Teach me .... Wheel selection for performance

So I am looking into getting some new shoes for the FC. Being cheap I've always stuck with stock wheels for all my previous cars.

Can someone explain to me what the advantages/disadvantages is of getting aftermarket wheels. And how I should go about figuring out the size of the wheel like diameter, width, offset.

And for those who have experience with rx7s let know what you have and how you like it. I've already checked rx7club but the focus there seems to be superficial rather than performance.

The car is a weekend/autox. I do care about how it looks but I also want to make sure my money also helps in the performance department.

From a physics stand point go lighter is your #1 priority. Every pound you get rid of rotationally is worth 3 pounds in the car. So you get 12 pounds off your wheels (3 each) which shouldn't be too hard, is the equivalent acceleration wise to removing 36 lbs from the car. Best place to lose weight is rotational mass. But you will lose some of the smoothness in the throttle by losing fly wheel effect.

I would check and see what the competitive tire and size set up is for your class and get the lightest wheel you can stand the style of that will work there.

Don't get anything larger than required to fit over your brake calipers. You might find some light 19" deals, but the rotational inertia means something, too.

Also you get what you pay for is a half a second worth an added $1500 in an amateur field? but on the cheap these guys are ugly but at 15 pounds you cant beat the price and you can always paint them to suit you. http://www.tirerack.com/wheels/WheelCloseUpServlet?target=runWheelSearch&initialPartNumber=TS105O&wheelMake=Kosei&wheelModel=K1+TS&wheelFinish=Orange+Painted&showRear=no&autoMake=Mazda&autoModel=RX-7&autoYear=1986&autoModClar=&filterSize=All&filterFinish=All&filterSpecial=false&filterBrand=All&filterNew=All&sort=Brand and you can fit a 225/40/17 with out having to do much more than roll the inside of the fenders. depending on how aggressive you suspension setup is

You can fit a 235/40/17 F 255/40/17 R no problem.

Or some 225/50/16s all around would be a cheap upgrade. Stock FC fenders with just a roll can fit lots of rubber.

What are you trying to do? street car? autox? trackdays?

~Alex

I found changing from curb friendly OE 15" wheels to Rota Slipstreams, plus a lighter tire (total about 5 lbs a corner) made the shocks work so well I forgot about trying to find something better. Light is good. I'm a believer now.

Invest $40 in a NASA membership and you get a year's subscription to GRM and a huge discount on Konig wheels.

As mentioned many times before, lighter is the main goal, but wider also helps Someone familiar with your chassis can help you determine what widths and offsets work.

The smallest diameter wheels that will fit over your brakes will give you the lightest wheel with the smallest rotational inertia, but another factor comes into play - tire availability (and in some cases wheel availability too). Case in point - my first gen MR2 can fit 14" and some 13" wheels over the brakes, but there isn't a selection of ST-autocross-competitive street tires until you go with 15" sizes. They make R-comps in just about every size, but depending on your class restrictions or budget they may not be an option.

Here's a nerd moment on rotational inertia, calculated by the moment of inertia. I'm going to simplify it by assuming a wheel is essentially a flat "ribbon" hoop around the axis, ignoring the center spokes since a wheel's rim makes up the majority of the mass. The energy required to start that wheel moving (moment of inertia) is calculated by it's mass multiplied by it's radius squared.

I = M(R^2) (I think I just made an MR2 joke there)

So in effect, the radius by itself will exponentially raise the MOI, regardless of the mass. Translate - small rims are fast.

Matt B wrote: The smallest diameter wheels that will fit over your brakes will give you the lightest wheel with the smallest rotational inertia, but another factor comes into play - tire availability (and in some cases wheel availability too).

Yep. The lack of tire and wheel options were a bit of a rude awakening when I bought my E30.

FlightService wrote: Best place to loose weight is rotational mass. But you will loose some of the smoothness in the throttle by loosing fly wheel effect.

Lose

Am I the only person that noticed everyone is saying just what I said only re-wording it?

Light weight

Hot tire and wheel size set up (which will dictate wheel size - which will dictate a small diameter.)

Why is everyone repeating me? I say something and then someone else is saying it with different wording.

Less mass is good

Tire size, availability, and competitiveness, given it's an older car and already sorted. (which will intern give you a wheel size that it competitive.)

Let me just add, Less mass is good.

Oh my. I need those orange Koseis. Pretty sure they fit on my car, too. How awful will orange look on a red car?

Wait... that link is saying they're 4x114. Weren't FCs 5x114?

The car is going to be for AutoX and for the weekend. The bolt pattern is 5 x 114. I am thinking about just getting some 16's seeing that the stock wheel is 16x7 +40.

I'm seeing a lot of wider wheels and staggered setups on RX7club. I was looking at the Rota Slips and they seem to have them in the exact same size. Should I go for it? do I need to go wider that stock?

Thanks for the responses guys keep them coming

FlightService wrote: Am I the only person that noticed everyone is saying just what I said only re-wording it?

Yes.

Nis14 wrote: The car is going to be for AutoX and for the weekend. The bolt pattern is 5 x 114. I am thinking about just getting some 16's seeing that the stock wheel is 16x7 +40. I'm seeing a lot of wider wheels and staggered setups on RX7club. I was looking at the Rota Slips and they seem to have them in the exact same size. Should I go for it? do I need to go wider that stock? Thanks for the responses guys keep them coming

What class (if any) do you plan on running in? Stock requires the same width as OE. Street and prepared classes are more open. The general rule is go as wide as possible without having the cut anything.

Staggered set-ups on a RWD car tend to be more from straight-line running and to induce understeer. I would not run a staggered set-up for auto-x unless you are looking for a specific handling trait.

Well, I’m running an upgraded turbo and coilovers. So I think I have to run prepared class (I think). But my main concern is like the other guys have warned tire availability. If I go wider like 16x8 or 16x9 (do they even make these?) will there how would that effect tire availabilities and cost? Sorry once again come newbie when it comes to this proponent

So staggered is out of the question…. Thanks.

I run late 90's Mustang GT wheels on my FC. They are the proper backspacing and bolt pattern. I would recommend getting the ET style lug nuts (the ones that go through the wheel stud holes on teh wheel). These wheels are NOT hub centric.

They are cheap. I weighed mine at 17.7 lbs each for a 17 inch wheel is not bad!

wvumtnbkr wrote: I run late 90's Mustang GT wheels on my FC. They are the proper backspacing and bolt pattern.

If you're looking to go that route, what you're looking for is '94-'04 Mustang wheels. '79-'93 are all 4-lug other than the SVO and '93 Cobra R, and '05 and newer run wheels with ~1" deeper backspacing.

wheel & tire guide

http://www.motoiq.com/magazine_articles/articletype/articleview/articleid/1424/pageid/1734/the-ultimate-guide-to-suspension-and-handling-part-1-wheels-and-tires.aspx

Nis14 wrote: Well, I’m running an upgraded turbo and coilovers. So I think I have to run prepared class (I think). But my main concern is like the other guys have warned tire availability. If I go wider like 16x8 or 16x9 (do they even make these?) will there how would that effect tire availabilities and cost? Sorry once again come newbie when it comes to this proponent So staggered is out of the question…. Thanks.

Depends on the tire size you want. 245/45-16 is pretty much gone, unless you're cool running Fuzions or Toyo RA1s, or slicks. There's really no in-between.

265/45-16 is available. So is 225/45-16.

I'm currently in the same boat with my 16x8s on the Celica, and i'm deciding if i want to pony up for the RA1s in 245/45-16s, or just go with 225/45-16 R1Rs.

I'm looking at the Rota Slips in 16x8 +40

What would be the optimum tire size for this wheel for autoX? I read the article posted above and it says that for autoX you can stretch the tires a bit. Once again, I've been using stock tire sizes all my life so this stuff is new to me.

Very excited to learn more.

Thanks guys.

FD RX7 wheels are 16x8 ET50 and weigh under 15 pounds. Oh, and I happen tohave a set for sale.

I'm almost certian that upgrading the turbo will put the car in Street Modified, so you're basically free as far as wheel/tire combos. Street Prepared allows upping the boost, but not swapping the turbo.

Nis14 wrote: I'm looking at the Rota Slips in 16x8 +40 What would be the optimum tire size for this wheel for autoX? I read the article posted above and it says that for autoX you can stretch the tires a bit. Once again, I've been using stock tire sizes all my life so this stuff is new to me. Very excited to learn more. Thanks guys.

Strictly speaking width, 225-245 is what you should be looking at.