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I'm in the middle of a couple of projects on my '87 S4 (timing belt, water pump, new clutch, new tires, etc). My desire is to put the below tires on the car:
My preference is 235 to 245 on the front, and 285 to 295 on the rear.
My rear fenders are rolled, and the car is currently set to the lower end of the stock ride height specs.
I currently have hollow spoke turbo twist rims. The rears are 18x11 ET45, the fronts are 18x8 ET50. While the tires that I want would fit on the rims, and the rears should fit due to the rolled fenders, the fronts definitely will not fit. Even with the current 225's on the front rims, I get a little fender rub under very hard cornering.
I've done the math on the various tire options to determine overall diameter:
I believe that any of the above would work, but the real problem is finding wheels that will fit as good as possible. So far, the only options that I've come up with are:
Are there other options that people are aware of? 18" or 19" should be ok. A decent offset and the correct bolt pattern are the two things that I am having the hardest to find together.
Before I make a decision based on what I've found so far, I would welcome any additional suggestions on wheels that will fit the tires that I've selected.
Thanks. I do have LSD, and I have experienced understeer with the current setup when autocrossing. So, I know that the narrower rear tires will help with that, but I am making this decisions with personal aesthetics in mind as well Either way, I can't even put 235's on my current ET50 wheels without exacerbating the fender rub situation, so I need something else. Any suggestions on wheels?
Thanks, that is really good to know that those size tires fit. I think that the rears are 9" wide, right? The tires that I picked out say that a minimum of a 9.5" wide rim is needed for their 285 width tires. What tires are you running on yours? I'd like to look up the specs on them and see if they say the same thing. If so, maybe the ADVANs will fit on the rim as well.
The first question you need to be clear about is "what exactly do you want to achieve"? Many folks talk about wheels "fitting" when in reality they should be talking about wheels "working".
Many will tell you they have front wheels with offset of ET55 and they "work" whereas what they are really saying is that they have satisfied their own personal needs and that is fine. The thing you do not want to discover is that they do not work when you are going sideways at 150 mph!
The 928 front suspension is somewhat unique in the Porsche family in that it is the only vehicle that requires a front wheel offset of ET65 to achieve the NSR [negative scrub radius] Porsche designed into the suspension geometry. I once had a set of reverse spoke wheels from another Porsche model with ET52 up front. They looked great and filled the front wheel well nicely but on autocross duty they were useless- my stock S4 wheels/tyres performed much better and I thought they were crap!
A set of GTS wheels fitted with a 235 up front and a 265 on the rears works reasonably well but if you want real cornering performance they are still below par by today's handling standards. If you do a low mileage you can fit same size but with DOT legal rubber and that improves things. If you want to get the best cornering performance from the car you need wider rubber. Stick a 265 section up front and a 295 rear can be "loose" if you do not have the anti roll characteristics well sorted. To carry this kind of rubber you need custom 3 piece wheels and I reckon the combination I run with is about as good as one is going to get with 9.5 inch x ET68 up front and 10 inch ET60 on the rears. This combination works nicely on the S4 but such wheels do not come cheaply unless you are really fortunate. Wheels of this geometry are typically 3 piece forged alloy made by the likes of Fikse and others.
There is a Porsche OEM wheel either 9 or 9.5 inch wide x 17 with a suitable offset [if you can find them] in the Cup 1 [early GTS] design. The closest I know of in a current Porsche OEM fitment are the Panamera wheels but then they fall short of the mark offset wise and I would not use them unless I had no alternative. That being said many do run with them and are happy with their purchase.
+1 for Panamera 18". The best offsets by far for any stock 18" wheel. The only real alternative is $$$$ 3 piece aftermarket.
Easily available on eBay thanks to Panamera owners wanting 19s/20s, and tons of tires are available from full snow/ice to racing slicks. Best of all, lots of room in the well and no rubbing so no fender rolling needed. I have the 5 spokes with 245/35-18 front, 265/35-18 rear. I am not familiar with the tires you mention, but I use all-season tires (Michelin Pilot Sport AS3+) and love the performance and the look of the tire/wheel combo.
@FredR - I think you're aware of this, but the Panamera offset is 59 vs S4 65, a difference of only 1/4" or so. (In the rear it's 53 vs. 52.5, i.e. negligible.) There is no noticeable difference in turning between stock and Panamera 18s. Your 68/60s are quite different than stock thought they probably behave just fine.
The first question you need to be clear about is "what exactly do you want to achieve"? Many folks talk about wheels "fitting" when in reality they should be talking about wheels "working".
Many will tell you they have front wheels with offset of ET55 and they "work" whereas what they are really saying is that they have satisfied their own personal needs and that is fine. The thing you do not want to discover is that they do not work when you are going sideways at 150 mph!
The 928 front suspension is somewhat unique in the Porsche family in that it is the only vehicle that requires a front wheel offset of ET65 to achieve the NSR [negative scrub radius] Porsche designed into the suspension geometry. I once had a set of reverse spoke wheels from another Porsche model with ET52 up front. They looked great and filled the front wheel well nicely but on autocross duty they were useless- my stock S4 wheels/tyres performed much better and I thought they were crap!
A set of GTS wheels fitted with a 235 up front and a 265 on the rears works reasonably well but if you want real cornering performance they are still below par by today's handling standards. If you do a low mileage you can fit same size but with DOT legal rubber and that improves things. If you want to get the best cornering performance from the car you need wider rubber. Stick a 265 section up front and a 295 rear can be "loose" if you do not have the anti roll characteristics well sorted. To carry this kind of rubber you need custom 3 piece wheels and I reckon the combination I run with is about as good as one is going to get with 9.5 inch x ET68 up front and 10 inch ET60 on the rears. This combination works nicely on the S4 but such wheels do not come cheaply unless you are really fortunate. Wheels of this geometry are typically 3 piece forged alloy made by the likes of Fikse and others.
great points fred! most folks are more interested in form over function, and as long as that is safe, that's fine. like a lot of 928 owners, I am running Carrera lll wheels: 8 x 18 ET 58 up front
with 235/40-18 and 8 x 10 ET 57 with 295/30-18. main reason for this choice is I really like the look, they are a proven fit, AND lots of those wheels around so they won't break the bank.
@FredR - I think you're aware of this, but the Panamera offset is 59 vs S4 65, a difference of only 1/4" or so. (In the rear it's 53 vs. 52.5, i.e. negligible.) There is no noticeable difference in turning between stock and Panamera 18s. Your 68/60s are quite different than stock thought they probably behave just fine.
Ms Stormy Daniels would not notice 1/4 inch but in NSR terms that is a "country mile". Under a stock setup the NSR for the S4 is 10.2mm and "6mm missing" is a large difference. The worst case is probably an offset of ET55 as the Kingpin axis would go straight through the tyre centerline and that creates problems as I experienced with ET52.
The entire point of the NSR is to create stability under certain conditions such as when driving through a puddle on one side of the car. The increased resistance creates a yaw effect and the NSR is designed to create toe in when such events happen- thus why I have often written that going sideways at 100 mph is no time to find out that Porsche knew what they were doing. Talented drivers like Lewis Hamilton might well be able to take advantage of a positive scrub radius but your average plonker needs all the stability Porsche can build into the car given the things that can happen.
My wheels are a perfect adjunct to the 928. Contrary to what you suggest my steering geometry is more or less spot on the Porsche spec for NSR. Wider wheels permit more lateral acceleration and this in turn begs more camber- more camber changes the NSR and thus more offset needed to compensate. As to whether they behave "just fine" I think the trophies from our local modest autocross events speak for themselves- plenty of pissed off twin turbo owners can attest to that. The best witness to the fact is a Porsche works driver who was mentoring a group of us at the Dubai autodrome when it first opened. On a lap of the circuit he was the lead and the rest of us followed behind him. The rules of engagement were no overtaking and the pace would be set by the number 2 car which he would keep in front of in his twin turbo 996. When yours truly was the No 2 car at the end of my lap there was no one in sight behind me and Peter [the German driver] jumped out of his car with his eyes popping out of his head. He was way faster than me on the straights but on the bends I kept coming along side him a little just to let him know I could go past if I wanted to. What happened next had me grinning like a Cheshire cat- "Mein Gott" he said 'Ze 928 cannot handle like that - zat is nein possible- vot haf you done to zat car?". They used markers to position the braking point and the turn in point- I was braking more or less at the "911" turn in point and trail braking. It was so easy it was unreal- that is what the 928 is capable of when it is setup correctly. On the next lap I was at the back of the pack holding back so I could go as fast as possible in the bends. At the end of the [shortened] back straight I turned in doing about 90 mph and ... the brake fluid boiled- I threw the car into a spin and called it a day after the rear wheels got bogged down in the sand as I ran out of tarmac on the edge of the track!
On another occasion I was on a 3 lane highway hammering into a real nice downhill bend- as I entered the bend horror struck- t a water main had bust and the road was covered in water. I jumped on the brakes to bleed some speed and back on the gas as I hit the water- the 928 went through it like it was on rails- had I been on ET55's I reckon I might not have been writing today!
Why on earth anyone would modify these cars to make them less than Porsche designed them is totally beyond me but each to his own!
Thank you for all of the input. I really appreciate it. It's been very helpful.
To clarify my intended uses:
1) Low mileage. In fact, the car hasn't even left my garage in a few years. I plan to use it once or twice a month for local trips.
2) I will probably get it on the autocross track a couple of times a year. I'm not particularly concerned about being at the top of my class with this specific car and will put up with under steer and other relatively less than ideal handling characteristics.
3) I am concerned about aesthetics. I want as wide of tires as I can fit without significant fender rubbing while cornering. I also want the wheels to look good with the car, which is 100% subjective based on my personal preferences (polished metal, narrow spokes preferred).
4) I don't care if my tires wear out fast. I have my own mounting and balancing equipment and have no problem replacing tires as needed.
5) I do my own alignments, so I have no problem adjusting that as needed to get the right setup dialed in. I'll start with factory specs, but am open to adjusting that if its appropriate to better match my wheel configuration and driving habits.
6) I don't ever take this car out if precipitation is predicted or if there is any kind of moisture on the ground. So, the tires don't need to be great in the rain or snow or ice.
My question is....what specific wheels do you recommend that have as close to ideal offsets as possible and fit the tires that I want?
From the above comments, I've gleaned that Panamera wheels are popular, but they don't seem to have wide enough rear wheels to fit the tires that I want. So, I'm hoping that someone with the 9" rear Panamera wheels can comment on whether or not they were able to shoehorn 285 or wider tires onto them and still have good fit and performance. Wouldn't they tend to have more sidewall roll if they are mounted on a narrow wheel than they are designed for?
It also sounds like Carrera III wheels are a great option that I hadn't even considered. I'm definitely going to look into those.
Did I miss any other wheel recommendations? Fred, you mentioned 3 piece wheels by Fikse, but I didn't have any luck finding them. Can you provide more information those wheels? While I would prefer to keep the cost down, I'm willing to spend more if there is an "ideal" wheel combination available.
I tend not to drive too aggressively on the street, but there are the occasional spirited driving opportunities where the road lends itself to that and it is legal and safe. But those are few and far between, so I'm not looking for a street racing monster. Just something that meets my personal desire to have the tire model and widths that make me happy, and performs reasonably well in autocross.
Originally, I had planned to put a supercharger on the car, and then I changed that plan to twin turbos, but ultimately I decided that I'd rather keep the car in its current configuration. Which is with S3 cams and a X-pipe. So it does have a bit more power than stock, but it's nothing crazy.
And, to do it "right" to maximize its handling performance. There are a couple of other similarly scoped projects in the queue ahead of it, but the SLC is something that I really want to build. So, I don't want to go crazy with modifying the 928 and potentially shortening the life of the drivetrain or suspension just to gain a little performance that I may never fully utilize.
Thanks again for all of the input, recommendations, explanations and perspectives.
Go the 928 Specialists website [928GT.com]- there Dave has a selection of Fikse wheels that can be configured for the 928. Not sure what offsets he specifies but they will invariably be similar to mine. The rim sections need to be reasonably solid otherwise one good pot hole will take them out. I suspect Dave will have that covered with his specs.
285's do not work on a 9 inch rim section- too narrow. 10 inch is optimal - 9.5 inch will work.
The Carerra 3 wheels are very nice but have the 57 front offset-so typical of what is commonly available.
Sounds as though for your needs some DOT rubber would work well. Perhaps the chaps in your part of the world can give some recommendations. I have used the Michelin Cup tyres- not cheap but very nice and grippy - they seemed to go off after a year of use- maybe our hot summer tarmac did for them.
Thanks. Even Fikse doesn't list the available offsets on their site, and neither does 928GT. I will contact them to see what they say. It is hard to discount the Carrera wheels based on offset if the Fikse offset is unknown. Anything will be better than the hollow spoke turbo twists that I have now.
As for tires....I am pretty set on the Yokohamas that I listed in my first post
06-04-2018, 01:45 PM
Yet another request for recommendations on wheels
Either way, I can't even put 235's on my current ET50 wheels without exacerbating the fender rub situation, so I need something else. Any suggestions on wheels?
