I'm thinking about getting a used set of Fikse FM5's for my '93 GTS on the FS forum.

Here are the sizes:

The front are 18x9 / 51 offset

The rear are 18x11 / 38 offset

I am not good with figuring offsets. I am too stupid.

Will these sizes work? I think the fronts are not good, but what offset is recommended with a 18"x9" front? I can have Fikse change out the front rims to get the offsets right for a 928 GTS.

The rear I can play with using spacers (I think).

 

I'm afraid the fronts will be pushed out a bit much , 7mm more than my car, I have 8.5" fronts with a 52 offset. Click my Avatar for pics. The rears I cannot comment on, but with the GTS you have a lot of room to play with so they'd probably be fine.

Use this calculator for figuring out offsets...


http://www.1010tires.com/WheelOffsetCalculator.asp

 

Just made a call to Fikse. They recommend 63mm offset with 18"x9" on a GTS and 51mm offset with the rear 18"x11".

 

They recommended that offset for the rear... on a GTS? Alot of folks are running the 11" Turbo's on the rear with ET44 (?) with 295's and minimal flarring. Seems to me you should be able to run 11" ET38 on a GTS with 305's all day long. I could be wrong... I don't have Andrew's wheel fitment calc in front of me.

I'm not sure about the fronts... 8" ET51 will rub (on the outside) with anything more the 225's. Will the 9" make it rub on the inside?

 

David,

Ask the guys at Fikse to do a 67mm offset on the front for you. They do a special milling for us to get to that offset and I feel you will like it better.

For the 11" rears I would suggest a 41mm offset IF you are removing the factory spacers (recommended) which will require a stud change. If I recall these are the offsets I got for Roger's GTS along with a few others GTSs and everyone seemed very pleased with the results.

Give me a call if we can help you in conjunction with Fikse to get exactly what you want.

Below are a couple of shots of Greg Schickel's GTS with those sizes/offsets in the Kinesis wheels.

Hope that helps,

 

Gotta stop making posts when sitting at Jeannie's Desk.. sorry for the confusion :-)

 

And I was just about to comment, "so now we see who the real brains are behind the operation."

 

Ha, Ha, obviously that statement is still true anyway...

 

cold-beer 839,

the offset issue needs to address two issues (at least):
1: Will it fit; and
2: Will it perform properly.

On the latter topic, the front offset is by far the most critical. The weissach axle will 'do its stuff' with quite a consierable tolerance for different offsets. OEM rear offset is 52.3mm on all but a few 928s. On all but a select few 928s the OEM front offsets are 65mm (the 'few' being 1989(???) GTs with 60mm all round. (Or was it the Clubsport model?)). Anyway from my experience, and that of colleagues with 928s, front offsets of 57mm (a common after market option) are inclined to tramline, requiring constant and annoying minor steering corrections especially on roads deformed somewhat by heavy trucks. And the lower the offset, the worse the steering and handling.

I think Porsche knew what they were doing with the offset / scrub radius relationship and personally I would not want to pay for front wheels with less than 60mm offsets - and preferrably at least 65mm offset.

Cheers
DaveO

 

DR,

Was that 67mm offset for use with a m 18"x9" front?

Also what size tires does Greg run on those Kinesis wheels in the above pictures?

I currently have 18"x11" rear Carrera III's with a 51mm offset and a 15mm spacer. With that combination the rear studs did not have to be changed.

 

Hi Dave,

Yes, with an 18x9 front.

With the 15mm spacer on there it is possible you didn't run out of threads (I haven't tried that combo). But without a spacer I have found the threads on the stock GTS studs do not go far enough down the stud to bolt up a wheel directly to the hub. As you know those studs were designed for the stock GTS 35mm spacers so they are not threaded all the way to the hub.

 

Yes, with the 15mm spacers I had enough thread remaining on the stud in the lug seat of the wheel. I put open end lugs on, then capped them with the stock closed end lugs. It is not noticable. If I spend the money to get the Fikse FM5's, then I will remove the spacers and replace the studs.

 

Damn Dave...you must be bored as IMO it's tough to improve the look of your car as she is.

 

It looks good with the Carrera III's on, but the Fikse FM5's would look better IMO.