370z MEATY TIRE THREAD

[VinceThe1]

Originally Posted by jofro6

Does that push the car at all with 12" wheels in the back? What size front width are you running? Im torn this winter between doing an 11" or 12" setup in the back. I dont really want to run cambered at all and am trying to keep it all inside the fender with no poke as well.

What do you mean by "push the car"

[jofro6]

push, like is there too much grip that it over powers the fronts more than normal with the comparative front to rear surface area of tire. I am probably not explaining it right, but Rust in the last post seams to understand what im talking about a bit

[VinceThe1]

Originally Posted by jofro6

push, like is there too much grip that it over powers the fronts more than normal with the comparative front to rear surface area of tire. I am probably not explaining it right, but Rust in the last post seams to understand what im talking about a bit

But see, there is two things, that a wider tire doesn't really give you a lot more surface area because what it gains in width it looses in length (contact patch).

Also, a larger contact patch does not immediately translate into more grip, because yes, you have more compound on the road to grip, but because the weight is distributed, it gips less per square inch, if you know what I mean.

Easy example, a with a tire that has 4 square inches of ground contact and that is loaded with 1000lbs of the car's weight, you would have 250lbs for every square inch of the contact patch, and the more weight you have on a point, the more grip you will have.

Let's say you install a tire with twice the contact area, at 8 square inches, with the same 1000lbs of car weight. Now, each square inch only has 125lbs to carry, so less weight per square inch = less grip...however, because there is more surface area, it compensates for that difference, in physics, in a perfect world, it amounts to the the exact same grip either way.

The reason I use wide tires is because I like the look, and because there is less stress on the wider tire, so it should last longer.

[Dcocci]

Originally Posted by jofro6

push, like is there too much grip that it over powers the fronts more than normal with the comparative front to rear surface area of tire. I am probably not explaining it right, but Rust in the last post seams to understand what im talking about a bit

understeer. Youre talking about understeer

[VinceThe1]

Yea as soon as he explained it, I understood what he meant...It's understeer under power, and that is usually mainly due to the car's weight distribution. Like a rear engine Porsche for example is very prone to "push" because there is a lot more weight at the back and that gives the rear of the car a lot of traction. When you hit the gas in a corner, that rear grip and acceleration makes the front wheels get light (like a loaded pickup truck behind it's rear axle, it wants to lift the front wheels off the ground), and that causes the front to plow as you loose a lot of traction in the front tires when you take the weight off of them.

I haven't noticed a lot of "push" in the Z with any tire setup I've had on, some road conditions may sometimes encourage it, but the Z is just generally a tail happy car

[jofro6]

Thanks for all the info guys. Definitely understand all the math parts (my major) you were explaining with per inch weight distribution and the understear. The only thing i dont grasp is the loss in length by going wider that you mentioned? maybe i just havent been awake long enough yet to see it though lol

edit: nevermind now i got it lol obvi the less per inch pressure doesnt cause the tire to flatten out as much shortening the contact patch.

[VinceThe1]

Originally Posted by jofro6

Thanks for all the info guys. Definitely understand all the math parts (my major) you were explaining with per inch weight distribution and the understear. The only thing i dont grasp is the loss in length by going wider that you mentioned? maybe i just havent been awake long enough yet to see it though lol

edit: nevermind now i got it lol obvi the less per inch pressure doesnt cause the tire to flatten out as much shortening the contact patch.

Exactly, so it really seems that there is no advantage to going with a wider tire, or a bigger wheel/lower profile tire setup, even tests proove that all they really do is add more weight...thus making the car slower and less fuel efficient.

However, the difference isn't really big and most of us do it for the look/stance of the car. The other advantage though is that because you have a wider tire, it has more surface area, so you need less pressure in your tire to hold the weight of the car vs a skinny tire, so you can run at 30-34psi instead of 35-38 like some do, and that will give you a larger contact patch with the road because the tire will flatten out better, which is good for saving your tire under wheelspin and overall wear...because less weight per square inch = less stress / less heat and overall less wear on the tire compound, it would also help on the track, since the wider tire would build heat slower than a skinny one, giving you overall better traction after a few laps, since the skinnier tire would already be overheating and possibly disintegrating, while the wide tire would last much longer under similar conditions, and wear less over time too.

[VinceThe1]

Attatched are two Images, the contact patch markings seen occured on my driveway after it rained.

These are from when I had my stock sized tires on my Nismo wheels, 245/40R19 front and 285/35R19 rear.

As you can see, the narrower front 245 tire has less width, but more length so that it looks more square.

The wider rear 285 tire has more width, but less length as it doesn't flatten as far due to the larger surface area it has it support it's given weight, and therefore looks like a rectangle. (granted, there is more weight on the front tires than the rears but I also run a few more psi in the front. I usually have them rear 34psi, front 36-37psi. Also, the car was on an uphill driveway with a small degree/angle, so there is a little more weight on the rear tires, and a little less weight on the front tires than usual)

[gussyturbo z]

IMG_3445.jpgIs this meaty enough? MT slicks on the rear and runners in the front.

[FPenvy]

Originally Posted by gussyturbo z

Attachment 95441Is this meaty enough? MT slicks on the rear and runners in the front.

i want them lol

[gussyturbo z]

Originally Posted by FPenvy

i want them lol

Man they hook up pretty nasty too!!

[Rusty]

Originally Posted by gussyturbo z

Attachment 95441Is this meaty enough? MT slicks on the rear and runners in the front.

Nice, but think you have to do something about the wheel lugs though.

[gussyturbo z]

Originally Posted by Rusty

Nice, but think you have to do something about the wheel lugs though.

Yea that's an old pic I have it studs now.

[FPenvy]

Originally Posted by gussyturbo z

Man they hook up pretty nasty too!!

im guessing base rear brakes though

[gussyturbo z]

Originally Posted by FPenvy

im guessing base rear brakes though

Yes base brakes. With stop tech rotors