Eric13

I ran a few events early last season on worn out RS3's with a set of 17x9s until I got busy with work and sold them since I wasn't using them. I loved running something other then stock wheels/tires. I would like the price to stay around $1000-$1300. I was looking at Z2s and Rivals mostly which are already $700 so that narrows my budget down. Any ideas? I'm completely stock, not one thing done to the car besides an alignment.

ABQautoxer

STX legal TRMotorsport C3 wheels in 17x9 (www.tirerack.com and select Mazda, 2006, MX5 SCCA STR Class). Any of those tires or even Kumho XS, Nitto NT05, or Falken RT-615K would work for the track and be decent enough for autox. There are cheap XXR and MB Motoring type wheels if you don't mind running an off brand. I've used different XXRs for PCA events just fine.

MikeTyson8MyKids

iTrader: (1)

Tires need to be 200tw or greater. Dunlop z2, bfg rivals, or re-11a.

ABQautoxer

Not until 2015.

MikeTyson8MyKids

iTrader: (1)

Correct. But, minus the R1R is special circumstances, there really aren't any good ones not rated 200.

Eric13

I'm trying to spend as little as possible on the wheels since I'm upgrading to an Evo X around August/September, the tires will be where I'm investing money so I can get as much seat time as possible. I'm thinking RS-3 or Z2s. I do not mind running an off brand at all. Will weight be a big problem? Also will going to a 17x8 wheel hurt me? The below is a few options I found.

3 - 17x9 Rota Grids (a 4th will need to be purchased) - $300 - weight/20lbs

4 - 17x8 Evo 8 wheels - $350 - weight/21lbs

4 - 17x9 MB Weapons (new) - $500 - weight/21lbs

4 - 17x9 TRM C3 (new from Tire Rack plus shipping) - $700 - weight/19.6lbs

ABQautoxer

No. Despite conventional wisdom you'll see in autox circles, test have been done that proved taking several lbs off each wheel did nothing for actual times. However, the idea that is good is getting total weight off the car and as much unsprung weight as possible such as wheels. With that said, 2lbs on a budget build is nothing to me. At this point you are just concerned about seat time.

As for width, RS3s do not like being pinched. Also they are hard to find as they are switching to the replacement tire due out sometime this year so they will get harder to find as time goes on. Z2s pinch rather well by comparison. They both have very different preferred operating temps.

MikeTyson8MyKids

iTrader: (1)

C3's with Z2 would be my pick with everything you've mentioned. Rs3 aren't really available anymore...probably something new from Hankook soon.

Eric13

I'm really leaning towards the Evo 8s since they are cheap, but them being 17x8 and not 9s is my only concern. I'm not sure what size of tire I should put on them.

Well, I did have a set of RS-3s ready to order two days ago, but it looks like they are now on back order. :/

As far as getting the C3/Z2s I would love the most, but at almost $1600 it is just way too much for me to spend with just having them for 5-6 months. I don't mind spending the $750 from Tire Rack on a new set of Z2s, but really just need to find a cheap set of wheels for now. Once I have the Evo X in my possession, the wheels will get my full attention first.

ABQautoxer

But those C3s will likely sell for a better price (less loss) than the others. MX5s and RX8s use that exact size for STR/STX.

MikeTyson8MyKids

iTrader: (1)

Exactly.

Larissa8

I'm pretty much in the same dilemma. I'm interested in what you guys think between the rivals and the dz2 for autocross in our cars. I know mikekuhn likes the rs3s over both but it's hard to find them nowadays. Based on what i've read so far, please correct me if i'm wrong, the rivals have more overall grip but the dz2 has quicker response and better overall feel.

marka

Howdy,

First, if you want to be in CS you need to have 8" wide wheels. I would make that choice first, since it will dictate which wheels you're going to be most attracted to.

Remember that you can just not buy wheels at all. There are good options for tires for stock 18x8 wheels and z2's in particular are a perfectly fine street tire. Rivals aren't much worse... I drove my car six hours to Peru last year with the Rivals on through rain storms and didn't have any "I'm going to die" moments at all. These are actual street tires.

Second, z2's vs. Rivals vs. RS3's vs. Toyos... Unless you're going to be at nationals and are concerned with winning, I think you can just throw a dart at this and buy whatever it lands on. All of those tires were represented at nationals and did reasonably well. I've tested z2's and Rivals back to back both locally and at nationals and found the difference to be quite minor and as much down to what I preferred in terms of feel vs. outright time. For instance, it is absolutely true that the z2's light off faster than the Rivals which are in turn faster than the RS3's in terms of "heat required", but again this is a small difference on the clock. I wouldn't worry about it very much for a budget build.

Mark

TeamRX8

iTrader: (25)

There are a few sets still around of the 140TW Hankook RS3 tires despite the 200 TW rating being out now. ...

Eric13

Thanks for the help all, I ended up going with the 17x8 Evo 8 Enkeis, they came out great on my car. The +38 offset bumped me out of CS, but I'm happy with STX in my local region we have about 10 people now. I settled on 245/40/17 Z2s, so far I love them, I've put about 50 miles on them so far just running them around town. Yesterday our event was canceled due to weather so I didn't get to test them, but I'll be running this Sunday for sure!

marka

Howdy,

If anyone is looking for CS legal tires with or without wheels, I just posted a set for sale.

https://www.rx8club.com/rx-8-parts-s...6/#post4604726

Mark

tpdrx8

If you just need a second set of wheels that meet stock requirements:

https://www.rx8club.com/rx-8-parts-s...ta-p1s-253592/

If you want lighter ones that are in better shape:

https://www.rx8club.com/rx-8-parts-s...s-ssrs-253591/

arvigovi

Trying to squeeze a question in here because I am not approved yet to start a new thread. I have been autocrossing the RX8 for about 2 seasons now in CS. Currently running 245/40/18 Rival's on stock rims. While I am quite happy with the grip and overall performance of the setup - very unhappy with the steering feel - quite often I am feeding in too much steering input around sharp turns - and I don't seem to know what the front wheel is doing - it feels like driving it with a remote control. Would love to have inputs on how I can improve steering feel within the limits of CS - should I try different tires, aspect ratio, alignment, anti-roll bars? Any input will be appreciated. My current alignment: Front Camber - 1.3; Rear camber - 2.5; Front Toe - 1/8'' Toe Out; Rear Toe - 1/16'' Toe In; Suspension (Koni Single adjustable) - Rear suspensions: 50%, Front - 50%

marka

Howdy,

Your front and rear camber are pretty crazy. Are you sure those numbers are right?

I run max front camber / min front caster (-1.7 left, -2.0 right, caster around 5 deg), with rear camber about half a degree less. A little front toe out (-.27 deg, which IIRC is around an 1/8"?) and zero rear toe. Front bar is slightly stiffer than stock. I have revalved Koni DA shocks, so my shock settings aren't going to directly compare, but my guess is that you'd also like more rear rebound.

All that said... One of the main things I didn't like about the Rival when I ran it was front end feel in our car. I switched to the Dunlop z2 and liked it much more. I could feel what that tire was doing. Since then I've switched to the Hankook to chase contingency and the front end may be a touch worse, but its not horrible.

Note that this isn't a particularly scientific comparison, as I've not back to backed the Rivals vs. the other tires directly and I've made other tweaks to the car along the way (bump stops & rear rebound particularly).

My guess is that most of the push you're experiencing is the alignment & rear rebound setting. Fix that and give it another go.

Mark

arvigovi

Thanks a ton for your input Mark. Those camber numbers are correct - they are a bit weird (but the idea was to maximize front/rear camber) - the most I could get out of my front was -1.3. Rear went up to -2.5. It was more an exercise of maximizing change to observe the effect - have to run at -3PSI in the rear to be close to neutral. Otherwise the rear steps out all over the place. I really dislike the current setting.

* Were you able to achieve -1.7 and -2 front camber with the stock setup? Does that mean your rear is at -1.5 roughly?

* Another thought I had was if I should try slightly narrower lower profile tires - like the 235/40 Dunlop ZII - is there a grip Vs feel trade-off on the 8'' rims?

* One thing I did notice with the Rival's - they have extremely stiff side-walls. They rolled to the same point across a wide range of tire pressures. Is that the reason they feel numb with our cars?

* I have a Hotchkis front anti-roll bar sitting around. Is there a recommended setting to start with - in combination with front rebound setting? Which are the only 2 variables I can adjust outside of the alignment.

Sorry for the tons of questions. Really appreciate any inputs or comments - my goal is to have a competitive CS setup with close to neutral handling.

marka

Howdy,

Yes to both questions. I'm on converted / degassed DA Konis which I think drops the static ride height a bit compared to the old regular Konis I had before, but even with those I was at around -1.5 on both sides up front. It might be worth some investigation here on your part, to make sure the front subframe / bolts / eccentrics / whatever are all in good shape.

I ran the 255/35-18 z2's on 18x8's and liked them. The z2's have a very, very stiff sidewall. My guess is that they do better with 'over-tiring' than some other 200+ tires.

I dunno. For me, I think it was more about how the grip changes with slip angle/input. The Rivals reportedly have a very flat plateau of grip and I think I instinctively don't feel that as well as a tire with a more pronounced grip peak. My guess is that translates to a numb feeling.

In your case however, my guess is that the excessive rear camber & lack of rear damping is causing your car to be quite pushy, which is translating into that numb feel you're talking about.

Which bar? My front bar is either a Hotchkiss or Progress front bar for an MX5, which is slightly stiffer than the stock RX8 front bar. The bars they make for the RX-8 are all, IMHO, probably a little too stiff.

No worries, I hope it helps. There's another thread here dedicated to this kinda stuff that might be worth reading / moving discussion to: https://www.rx8club.com/rx-8-racing-...ecipes-235463/

Mark

arvigovi

Thanks a lot again Mark. I will try the alignment changes and report the results. I did go over the CS/BS recipes thread many times - should have posted there right at the start - my bad. I will continue this conversation in that thread once I have some results from the changes.

mbirt

Hey guys! I've got a 17" tire sizing dilemma for CS competition. I have a 2009 GT (SII with shorter final drive), so I'm not sure if I should go with the conventional wisdom of going down in tire diameter for autocross. Last night I picked up a set of 17x8 WRX STi wheels (BBS forged, will run a thin spacer to deal with the +53 offset) for $200, offset by the ~$200 cost reduction from 18" to 17" tires.

At 9000 rpm in SII 2nd with a *.965 fudge factor, the following speeds are attainable:
235/45-17 245/45-17 255/40-17 225/45-18
60.61 61.46 59.91 62.16

245/45-17 seems to be the size to go with considering the shorter gearing of the SII. The issue is that the ZII is the only (200 TW) tire available in this size and the 255/40-17 R-S3 v2 is $21 cheaper per tire. The 235/45-17 R-S3 v2 is cheaper yet at $139 while the ZII in this size is $151.

Are there any tire-specific sizing nuances relative to the wheel size I haven't heard that could make this selection easier? Is 255 too much tire for a CS RX-8? I'll be daily driving on the 600 TW Kumho's that came on my stock wheels.

marka

Howdy,

The jury is still out on how well the tires work from over-tiring. Most folks agree that there's no benefit to overtiring to the extent that was done on the DOT-R tires, but there's not enough data to suggest that a Hankook RS3 255/40-17 is actually slower than a 245/40-17, for instance. Note that this is also likely to be tire model specific (for instance, I would expect a very stiff sidewall tire like the Dunlop Z2 to work a little better in an overtiring situation vs. a fairly soft sidewall tire like the new RS3.)

Your top speeds there are all within a couple miles per hour. I'm not going to say that doesn't matter, but I will say that you need to be at the very pointy end of the field before it does and even then... Likely there will be other offsetting factors.

If I were you, I wouldn't be selecting between these tires based on gearing, or at least not with that as the primary factor. If it were me, I'd probably run the 235/45-17 RS3 or possibly even the 245/40-17 if I ran mostly at places where top speeds weren't that high.

I'm running the 245/40-17 on a 2005 and the gearing is still a decent bit too tall on average. Very occasionally its an advantage on a course that has a higher speed section (Toledo this past weekend counts), but even in those situations there are probably a lot more places on course where you want more power coming off a corner more than you care about having the ability for a slightly higher top speed.

Mark

mbirt

Thanks for the advice Mark! I just pulled the trigger on a set of 235/45-17 RS3's. I'm excited to leave the local novice pax and start giving the twins and Z's some trouble in CS.