Cloud9...68

I'm currently running 17 x 9" 996 Twists with a 55 mm offset at all four corners on my track-focused 1992 968. The car has 2-1/4" id coilovers all around, and I measure a 17 mm gap between the inside of the front wheels and the spring, which says I should be able to fit 17 x 10's with the same offset without the need for spacers. I want to stay with 17", because 18" tires in the same width and overall diameter cost about $250 more per set. I do at least a couple of sessions a week at the local track, so I go through tires fast, and this adds up for this father of two daughters in college. Plus, 17" wheels are generally lighter, and just seem to be more in the "sweet spot" for these cars than anything larger.

I have spent many hours searching, and outside the uber-expensive realm of custom wheels like Forgeline, Fikse, Braid, Joengbloed, etc., I haven't found anything. None of the 17" OEM Porsche wheels on this list

http://www.944racing.de/wheelweights.php

come in a 10" width. Does anybody here know of anyone who makes a wheel in that size, ideally (although this might REALLY be dreaming) for $500 or less? Thanks.

951and944S

CCW...?

You could pick up Fikses used for $1200, I bought 1of2 sets I have for $1070 shipped.

Configure the outer barrel to your liking if you find some 8s or 9s.

T

jeffro951

What tire size are you running? I want to run a square setup as well but I still need 2 9 inch cup2's to make the set just wondering what the best tire size to use...

Cloud9...68

Whoa... that is a loaded question about a controversial topic. Prepare for some highly varied opinions. Here's my opinion/experience. I used to belong to the conventional stuff-the-widest-tire-you-can-on-the-wheel school of thought. Then I read an article in Grassroots Motorsports, followed up by several that confirmed the first article's conclusions, that the best results, both in terms of lap times and subjective feel, are obtained by doing just the opposite - squeezing the narrowest tire that can fit on a particular wheel. In other words, the width of the wheel matters a lot more than the width of the tire - get the widest wheel you can fit, then put as narrow of a tire that can fit on it. Putting a wider tire on a given wheel just gets lost in sidewall flex.

So, after talking to another Rennlister I've grown to respect who shares this belief, I dropped from a 245/40-17 to a 225/45-17 on my 17 x 9" wheels. Now, I also went from a BF Goodrich Rival to the Rival S, so it isn't an apples-to-apples comparison, but my lap times took a substantial drop, and the car felt noticeably crisper and more responsive to steering input. So, I'm sold on this approach. Maybe the fact that I have solid or spherical bushings everywhere contributes to my car's sensitivity to tire flex. My plan is to go to 255/40-17 tires all around, and to fit them onto either 17 x 10, or maybe even 10.5" wide wheels. Pandora's box officially opened...

jeffro951

I am running manual steering so a 225/45-17 would be great up front, I was thinking of 245/40-17 all around or maybe even 255's. My car being turbo I still want as much rubber in the back as possible. Thanks for sharing your experience. I am not doing a lot of track days yet so I am looking for a balance of economy and performance.

rlets

I agree 17x10 with 275/40 square would be an ideal setup.

Right now I run the 255/40 on 17x9 CupII wheels that I pieced together from 2 sets of 911 cast offs. The set of four 7s I sold to a VW Vagagon guy.

You might could do the same by buying 2 sets of aftermaket 911 wheels and use the 4 rears.

Cloud9...68

What you're describing is exactly what I have now. But I'm getting crushed by a guy in a stinkin' NB Miata. His car, like mine, has essentially a full race suspension, with 15 x 9" wheels (225-15 tires - can't remember his aspect ratio). So he's running exactly the same width wheels and tires as I have, on a car that weighs over 600 pounds less. I can sorta keep up with him in the tight transitions, surprisingly, and have an advantage in the straights, but he absolutely destroys me in the fast sweeping, "no-skill", just-hang-on turns. He just has vastly more grip than I do, and reels me in as though I had my parking brake engaged. I have tons of room, both inboard, because of my 2.25 id coilovers, and outboard, because of our wonderfully flared fenders, to fit much wider wheels. Honestly, I think I could fit 11" wheels on this car. I want to stay with 17", because tires are so much cheaper, plus they're lighter, and I don't want to go any taller than the stock overall diameter of 25" because this will raise (numerically lower) my final drive ratio, costing me precious revs at corner exit. This narrows down my tire size to 255/40-17. A 275/40 would be way too tall. Bob Woodman Tires found a set of BBS E26 wheels with magnesium centers in 17 x 10.5", which should be a perfect width for a 255 section tire. I will most likely pull the trigger on these wheels.

951and944S

Square front to rear is always a plus. You get to move the tires anywhere you want them.

A fast......fast Miata with a fast driver is a good match for an NA 2.5 944.
I could hold off the top few faster ones at our local series and let them go if I wanted to or not (not directly racing them) in a 2600 lb 140 rwhp car on RA1s (140 @ 2350 for the SpecM).
Generally, they would qualy 1-2 seconds slower than the top 944s.

No way you should be getting "crushed" by a second gen Miata with 245bhp, even with the extra 5-600lbs.

Everything in road racing i based on power to weight.

You have him covered by almost 5 lbs per horsepower, 12.45#:1hp vs 16.80#:1hp.

What track is this, COTA...?

I would take the wheel/tire money, wait for a PCA HPDE joint sponsored by Lone Star and Hill Country and get a good "race instructor" to push you to find the time you are leaving on the table.

T

Cloud9...68

The track is Driveway Austin, and it has three configurations - a very tight, technical 0.7 mile course a C5 Z06 can barely hit 80 mph at the end of the one straight, an intermediate course that's a little over a mile, and the full course which is about 2.2 miles. I'm talking about the 0.7 mile L1 course. This guy regularly passes C5 Corvettes, GT3's, Caymans, M3's, and just about anything else not driven by a professional driver. It's just a super well-sorted car. I've driven it, and it feels like it has unlimited grip compared to mine. I've also ridden with the owner, who's a friend of mine. He's a good, aggressive driver, but he's no Ayrton Senna. On the intermediate course, we're pretty closely matched - I'm slightly faster, actually, and more consistent. On the long course, I would walk away from him. But on the short course, the fact that he has the same amount of rubber on the road with 600 pounds less weight is just too much to overcome - there just aren't enough sections where my superior power-to-weight ratio can make up for the fact that he has so much more grip. And as I said in my last post, he pulls away from me the most in the turns that most resemble a skid pad, where we just hold the wheel in a constant arc, and input as much throttle as the car will take without leaving the track, where driving skill is not a major factor.

We hadn't driven together on the L1 course in the past. I thought it would be a good idea, since I had a 7-month layoff, to do a few sessions on the L1 to get re-acclimated. We had always done the L2 course together, which was a lot of fun since we were so relatively evenly matched. It's been a shock to see him walking away from me on the L1, but that version of the track is tailor made for a car like his. And it has opened up my eyes to the fact that while my car is very well set up, the tires just aren't providing a level of grip that the suspension is capable of delivering.

951and944S

Ah, ok. Had a look at it. That's pretty tight, we have kart tracks bigger than that L1. The L3 full experience looks pretty cool though, never knew this place existed so I thought you meant COTA.

If you don't really run this configuration often, still,, why try to tailor your car just for this...?

You never did say (or I missed it) what tire are you using.

Do you have at least adjustable rear sway bar...?
Do you have a street (shop manual recommended) alignment...?

Do you left foot brake...?

T

Cloud9...68

First, to answer your questions about my car, I'm running Nitto NT01's, have an aggressive, full-track alignment , with -3.4 degrees of camber up front, and -2.5 degrees in back. Yes, I have an adjustable rear sway bar, set to the full soft setting, which helps keep the car very well planted coming out of turns. I also have basically one of everything Racers Edge sells - his full complement of solid/spherical bushings, camber plates, 2.25" id coilovers all around (torsion bars deleted), half cage, and too many other things to list. It's just gotten corner balanced, and aligned.

To answer your question about why I'm so obsessed with matching this pesky Miata on a track configuration where he has a clear advantage, that's a good question, with several answers (all up for debate, I'm sure). First, I view the L1 course as being analogous to a skid pad, and it has highlighted the fact that my car's cornering power has a lot of room for improvement. Fixing this will make the car faster on all tracks and configurations. Also, Driveway Austin has begun running time trials on the L1 course, and with my current set-up, my car just wouldn't be competitive. And finally, just on principle, I hate getting beaten by a car that costs a fraction of what I have into mine, which I understand is pretty silly, considering we're not actually racing. But he's been making rumblings of turbocharging his car, and with my current set-up, I would have to resort to cunning and treachery to keep up with him even on the longer configurations

rlets

Awesome! I love the competitive development. I too am in DE competition with friends that drive older 911s: 2 RSAs, 964t, and a widebody '73. All solid drivers and we're all within a couple of seconds around our local track.

Those 10.5 BBS wheels sound sweet! And I see what you're going for with tire sizes. (I read the same GM article.) You mention a 245/40 tire size but Nitto doesn't currently have it listed. An S2 trans with it's lower final drive would keep those revs up even with 25"+ dia tires...

Rich

Cloud9...68

Thanks - yes, it's fun to have some friendly competition, even if Mr. Miata spent less on the initial purchase of his car than I did on my shocks! Trying to go toe-to-toe with such a light car with so much rubber on a track that is actually ideally suited to a go cart has really forced me to focus on my driving technique, and has highlighted where my car has room for improvement.

I'm definitely excited about the 10.5" BBS's - a post I found on a BMW forum indicates they're actually significantly lighter than the 21 lb 17 x 9" Twists I'm running now, so it appears to be all upside. The continued exercise in weight reduction (I'm talking mainly about my wallet!) can't be ignored. I'm planning to go with 255/40-17 tires - Nitto NT01's are available in this size, as are a host of other really highly rated tires.

sm

You're piqued my interest! Can you post a picture of the 225 tires on the 9" rim? I have the same wheels, and never knew a 225 tire could fit on it. Are the 225 tires VERY stretched on that 9" wheel?

Oddjob

BBS E26 17" will be around 17-18 lbs. The older E50s were somewhat lighter, 15-16 lbs, and the new replacement aluminum E87s are heavier.

Watch the E26s for cracking over time. The cast magnesium doesn't last forever and the E26s are known to crack at the spokes and around the lug nuts.