rexpontius

I can obtain a set of Mille Miglia Cup II replica's in 18".

While the offset (ET52) for the front's is not ideal, I have a machine shop that can modify them to around ET60 it there is enough 'meat' in the centre.

I searched the forum a bit, but see some posts that the MM's are heavy and soft (easily bent).

I really like the styling, but I'm not waiting for steering wheel judder or other problems caused by low quality wheels.

Has anyone got 1st hand experience with these wheels?

Cheers

jcorenman

Yes, we have those wheels on our GT. The fronts are 8.5" x 18" et52, rears are 10" x 18" et 47.
Tires are Michelen Pilot Sport PS2, 235/40-18 front & 265/35-18 rear.
When we bought this car (Oct 2008) it had 17" Mille Miglia wheels (also ET52 in the front) with Toyo tires. Over the next 60K miles we fitted Sumi HTRzIII's, then the 18" wheels with PS2's about 20K miles ago (mid-2011).

We like them, but the fit is tight and they may not be for everyone. Here is what we found:

Fit: Compared to the GTS size of 7.5" x 17" ET65 front, the extra width here is on the outside-- which means they sit farther out, the edge of the tread is basically in line with the front fender lip. This means no rubbing on the inside (common with wider fronts), but some folks may want more coverage by the fender. We have not found any issues here.
In the rear, the wheel is also outboard compared to stock, no problems on the inside and there is about 1 cm clearance on the fender lip (GT with the factory rolled fender lip).

Offset: The steering axis is neutral (i.e. coincides with the tire center) with an offset of 55, with the stock 25.0" diameter. Generally, 5 to 10mm positive offset is recommended, as it is more stable if one side gets into soft ground (for example ET65), but I believe that more positive offset also makes the steering less responsive.
With these wheels, the ET52 is so close to the 55mm steering axis as to make no difference, IMO. Also, the diameter of the PS2's in that size is 25.4" which moves the steering axis a few mm outboard, matching the wheel offset.
Around here, the biggest wheel/tire-related issue is "tramlining", the tendency of the front tires to follow the "ruts" that are worn in the pavement by idiots driving their studded tires on dry roads (we get about 2 days of snow a year). Wider tires make it worse, but I don't think it is related to offset. What helps is setting the front alignment to the max toe-in allowed by the specification.

Strength: Ours were straight, and still are. Any of the "cup" wheels are cast vs. forged, and are more subject to being bent-- the centers get bent when the rear end smacks a curb (primarily a 911 problem). And we've seen some 993 factory cups that were bent, always the rears. It is something that you should certainly check (and a condition of purchase, if possible), but I don't think the Mille Miglia's are any softer than other cast wheels.

Machining: I would not do that, under any circumstance. If the ET52 offset is not to your liking, then continue looking. There may have been extra "meat" in the center, before the wheels were machined and the mounting holes were bored, but that is gone. If there was still extra material then the lug-nuts would not fully engage, which they do.

Comfort: Wider wheels means lower-profile tires, which means less rubber between the wheel and pavement. Which means, everything else being equal, a harsher ride in exchange for crisper handling- the classic tradeoff. The thing that is not equal is tired, and the Michelins are less harsh than others. Overall, not much different than the 17's, and firmer/harsher than the old stock 16's.

rexpontius

Thanks for your input, i will check the wheels out.

Regarding the offset machining, I have really positive results with this procedure (last month I had them do a set of new OZ superturismo's from et30 to et35)

As long as there is more than 7-8 mm thickness (after machining) in the straight section of the bolt holes, there should be no problem.

Dont know how this looks at the Mille miglias but I will check it out.

Cheers

JWise

I'm glad Jim has had a better experience than me. I'm one of those that has encountered issues with these rims. Note - I'm only using the rear wheels from my set. My fronts are OE Cup II's in 17x9 ET 70, and I've had no issues there.

I bought my replicas from a 993 owner who had become frustrated with their cracking and inability to hold air. I purchased them and had the cracks professionally repaired and then sent to a refinisher for painting. After all that, one of mine still leaks air from along the bead seal. Additionally, even after road force balancing, one of them has excessive run-out resulting in annoying vibration. I love the look, but the quality issues greatly dampen my enthusiasm.

Knowing how easily they crack, I would NOT remove any material in attempts to increase the offset. I don't see how this could do anything but weaken the wheel and possibly present a serious safety hazard.

I'm patiently waiting for Jim Doerr to produce a quality set of these wheels. He's well along the way to bringing 18" phone dials to market, and I'm hoping Cup II's will be next in line.

BTW-there was another member here who used to have a set of these replicas. When I was still looking for a set, I tracked him down to make an offer only to find he no longer had them. He hadn't sold them, either, he put his in the trash. Too many bends and cracks....

S4ordie

I have the same configuration as JArrod on both of my cars. In less than 5,000 miles I have had to repair one rear wheel. This after fully straightening and reconditioning them. They are soft to be sure. They look great though.

rexpontius

You guys convinced me, I Will not take them. It reminds me too much of the troubles I had with Azev 8.5x18 wheels I had on my Alfa Romeo. They bent just by looking at them :-)

dprantl

8.5x18" ET52 wheels with 225/40-18 tires did not work well on the front of my former '86. If you get into the wrong situation (not common, but possible, such as turning towards the same direction the rear is sliding out to), the front tire WILL contact the fender and will damage it.

Dan
'91 928GT S/C 475hp/460lb.ft

rexpontius

Thanks, I will be looking out for some original 9x17's for the rear.

I have 7.5x17 CUP II's on all four corners now, which looks reasonably well with the factory spacers at the rear axle, but I think it will look just a bit better with 9x17's at the rear.

Thanks for all the advice!
cheers

FredR

Porsche designed a premium car which by and large they did not under engineer. As one of the most critical pieces of kit, the wheel tyre combo is something you do not want to get wrong.

If you have a 7.5x17 inch rim on the rear it did not get there courtesy of Herr Ferdinand- and at that size the max section you can run is a 235 [possibly]. Not hard to understand why you might want rid given it can only be suitable for the front if the offset is correct.

Porsche original 928 fitments are Speedline wheels custom specified by Porsche and they are expensive- and not just because the are Porsche pieces of kit. Even GTS wheels can and do yield on crappy road surfaces.

Porsche designed our front suspension systems to give a NSR [neutral scrub radius] of 13mm if I remember correctly. In short this means you need front wheels with the correct offset to achieve this. The stock wheels are ET 65mm [S4 and later]- I believe earlier models are pretty much the same just that the steering components are different. Cheap after market alternatives, probably designed with the 911/Boxster crowd in mind with offsets around 52mm fit in and fill the wheel well nicely but that does not mean they work as Porsche intended.

If all you do is go to the shops and be a good citizen following the speed limits then they "work". Fellow astute headbangers like Dan well know, they do not do so well when pushing the envelope and you need the full brilliance that Porsche designed into our cars to makes them brilliant.

My front wheels are three piece forged, they have an offset of 68mm, 9.5 inches wide and carry a 265x35 section. Your teeth will probably fall out before the front end let's go! Such wheels however typically cost $5k plus and of course circa $1500 for good rubber to go on them.

Bottom line- sad to say - you get what you pay for.

Trust the above helpful- I always recommend stock 928 wheels [GTS] or 3 piece specials made by good manufacturers. Anything less would not really interest me. Needless to say many different opinions on such matters.

jon928se

While I agreee and can't really argue with FredR's sentiments, I do have some contrary thougts.

I've had a set of MM 18" CupIIs on my SE then GT in total for about 8 years and 40,000 miles mostly in Aus but also in NZ (Where I lived up a dirt road 1km from sealed road) and in the UK.

The wheels are still true. This is despote the fact that while Australia tries and mostly fails to outdo every other nation in being bigger and better it does not fail in it's claim to have the biggest potholes and the worst roads.

The difference between appropriate offsets and their effect on Negative Scrub Radius and the alternative can't be argued, it's simple physics. However some of us actually like driviing cars that feel like that. Maybe being brought up on front wheel drive cars has something to do with it. I find the 90GT on it's stock D90 rims somewhat dead to drive.

I wish I still had access to FE software as it would be interesting to see what effect machinging off the inside mounting face of the wheel would have. The best thing is you wouldn't need to know any forces involved or even need to estimate them. The wheels are hubcentric so purely rely on the wheel studs in Tension, thus it would be fairly straightforward, knowing the yield stress of the alloy lug nuts and the wheel to establish an upper limit to the force transmitted through the lug nut threads and then ensure the stresses in the wheel when subject to the same forces remain lower even when machined.

That said If you are giving up on your potential purchase of CupIIs I would be interested in buying some 18x10 CupIIs.

Jadz928

I look forward to the opportunity to clear my plate enough to devote some time to making that happen. Would like to do both the Cup I & II's in 18".

I have an idea for a method to make them alot easier to develop. Possibly easier for someone else to take on, with some guidance.

rexpontius

I know that wheel quality and weight can make or break the total car experience. On my Italian cars I only use OZ racing wheels which work perfect, they are strong and light.

I will try to find a nice set of original wheels so I am sure to get the best experience.

Cherrs

supercedar

that are worn in the pavement by idiots driving their studded tires on dry roads (we get about 2 days of snow a year).
Jim
You have confirmed what I always' thought. I am a idiot!! But my girls come home safe every weekend from the mountains.