Nylasurf

I am in the process of having a set of bespoke wheels made for the 964 NB that may not be everyone's cup of tea, but will fit the ethos of my project. There have been multiple topics on wheel sizes that fit the 964 as well as offsets, but I need a bit of help from the experts in order to make sure that I supply the correct inner wheel dimensions to the company making the wheels.

For the basic specifications I am looking at 17" diameter wheels in widths of 8 inch for the front and 9.5 for the rear (225x45x17 front/ 255x40x17 rear). The measurements that I need assistance with would be inner wheel diameter and spacing to clear 928GTS/993TT discs and calipers up front and RS discs and calipers in the rear.

I am going to have the shop doing the work on my car take some measurements off of one of the cars they have access to (993) but you all may have better recommended clearances than what a factory wheel has.

Thank you in advance...

Nylasurf

I also know that "threads are worthless without pictures" so here is a work-up of the wheel being designed...paying hommage to early 911 steelie...




The wheel is a rough mock-up right now as there are some finer detailing that needs to be done...but it gives you an idea of what I am hoping to accomplish...

I appreciate any and all feedback, both for the design of the wheel as well as clearance/tolerances for the inner barrel.

spartansix

Why are you going with 8 and 9.5 if you're planning to run 225 front and 255 rear? The sidewalls will be stretched with those rim widths; 7.5 and 9 would be perfect for 225 and 255.

Nylasurf

225 mm has a section width of 8.86 inches and 255 has a section width of 10.04...granted the profile of each tire varies (more rounded vs squared profile), but 8 front and 9.5 rear shouldn't be stretching the sidewalls all that much.

I am not tied to the widths and welcome the suggestion. I came up with those sizes based on the multiple threads I have combed through here in the forums and the consensus seemed to be 8 in fronts and between 9-9.5 rear (that was the basis for barrel width). I chose 9.5 as I would go with a slightly wider tire but as the car is C4 matching rolling diameter is more of a concern than the extra 10-20 mm of rear meat.

JJJMCD

So they're supposed to be an homage to these? Cool project!

cobalt

To start you are aware that the 964turbo/928GTS big red/black hat is different than the 993TT. The 993TT hat is 5mm shorter than the 964/928. This will impact the clearance between the caliper face and the inside of the wheel depending on which setup you choose.

Also I am assuming you are speaking of the 993RS rear calipers which use a 322 x 28mm rotor. In order to have the rears work on a 964 trailing arm you will not be able to use the handbrake. There are some who claim to have figured away around this but I still have not seen evidence. A custom hat will be required and using any custom rotors will require some way for the bolts to hold the rotor onto the hat. These bolts will interfere with the handbrake shoes and you will need to machine down or off the tab that is used by the handbrake to center the shoes.

I run 8 ET 52 and 10 ET 61 by 18" 225/265 on my C2. This is stock 3.6Turbo fitment. These work quite well however what are you trying to achieve? Are you looking for standard fitment or that just to the edge of the lip look?

I am posting a picture of my 993TT and 993RS calipers on my track car and a close up of the rear. Not sure if this helps but it might give you an idea.

jpar

It's funny, I was just thinking about this the other day. I wonder how a set of 906 style wheels would look on a 964.

Vegas993

Looks a lot like the New Beetle version.

spartansix

I have both 9" and 9.5" rear wheels for my C4, and the sidewalls on 255 width tires (Continental DW & DWS, Michelin Pilot Sport PS2s, etc) look better on the 9s IMO.

Because the wheel you're paying homage to is from an era where tire sidewalls were more rounded and therefore wider than the rims, I think even a little stretch might look out of place.

911Jetta

Similar...

Posted on Face by Neil Powell @ Ninemeister Porsche with the Porsche Club Wales

Bill Verburg

The wheel company ought to know how to put a wheel together w/o the specifics that you request. Some just cannot make a specific ET w/ a specific width, they are limited to a fixed selection of width and ET.

What you want was used on 964 Cup
8ET52
9.5ET47

I have also seen
8.5ET51 also ET48 these are BBS w/ 0288107ctr

10ET44 also ET51 these are BBS w/ 0288107ctr 2" outer & 8" inner

I also measured a set of 8.5 & 10 in a trailer at WGI so these measurements aren't the best
8.5ET40? 9.5" OA, 3.25" front, 6.25" back
10ET45? 11" OA, 3.75" front, 7.25" back

225-245 tires front and 265 to 275 tires rear

gsxr_fvr

Holy crap that thing is slammed. Looks so sick though..any more pics?

cobalt

There weren't too many choices for 265 x 17's a few years back I now see they are offering a few.

Bill Verburg

the variation is tire sizing and availability is astonishing to me

at one time 265/40 x17 was as widely available as 275/40 x17, then the 265s dried up

when I first went to 17s back in pre- history there was a 275/35 x17 that was perfect for use on 911 or 964 rear, availability only lasted a few years

similar thing happened to 245/45 x16 used to be multiple options now down to 1 or 2 and mostly only race tires