Audii-Dudii

In preparation for competing in A-Street starting January 1st, 2014, as well as taking advantage of the new +/- 1" wheel diameter allowance, I've bought two used sets of 18x8.5/18x10 O.Z. Alleggerita wheels over the past six months.

Both sets use 18x8.5 ET53 front wheels, but one pair of 18x10 rear wheels is ET40 (Cayman/Boxster fitment) and the other pair is ET65 (911 NB fitment), so that I can tweak the final offset using spacers, because I like the flexibility of being able to run a narrower track on slower and/or tighter courses or on courses with a lot of slaloms.

Although the Alleggeritas are reasonably priced and reasonably light, I'm not particularly wild about their styling, although they're not so ugly that I can't live with them if I absolutely must:



That said, they're also a few pounds heavier than I would prefer, which will be a bit tougher for me to live with, as I tend to be OCD about weight, especially unsprung weight. (FWIW, with AD08 tires, my same-width 19" Champion RG5s are a whopping 17 lbs lighter for the complete set of four than my 18" Alleggerita/ZII combo ... and IMO, they're much better looking, too!)



The obvious solution is for me to buy a set of 18" RG5s, but I've had no luck finding a used set and unfortunately, a new set is way beyond my budget limit ... for now, anyway.

So I've started pondering less costly alternatives (assuming, of course, that I ultimately do decide to switch to 18" wheels, as my initial testing has shown the 19" wheel/tire combo to be consistently a few tenths of second quicker) and I am curious as to which wheels other Cayman/Boxster owners will be using.

Comments, thoughts and/or suggestions?

Audii-Dudii

Hmm ... TWS Motorsport's T66-F forged wheel looks quite interesting. Made by the same Japanese manufacturer that makes Champion's wheels, the 18x8.5 ET48 wheel weighs 7.32 kg (16.1 lbs) and the 18x10 ET60 wheel weighs 7.76 kg (17.1 lbs): http://www.tws-forged.com/tws_t66-f.html. This is approx. 10 lbs per set lighter than the O.Z. Alleggerita and the offsets are a bit more optimal to boot. (For a bit more money, custom offsets can be specified, but it appears there is a minimum order of four sets ... I'll look into this.)

At today's exchange rate, the 18x8.5 wheel is $680 per and the 18x10 rear wheels are $710 per, which is roughly $1k more than a set of Alleggeritas ... as I said, hmm. I wonder if there's any potential for a group buy here?

Audii-Dudii

So far, the Forgestar F14 wheels are proving to be the least expensive option, at $1,359.95 for a set of four: http://www.modbargains.com/Forgestar...he-18-Inch.htm.

The claimed weights are both ~.8 lb heavier than the O.Z. Alleggerita (18.5 lbs for an 18x8.5 ET48 front wheel) and about the same amount lighter (19.4 lbs for an 18x10 ET42 rear wheel), but custom offsets can be specified for no extra charge, which is a big plus, IIMO. I like their styling, too.

(Per the internet, early wheels had some QC issues, but a friend who has one of the early sets on his BMW has had no problems with his, so YMMV. In any event, the manufacturer claims those issues have since been addressed...)

Mport68

Don't the current SCCA stock class rules dictate that offset be no more than +/- 0.25 inch from OEM specs? I believe this rule carried over to the new street class. Not sure what your stock offset is, but the difference between the two OZ rear wheels you bought is 25mm or almost an inch.

Audii-Dudii

The wheel offset rule was revised for 2013. The effect of the change was to clarify that the offset of the wheel itself doesn't matter, only the net offset of a wheel/spacer combo. So long as that falls within +/- .25" of the OEM offset, then it's legal per the Stock and Street class rules.

As I understand it, this change was made to accommodate cars that come from the factory with spacers (or have them as an available option, as many Porsches do) so their owners have the option to run one spacer that combines the width of the factory spacer plus any amount of the SCCAs +/- .25" offset allowance instead two separate spacers, no spacers at all by choosing wheels with an appropriate offset, or some combination of the two (which is what I chose.)

In the case of my Cayman S, because the OEM offset for the 19x10 wheel is 42mm, this means that any net offset between 35.66mm and 48.34mm is legal per the +/- .25" allowance. If one wishes to also use the 5 mm spacers that were an available factory option for this car (option code XRP), then the allowable offset range becomes 30.66mm to 43.34mm.

Of course, since the factory spacers were used on all four wheels, not just the rear wheels, the allowable offset range for the front wheels also changes (in this case, from 48.66mm to 61.34mm without the factory 5mm spacer to 43.66mm to 56.34mm with the spacer.)

Thus, my 18x10 ET65 rear wheels, combined with a 22mm spacer, have a net offset of 43mm and therefore fall well within the allowable range...

sjfehr

...unless there was a 0.35mm machining/rounding error, in which case you're out of spec

Audii-Dudii

True, which is precisely why I verified their compliance by measuring everything myself ... three times, in fact, just to be safe! <crosses fingers>

Audii-Dudii

Well, as it happens, I have found (and purchased!) a used set of hard-to-find Cayman/Boxster fitment 18" Champion RG5 wheels (18x8.5 ET50 / 18x10 ET38), so the wheel search I was documenting above has now come to an end. (I paid a bit more than I would have liked, but as this was only the second set I've seen for sale in over a year of diligently crawling around the 'net looking for them, I sucked it up and paid the seller his price...)

As a heads-up, in case anyone reading this might be interested in one or both of them, I will be posting both sets of my O.Z. Alleggerita wheels for sale shortly...

sjfehr

Wow. Congrats on your find- I was figuring you'd eventually just have to custom order a set.

Audii-Dudii

Hah! I'm afraid I'm too cheap -- er, frugal -- to ever do something like that.

XPC5

Where do you think your 19" combo is making the time improvement vs. your 18's? Aren't the 19" tires even taller than the 18's? I remember over 10yrs ago when the first ultra low profile 18in hoosiers came out (285/30) what a radical improvement in steering and cornering feel and precision that was, are 19's going to be the same? (cost, and sizing issues put aside).

Audii-Dudii

I can't yet offer any hard evidence to support my mental impressions -- a datalogging setup is in the 2014 budget, not the 2013 budget -- but in general, I'm finding the 19" tires do corner entries better as well as transitions (i.e., slaloms), both of which are things one would intuitively expect a lower-profile tire to do better. (In fact, one of the problems with my driving that I'm struggling with is the fact that on 19" tires, the Cayman is turning quicker than I expect, so I'm having difficulty properly leading the car. Back in the day, before I took two decades off from autocrossing, I was something of a slalom master, whereas today, I find them to be my most glaring weakness.) And with the Cayman not being the most powerful car around nor a low-end, torque-monster, I find it exits corners on 19" 30-series rear tires no worse than it does on 18" 35-series rear tires, so it doesn't appear there's any significant penalty with respect to longitudinal acceleration, either.

Yes and No: The front tires are .2" taller (19" - 25.2"/18" - 25.0"), but the rear tires are the same height at 25.6" for both the 18" and 19" setups. I am finding the reduced stagger with the 19" tires as they wear ultimately causes ABS/braking issues. (Everything is fine when the tires are new and the stagger is .4", but the rear tires wear more quickly than the fronts and once the stagger falls to .2" or less, the car starts getting squirrelly under braking and/or does the "ice mode" dance. I know that many people happily run square setups without any issues, but this is not the case with my car or perhaps more appropriately, with my driving style and my car. Try as I might to drive smoothly, I tend to be more of the pitch-and-catch type, so YMMV.)

Unfortunately for you, the limited selection of 19" R-compound tires makes the 19" v. 18" debate a moot issue. But the difference in steering response and cornering feel that you've noted is very apparent between 30-series and 35-series tires and so far, as things stand today, I much prefer the lower-profile setup. That said, I'm approaching the 18" tires with an open-mind -- otherwise, why would I be dropping serious coin on another set of wheels so I can make a proper apples-to-apples comparison? -- and at the end of the day, I'll run whichever setup (or combination of the two setups!) is quicker.

XPC5

Thanks for the insight, I am looking at a gen2 car to replace the current that has oem xrr wheels, so may get a chance to try it next season. Good luck with the coming season.