GMP - Matthew

Yeah I think your mis-understood what this form is for and it allows us to do. Once this form is filled out by at least one person with this car, we can then figure out how wide of wheel we can build for the front and rear. What the final offset of said wheel would be. What size outer lips you can use and etc... At the end of the day we can build you whatever you want, if it will fit is another question and the reason why I will still always request each new classic Porsche owner to fill one of these out if they are interested in these wheels is because Porsche did not build all the 928's the same. They didn't build all the 930's the same and etc.. and on top of that some of these cars may or may not have been modified by the owner or the previous owner. So in order for us to our job correctly and ensure you get a great set of wheels that fit

dcrasta

@ GMP-Matthew-

No offense, but I think what you are missing is that no matter what car its for, a wheel with the specified offset [et-65 in a 8-8.5 inch wide 18 inch wheel] is just that. Doesn't matter what car its for, The question was if it would be available in the specified offsets and diameters. Filling out forms and all to answer that question makes you seem more like a salesman and less of a technician.

FWIW - 928s came from the factory with Front offsets of -ET-65 and the majority of Porsche wheels (say 911 etc) come in front offsets of ET-55 or so . These wheels do not fit our cars properly and change the scrub radius (among other things) and we desire wheels closest to et-65 (Fronts) that we can get. Simple question.

#porschewheeloffset

Lizard928

I understand what both parties are saying.

GMP wants each person to fill out the form as no two cars are the same, and they want to guarantee fitments.

however they dont realize that the 928 group knows what offsets work on our cars extremely well. They dont seem to be acknowledging that we want to just tell them what offset we want without filling out all their paperwork.

Matthew,
If you were willing to sell the rims with X offset, you would be getting more business from these guys.
But that said, most people here are not going to be willing to spend this money on these sets of rims too.

GMP - Matthew

No offense taken, but if I also was a technician I wouldn't be on here advertising products. I'm on here because I'm a sales person because that is who I am. I'm not trying to pretend someone I'm not and by providing forms to fill is does not seem like anything other than someone who is trying to be thorough in his work.

So assuming we could build any wheel from the center disc choices above in any width and offset what is the width of the factory Porsche wheel you are referring to with the E65.

Lizard928

The factory wheel with that offset is 7" wide.

However they would want 8+"

GMP - Matthew

Thanks for that info. I just have one more question. If the factory wheel is ET65 and 7.0 inches wide, and you want a wheel that is 8 inches wide with the same offset, again "assuming" we can build an ET65 center disc, there still has to be enough room between the wheel and the suspension and or the outer edge of the wheel and the fender to increase the wheel to a full 8' inches wide, otherwise the wheel is not going to fit which is where the fitment guide comes into place.

I will work on the ET65 on my end if you guys want to lookinto the room available in the wheel house for me.

dprantl

Matthew,

The above are the widths/offsets that would be useful for most 928's. It would be good if you could work on those to see if they are viable.

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

Aspkiller

When it came time to find a wheel that would hold up to track and open road racing, I went with Forgeline ZX3Rs. My reasoning was that if Tim and Cheryl Dey were using them at 209mph +, given Tim's level of research and prep, they would be good enough for me, too. My first set had 9.5s on the front with a 65 ET. Max for that wheel design is 72 ET. Just do the math. 1/2" more or less wheel width equals 5.35 more or less ET. Max on a 9" is about 67 ET, on an 8 it would be about 55. Most two and three piece wheels max out at about the same place. Just a function of the design. Porsche 928 wheels are forged or cast one piece. Whole different ballgame.

Two 9.5 x 18 and two 12 x 18 Forgelines cost me $3,400, plus shipping. Pretty good price, considering.

dprantl

I thought Kibort was running 3-piece wheels in the front that were 10" wide and over 70mm offset?

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

White Lightnin'

Matthew, there is a fundamental difference between 928 owners and the average owners of new Porsches... namely, being a die-hard enthusiast.

Your 'tech form' is set up for those owners that have the factory wheels on their car -and the measurements obtained from that setup. The 928 owner that still has the factory-issued wheels on their car is more likely to be keeping it this way [stock] -and will not be buying your wheels.

The other faction of the 928 camp selects and buys wheels for a number of reasons, being aesthetics or performance or both... and has already done the research as to what fits and what doesn't.

Perhaps you can check with Stephen about putting a disclaimer on wheel orders that eliminate the option of returning them due to fitment issues [which is why I think you are pressing the use of your measurement form]. Let the buyer choose the specs and they pay in advance and they own them regardless of whether their specs are 'listed in the book' or not. They would be non-returnable for fitment issues, but returnable for other reasons like construction or material failure.

The wheels I use shouldn't really work on a 928 according to the 'book'... but with 4 years running and no issues, one has to wonder about the validity of the 'book specs':

Victor Equipment LeMans wheels w/ factory colored center caps (Michelin Pilot Sport 2 tires):

18 x 8 [ET45] (225-40-18) in front; 18 x 11 [ET52] (295-30-18) in rear... the 928 wasn't on the fitment chart -had to use 911 widebody fitment IIRC.

NO spacers!

Vilhuer

That is exactly the problem. All these 3 piece wheels have some specific center piece to which inner and outer ring is bolted to. This means 8", 8.5" and 9" wide wheel all have some width specific max ET which cannot be exceeded without designing different shape center. Which is not going to happed cheaply. Thats why I asked what is max ET for each width. If its too small for out use there really is no point in taking measurements which will tell if wheels will fit around brake calipers or not.

We know 9" wide will fit at front, at least with non stock smaller diameter generic springs some of us use. Tires will obviously rub to body at full lock but that can be handled with wider steering rack stops so its non issue no matter how wide wheels are used. Only real problem is how large front wheel ET is available. Factory used 8x16 ET60 at front. That is used by some of us as benchmark for how far out wheel outer rim can come to. This means 8.5" wheel must have ET67 or it will come further out than factory '89 GT wheel. Same thing with 9". I think ET must be 74 or very close to it. if not, it will not work properly. Most aftermarket wheels have too small ET as they are made for generic Porsche use. 8" ET52 and 8.5" ET56 is basically max values for anything available fairly cheaply. When $$$$ is spend at least I would want ET's to be exacly right. In many cases thats impossible even with custom 3 piece wheels. RH 3.6 Speedline replica is good example of this.

At rear stock ET is in more normal range, brakes are usually smaller and there really isn't similar problem. Only when wheels are 10" or wider ET becomes really critical and has to be within few mm. And this is only in those applications where ET is fairly small. All large ET wheels can easily be handled with spacers.

8" ET45 might work with 225 but try puting 245 into it. While it somewhat works with narrow tire I think it just looks plain silly sticking out too much. There really is no point in having 8" for 225 tire when 7.5" can be used with it. Wheel width alone is not the goal. Goal is to be able to put max width tire to each corner. At front this requires 8.5" or wider wheel with really large ET.

BC

Baring the issues with steering lock-to-lock rubbing, you could put a 10" wheel in front if its over 70mm offset. IF you somehow moved in the sway bar it would probably work.

hacker-pschorr

Jim Page has 10" front's with 305/30-18 tires and the big blue DEVEK sway bar.

Negative camber has been increased and he's using steering stops on the rack. Body is stock except for rolled fenders.

Sorry, do not know the offset.

James Bailey

If you go with what most people who sell wheels think will fit.....they are not going to be very wide

Aspkiller

Lot's of "wrong" wheels work "with no issues", at least perceived issues. But, are you keeping the contact patch optimized?

In a race setup-a few things can be done to change the geometry on a 928 front end. Making those changes will change the optimum ET. I know it's sacrilage to suggest that the 928 front suspension stinks when it comes to adjustability, but IMO, it does.