't they know many of us would prefer a "real" tire as opposed to a donut?

By the way, what's UNDERSTEER?
 

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ToyKilla is correct. By making the front tire tread width more narrow than the rear tread width the car will tend to understeer. Cars that exhibit understeer tend to make the legal departments happy.

When I upgraded wheels and tires I went with equal tread widths; 245/40-18 on the front and 245/45-18 rear. This combination reduced the understeer.
 

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Let me ask this dumb question. If the tire sizes are different and I go to a tire shop, how would they rotate my tires? Are tires rotated from back to front or side to side? Seems like back to front.
 

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Let me ask this dumb question. If the tire sizes are different and I go to a tire shop, how would they rotate my tires? Are tires rotated from back to front or side to side? Seems like back to front.
With staggered tired they can only rotate side-to-side, not front to back, so that's all they will do (all they better do).

My Z also came with "asymmetrical" tread... meaning they're supposed to turn in a certain direction.

So basically I can't rotate my tires at all! Or at least not without removing the tire from the wheel.
 

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Oh my gosh, that's retarded? Who designed the spare tire space?

Don't they know many of us would prefer a "real" tire as opposed to a donut?

By the way, what's UNDERSTEER?
When you head into a turn, the front and rear tires are thinking about different things...

If the rear tires start to lose grip (approach their "traction limit") first, then the back end wants to make the turn wider than the front of the car. So the effect is the car makes the turn more sharply than intended. That is oversteer.

If the front tires start to lose grip first, then the front makes a wider turn than the rear, so the car makes a wider turn than intended. That is understeer.

In an oversteer situation, the turn becomes sharper, so it makes the traction even worse in the back. So if the driver doesn't compensate, you end up with the back end sliding out and you're now you're in a skid.

In an understeer situation, the process is more self-regulating. The car is turning less, so more traction is available, and the car remains stable. You turned a lot wider than you expected, but you didn't lose control. (And hopefully didn't plow into the guard rail.)

That's why most cars are made to understeer. It's safer. It's also why the legal/insurance guys prefer understeer. It's also why performance drivers dislike it.
 

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Oh my gosh, that's retarded? Who designed the spare tire space?

Don't they know many of us would prefer a "real" tire as opposed to a donut?

Well, most (if not all) auto manufacturers provide a "donut" spare. This greatly reduces cost and weight, and gives us a little more room in the rear cargo area.

That area is small enough as it is! :lol:



All best,
Joe
 

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With staggered tired they can only rotate side-to-side, not front to back, so that's all they will do (all they better do).

My Z also came with "asymmetrical" tread... meaning they're supposed to turn in a certain direction.

So basically I can't rotate my tires at all! Or at least not without removing the tire from the wheel.
Unidirectional tires. You can swap them side to side but the tires will have to come off the rims.....
 

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...which is what I do. I run the same sized tire all round, but because they're directional and my rim sizes are staggered I have to strip and refit.


You can produce understeer by suspension setup, and the Z doesn't make enough power to require a wider rear rim (its not exactly a Viper or Ferrari), so I'd say it was a marketing ploy. Everyone knows sports cars have fat rear tires, to hold back the horses.

If you bypass the cynicism and give Nissan credit, you could say that its to help enthusiasts. By not having the suspension set up to understeer so much, you sell the car to your average idiot, who leaves it stock, in a safe understeery feeling...but your mod-willing guy can go to the same sized tire all round and make the car more neutral without having to splash out on suspension parts.

If you see the review of the S2 Elise on Top Gear, when they pulled Lotus' test driver in because Clarkson couldn't powerslide it, you'll see that since the S2 was getting sold in more markets (namely the US, hi guys!) they had to make the car less pointy and enthusiast and to suit a wider range of drivers. As a result, the staggered sizes and the terminal understeer.

Luckily for the Poms, a different neutral setup is a factory option.
 

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One of the first things Sport Compact Car magazine did with their 350Z was to replace the rims and fit 275/40 tires all around. Right now, I'm running 245/40's up front and 275/40's out back. My next set of tires are going to be 255/40's up front and 265/40's out back. This will make them closer to the same size without me having to get new rims.
 

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This may be a dumb question but aren't the front and rear OEM rim size for the 2006 the same? The only difference is the actual tire size front and rear? I mean, basically the rim without the tire is the same right? If yes, then I can put the same size tires all around if I wanted to?

Rajan
 

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As far as I know, only the Track model uses different sized WHEELS front and back.

If the wheels are the same diameter, you can use the same tire size tires all around.



All best,
Joe
 

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Unidirectional tires. You can swap them side to side but the tires will have to come off the rims.....
For some reason I got it in my head that asymmetrical = unidirectional! But I guess that's not true. Learn something new every day. :)
 

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As far as I know, only the Track model uses different sized WHEELS front and back.

If the wheels are the same diameter, you can use the same tire size tires all around.
All best,
Joe

The base model through the touring model have the same diameter rims, but they are different widths. The front rims are 8" wide and the rear rims are 8.5" wide. You can mount the same tire that's on the rear rims on the stock front rims without any negative effects. Here is a good tire size calculator: http://www.1010tires.com/TireSizeCalculator.asp
 

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So why is the front tires smaller than the back tires on a Z? Also, if I wanted a "regular" tire for my spare instead of the donut that usually comes with a car, would I use the smaller front tire or the larger back tire?

Thanks guys.
Just got my 05, it has a full size spare (rear even) fully inflated, its a bit tall in the back, doesnt fit together like it should, but it fits, mats cover it
 
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