LiL BenNy

what kind of rims are you rocking (brand size et) and what rubbas ya using?

Kane

iTrader: (1)

huh? Why does turbo matter?

19 by 9.5 +28 offset with fenders rolled in rear with 245/30ZR19
19 by 18.5 in the fronts with 225/30ZR19

There are some pics in my other posts, but I am too lazy to link them, you can look them up if you wanna see.

LiL BenNy

turbo = more power to the wheels... seeing who got wider rims/ tires etc...

mysql101

i've been running 245/35/19 for a long time. When my tires run out, I'm going to go back to 18" rims, tire width will be the same or slightly wider... but that's going to be 20k miles from now.

LabDad

Lot of N/A guys running around w/ 9.5" wide wheels.

LiL BenNy

dagg, im having a hard time finding affordable rims in the sizes i want that dont look like crap... anyone have suggestions for a 18x9 rims prefferably bronze or polish black or polish black with chrome lip...?

chrism

how about a nice set of VORK's?

LiL BenNy

bootleg volks? only if that add more ricer points for mee

LabDad

What do you consider affordable? Gruppe-S has some 18x8.5" Forged Rays 57F wheels on special. Bronze, gold, gunmetal are ~$1,200, black w/ red or blue edge are ~$1,300. I think those prices include shipping in the continental US.

Enkei RPF1s in 18x9.5" sizes are available for $300/wheel from a couple places.

http://www.gruppe-s.com/
https://www.rx8club.com/auto-rnd-91/killer-special-enkei-rpf1-18x9-5-45-a-98939/
http://www.good-win-racing.com/Mazda...els-Tires.html

chrism

benny wants to pay 300 for the set of wheels (shipped)

smrx8

iTrader: (1)

Then he aint getting nothing but junk yard wheels I would sale you my rims but there silver w/chrome

TurboEight

iTrader: (1)

i m running stocks...lol...garbage....

potenza=****

going to get some new tires...but will be running 245 on the stock wheels...

SC-ed

These are good and cheap:
http://cgi.ebay.com/ebaymotors/18-Gu...QQcmdZViewItem

TurboEight

iTrader: (1)

look at the diff...

lol....from a 350z then he put a pic of that integra, should never have done that.

StewyRX8

Couldnt agree more about the potenzas...

LionZoo

So I have a question that I've been trying to answer. As we know, wider tires don't make the contact patch bigger, just wider which benefits cornering. However, for more grip during acceleration we should have a patch that's longer as a longer patch promotes more longitudinal grip. Obviously this can't be taken to the extreme, but if you look at pictures of Top Fuel dragsters their rear tires aren't that wide. Therefore, why do people insist on wider tires when their power goes up? Granted if you factor in acceleration out of corners when the tires are cornering at 0.5 g as well as accelerating outward it makes a bit more sense, but people say that turbo'd RX-8s need wider tires to "hook up" on the strip. Shouldn't it be the opposite?

ChrisRX8PR

iTrader: (1)

Hello,
I have a good answer to your question. First I must mention something that might make you think about this matter a little bit: If using wider rubber doesnt increase the ability to tranfer power to the ground then technically you could have a Carrera GT with 175/70-14 tires from a corolla(which would be more desirable for fuel economy purposes, i.e thinner tire = less friction) and it would still tranfer the power correctly as long as it wasnt cornering. Obviously this is not the case. However you are right about what you stated. IN THEORY the contact patch of a tire is a line(you are 100% correct about this). This line has zero width therefore it has zero area and if you make it longer(wider tires) or shorter(thinner tires) its area remains unchanged. But this is in theory, in reallity we have whats called elastic deformation. Which simply means that because the tire is soft(rubber) it deforms when it comes in contact with the road creating a contact patch that does have an area and looks like a rectangle not a line. If you increase the lengh of this contact patch(wider tires) the contact area increases and you have more area gripping the ground. The increase in grip is comparable to wearing a big soled sneaker on a polished flor vs wearing a women's high heel with a smaller contact patch at the bottom. If the woman wanted to start running suddenly she would slip misserably before attaining any speed but the man with the sneakers would accelerate effortlessly due to his increased grip. Same applies to a car. Obviously tire compound has a huge effect on this as well because a 2 inch wide rubber tire would grip mroe than a 10" wide hard plastic one but since your question was regarding tire width then we are assuming that it is the same make, model and compound tire but in different widths. I hope this helps answer your question effectively, it took me like a year to fully understand this grip deal when I was in college, jeje.

Chris...Esmeril

LionZoo

Actually you're mistaken. I stated that the contact patch is an area, but when you go to wider tires the contact patch area doesn't not change, it merely changes the shape of the contact patch. With a thin tire, say the 175 in your example, the contact patch might be a rectangle that is long lengthwise. However, if you then change that tire to something like a 305, the rectangle that is the contact patch changes shape to become wider, but shorter in length. However, the AREA is the same since the area depends on the normal force (weight of the car) and the inflation pressure of the tire. You want a longer distance for the contact patch in the direction of acceleration since the acceleration force is then resisted with a smaller slip angle which generates more grip. For cornering, that's widthwise, but in terms of acceleration that should be lengthwise.

SC-ed

Hows that 175 and 305 areas are same?
I think your logic is wrong.
Contact patch is a contact patch no matter what direction.

LionZoo

http://www.carbibles.com/tyre_bible.html

Scroll down, and go to "Fat or thin? The question of contact patches and grip." I'm trying to be very nice, but people are trying to argue with me with faulty logic about wide tires. Every automotive engineer knows that contact patch AREA isn't increased with wider tires.

SC-ed

Well it sounds about right but I still can't believe nothing is changing.
Why they go wide on race cars?

LionZoo

You want a longer distance for the contact patch in the direction of acceleration since the acceleration force is then resisted with a smaller slip angle which generates more grip. For racecars, cornering quickly is the key, which means maximum lateral acceleration. To achieve that, you want a long distance for the contact patch in the lateral or side to side direction of the car, in other words a wider tire. Unfortunately, for acceleration a wider contact patch shouldn't help.

The deal with slip angles is basically the smaller the slip angle for a given lateral acceleration, the more potential the tire has left for grip. Different tire models don't have the same slip angles for the same lateral acceleration nor do all tires "slide" at the same slip angle. In fact, Formula 1 tires have extremely small slip angles per unit of lateral g and also slide at a small angle; that's why they're so twitchy and hard to drive. A tire with bigger slip angles per unit of lateral g tends to communicate better about its limit as there is a noticeable fall off in steering response at the limit.

SC-ed

So for the 8 wider is better. We don't have torque but can corner even better.

LionZoo

Until the added weight from the wider tire bogs your acceleration down even further and you can't launch out of corners. Remember, exit speed is key on a racetrack; a higher apex speed generally leads to a higher exit speed, but raw acceleration down the resulting straight is also important.

Now you see why tire selection has been driving me absolutely crazy for the past month. There are so many factors and tradeoffs to consider.

ChrisRX8PR

iTrader: (1)

LionZoo,
You are absolutely right about the fact that if you keep the weight the same and increase the size of the tire it will deform a little less because it is a wider tire and the weight is distributed alond a wider surface therefore the width of the contact patch is reduced slightly. The contact area should stay the same in theory but this is not the case in reality. As soon as the car moves the contact patch changes due to weight transfer etc. You also add tire pressure to the equation and it gets very complicated very fast because reducing the pressure effectively increases the contact patch aread because the tire flatens a little.
What I am trying to get at is that the tire is round meaning that if the contact patch is a rectangle pressure is nor distributed evenly across it, it is concentrated more towards the center line of this rectagle(line going widthwise across center of contact patch) because the tire is trying to stay round and this is where it exerts its most of its force. This means that the more area that you have close to this centerline(widthwise on the tire) the more effective the weight will be used to generate friction with the ground(smaller slip angle because you're closer to the theoretical contact line between the tire and the surface). This makes the longer, thinner contact patch of the wider tire more desirable for power transmision because althought in theory its contact area might be the same as the thinner tire's, it is more concentrated towards the place where most of the force is being excerted. The fact that the tire is wider also allows you to use less tire pressure for a given car weiht in turn widening the contact patch to match the width with a thinner tire therefore increasing total contact patch area.
I am not saying in any way that wider in rear is always better, as a matter of fact a factory rx8 would probably not benefit from this, it would probably cause it to understeer and loose speed due to weight too. I am just stating the reason that wider allows you more transfer of power in a straightline even if in theory the contact patch stays the same. I know this for a fact because I had to do a 1 year study on this matter as a final graduation project to my engineering degree and these were my findings after doing a lot of research and speaking to some of the senior design engineers at brigestone and goodyear.
I hope you are not offended in any way with this comment, I just wanted to post my findings, not discredit your statement.