MadDog

Wow, cortc. Nice wheels...I didnt' think that any aftermarket wheels would support the TPMS. Did you have to specify a specific option to get the TPMS on there?


Maddog

10000RPM

Best wheel/tire combo I have seen on a RX-8 yet!!!:D Exactly what kind of tires are those??? and one more thing, were did you purchase the rims.

cortc

MadDog: Thanks, yes many wheels do you just have to do your research or just try it out... You don't have to specify anything it has to do with the valve stem mounting hole, where it is located and at what angle it sits... Many one piece wheels work as do some multi-piece wheels; I got a TPMS sensor from our dealership and then tried it on the RIMS I was thinking about including the HREs... If you find something online, most vendors will let you ship them the sensor and they will test fit for you...

10000RPM: The tires are Hankook Ventus K104 235/35-19 & 265/30-19 f/r, I bought the RIMS and tires from local Axis and Hankook distributors through our dealership here in Miami at wholesale prices...

MadDog

So how much do those axis rims weigh?

cortc

MadDog: They are a little lighter than stock, will get exact weights and post...

Here is a link to Vivids write up on the StopTech brakes...

http://vividracing.securesites.net/i...=Project%20RX8

XcelR8

cortc...Very nice look on the 8, probably the best wheel combo I have seen yet.

cortc

Thanks...

pkwa

what do you do about the tire pressure sensors? and does the ecu like the slightly different diameter?

cortc

The difference in revolutions per mile is like 8-10, I don't have the chart with me but I looked it up... The ECU has no problem with the difference and the tolerance of the TPMS allows for a front to rear differential of about 6-8 psi...

The TPMS works perfectly, no problems what so ever; even tested it. Dropped the pressure and they went off at about 26-28 psi...

SDFLY

Looks sweet!

wayneside

nice!

jkamen

i will be stealing that fitment info when I get my wheels/tires. great work on the pictures and of course your 8.

WTF no turbo

Last time i looked rear hiro 19 9.5 weighed 27 pounds.Ship weight was like 30 pounds.Not knocking them they look great but i think your off on the weight.

Landon_Starr

Those wheels are WAAAAAYYYYY too beautiful to be wrapped with cheap Hankook rubber.

Bad-*** wheels!


--Landon

cortc

Those Hankook tires were rated as good as the S03s... I had S03s on my 996 and let me tell you; they are as good... If you prefer to pay more for the same quality than go for the S03s...

SHOWOFF

Those wheels are absolutely stunning on that car, good call!

flip

gotta love those wheels... me likes

SDFLY

Very nice choice and....take your own advice and let the more expensive HREs go by the wayside....

Kevin

casual

Sorry cortc, i stole your rim set for my eight over here on the left coast. They just look to sweet for such a good price. They look good on a titanium too.

just a question about the tpms sensors

on the stock rims the sensors rest against the inside curve of the rim i noticed on the hiros there is about a 1/8" space between the sensor and the inside curve of the rim is this something to be concerned about??
Also the tires are rated for 50 psi I read about your adjusting the pressures for understeer but 32 and 36 psi? is that too low for such low profiles? arent there any potholes in fla.?
might be a dumb question but this is my first sports car and I've never had low profile tires before.

also are those the only center caps avail from Axis? I havent got mine yet I guess the they are on back order right now. I still put the rims on cuz I just couldnt wait.

Thanks again

cortc

casual: These are the only center caps, but they are billet and very nice... Congrats, these are very nice wheels... The pressure is OK at 32-36 or you could go up to 34-38, 36-40 or even 38-42 if you like; that works too... But 32-36 is fine for this car and these tires... What size tire and offsets did you get? And post some pics, would love too see them on a titanium...

Oh yeah, the TPMS is fine how they sit on the hiro's... At high speed the force on them is to the outside; so even on the stock wheels they really have no support from the wheel structure anyway... I have had my car over 148 with no problems...

RotorManiac

I was wondering about the same thing. but how does the difference in pressure help with the staggered set up? heard ppl saying a rwd car should have less psi in rear wheels... could this be right?

cortc

No, they usually take more unless you are drag racing...

Sputnik

The two basic things that change when you adjust tire pressure is contact patch size, and the effective spring rate. There are other factors, and so there are limits to how much you can adjust tire pressure before other problems occur. And, you have less "range" on a lower profile tire.

For contact patch size, when you put more pressure in the tire, you decrease the contact patch size, and when you let pressure out, you increase the contact patch size.

For spring rate, the more tire pressure you have in a tire, the "stiffer" it is, giving you a higher overall spring rate to that corner.

I agree with Cortc in that what you heard about tire pressures in a rwd car only pertains to drag racing. In drag racing, you want as much grip on the driven wheels, in this case, the rear wheels. RWD cars have an advantage in that when you accelerate, weight shifts to the rear, so more weight is on the rear than the front. What you want to do is increase the tire pressure in front, which will decrease the contact patch (decreasing rolling resistance, think about how wide a front wheel is on a dragster), and stiffen the front suspension slightly. You then decrease the rear tires to increase the contact patch (more grip), and soften the rear suspension slightly. The stiffer front and softer rear suspension will cause more weight to transfer to the rear wheels for even more grip.

For a fwd car, you want to do the opposite for a drag racing setup. You want more pressure in the rear for less rolling resistance, and stiffer rear, and you want less in the front for a bigger contact patch and softer. The softer front and stiffer rear will cause less weight to transfer to the rear, and off of the driving tires.

You can also adjust tires to affect changes in handling too. If you have a 50/50 weight balanced car, and put wider rear tires on, there will be more grip in the rear. To try and balance things out again, you would decrease pressure in the front, and increase it in the rear. This will increase the tire contact patch in the front, and decrease it in the rear, getting them closer again. The softer overall spring rate in the front will mean that the front of the car will roll a little more in the turns, putting more downforce on the front tire, further increasing it's grip. At the same time, the stiffer overal spring rate in the rear will mean that the rear of the car won't roll as much, further decreasing it's grip.

The thing you have to consider is, will you have enough adjustment range in air pressure to balance things out again? Remember, if you do this on 19s or 20s, your adjustment range is much smaller than on 17s or 18s.

The other thing to consider is that when you do those tire pressure adjustments to balance out a car with staggered wheels, you will notice that you are doing the exact opposite of what you want to do to increase grip for drag launching. If you were able to adjust pressures enough to balance out handling once again, you've dialed out all of the advantages of a wider rear tire in acceleration.

As far as whether pressure adjustments are effective really depends on the car, and how you use it, but that's another post. What works for some people won't work for others. Just remember that when you are talking about tuning, whether it be engine or suspension mods, you are always making trade-offs. What you have to figure out is it an advantage for your situation, or does it come out to be no gain (or even a disadvantage) for your situation.

---jps

cortc

Sputnik: Well said, just one thing; if you go wider (Not to much...) f & r and then compensate with tuning and pressure you can increase lateral load and in affect cornering speed... The trade-off as Sputnik was discussing is you loose a little in acceleration... This is when you make power changes to increase hp and get it back, and then you want to improve braking to balance everything out (That is my current focus)... I always set up my cars for road racing, I do not care about absolute 1/4 mile and 0-60 times as they really have little importance in road racing (And the RX8 is really not setup for it)...

I plan on buying another set of rims, just for track days as my current setup is not really ideal for track use. It is a slight compromise in performance for style and strength… Will probably go with magnesium 8x18/8.5x18” and probably not staggered w/ pure DOT racing tires… And keep it 225/235 front or 225/235/245 rear combinations with real sticky tires and just play around with pressures… She is not a heavy car so this should work well… Once the hp goes up to where I want it (Target is 280-320rwhp…) I will probably be bored, so then it will be time to play around with Mazdaspeeds adjustable suspension setup…

This is a hobby for me and a lot of fun so nothing is written in stone…

coldnoodle

[QUOTE=cortc]MadDog: Thanks, yes many wheels do you just have to do your research or just try it out... You don't have to specify anything it has to do with the valve stem mounting hole, where it is located and at what angle it sits...
QUOTE]

So as long as the valve stem of the TPMS fits in the hole, it's should work, right?