Porsche cup 1’s

All things round and their alignment to your direction of travel

Moderators: User administrators, Moderators

Neil2801
Posts: 23
Joined: 16 May 2013, 19:42
80-90 Mem No: 12335
Location: Bristol

Porsche cup 1’s

Post by Neil2801 »

Hi all
I am thinking of putting Porsche cup 1 alloyus on my van.
Wheel sizes are
Front are 6j x 16 ET53
Rear are 8j x 16 ET53
I know i will need adaptors to make these fit, but does anyone know if I will have clearance issues on trailing arms?
Thanks

User avatar
slowcoach
Posts: 1214
Joined: 06 May 2010, 10:23
80-90 Mem No: 8892
Location: West Yorkshire
Contact:

Re: Porsche cup 1’s

Post by slowcoach »

Neil2801 wrote:Hi all
I am thinking of putting Porsche cup 1 alloyus on my van.
Wheel sizes are
Front are 6j x 16 ET53
Rear are 8j x 16 ET53
I know i will need adaptors to make these fit, but does anyone know if I will have clearance issues on trailing arms?
Thanks
8 wide is pretty massive, and with that offset they're going to stick out once you add in the spacers to clear the rear trailing arms. Then would the slider open?
Someone might have done it, but sounds 'problematic'! :-)
===================
1984 TRAKKA Conversion Subaru EJ20 5 Speed

User avatar
T3luestar
Posts: 537
Joined: 07 May 2012, 10:31
80-90 Mem No: 13845
Location: Widnes

Re: Porsche cup 1’s

Post by T3luestar »

I have 8j on the rear (245/45r17 tyre) , with 20mm adapters and 7j up front, with 25mm adapters. Unsure of the ET though.
Image

ash1293
Posts: 446
Joined: 27 Jun 2016, 10:49
80-90 Mem No: 16013
Location: York

Porsche cup 1’s

Post by ash1293 »

slowcoach wrote:with that offset they're going to stick out

It’s the opposite way on.
The lower the ET the more the stick out.

When you add spacers the thickness is subtracted from the wheels ET.

So a ET53 wheel with a 20mm spacer is the equivalent of a ET33 wheel.
1990 1.9DG 34DAT carb Leisuredrive hightop

User avatar
Phillydra
Posts: 84
Joined: 29 May 2020, 06:09
80-90 Mem No: 17194
Location: Felixstowe

Re: Porsche cup 1’s

Post by Phillydra »

T3luestar wrote:I have 8j on the rear (245/45r17 tyre) , with 20mm adapters and 7j up front, with 25mm adapters. Unsure of the ET though.
Image

hows the door clearance, I'm doing a wheel upgrade soon, so this is of great interest to me

User avatar
T3luestar
Posts: 537
Joined: 07 May 2012, 10:31
80-90 Mem No: 13845
Location: Widnes

Re: Porsche cup 1’s

Post by T3luestar »

The door did catch the rear wheel just very slightly and scratched the wheel, hence the reason for changing to the 20mm adapters.

User avatar
Phillydra
Posts: 84
Joined: 29 May 2020, 06:09
80-90 Mem No: 17194
Location: Felixstowe

Re: Porsche cup 1’s

Post by Phillydra »

so I assume you had bigger spacers on there before what were they? 

User avatar
T3luestar
Posts: 537
Joined: 07 May 2012, 10:31
80-90 Mem No: 13845
Location: Widnes

Re: Porsche cup 1’s

Post by T3luestar »

They were 25mm same as the front, but after lowing the van the slight camber made the side door catch the wheel.

Neil2801
Posts: 23
Joined: 16 May 2013, 19:42
80-90 Mem No: 12335
Location: Bristol

Re: Porsche cup 1’s

Post by Neil2801 »

Hi All
Thanks for the info.
Am going with the 20mm spacers - will let you know how it goes & looks........

Torfbus
Posts: 2
Joined: 02 Jun 2020, 16:25
80-90 Mem No: 0

Re: Porsche cup 1’s

Post by Torfbus »

Hi

My first post on this excellent forum!

My (new to me) bus is running Porsche wheels with no spacers:
Rear 8J x 16 ET52.3, tyres 225/55/16
Front 6J x 16 ET52.3 tyres 205/55/16
Sliding door just clears the sidewall (very very close). It's a LHD bus but I don't think that makes a difference? The bus has been lowered so I think the camber helps this. The previous owner told me they are Porsche 944 wheels.

On a side note I really think I need to change the tyres, especially the fronts which have a load index of 91. There is huge wear to the inner tread, and I have just changed the upper wishbone and lower TCA bushes to Powerflex ones to try and reduce this.

I am thinking of 205/65/16 on the fronts, which seems to be a common van size with much higher load indexes, and 225/65/16 rears (ie just swapping from 55 profile to 65). I have checked the tyre size calculator on tacomaworld.com and I reckon these will fit - anyone have any advice/suggestions on this before I take the plunge?

My original plan was to ditch the Porsche wheels and get 15" Mefros but these seem to be sold out now in UK (available in USA for $150 each - ouch!)

I have a long list of things to do to fettle the bus....!

Jonathan

 
1989 T25 Westfalia poptop 2.5 Subaru AAP

ash1293
Posts: 446
Joined: 27 Jun 2016, 10:49
80-90 Mem No: 16013
Location: York

Re: Porsche cup 1’s

Post by ash1293 »

Are you absolutely sure there are no spacers???

Porches 944 are 5x130 so would not fit a T25 without pcd adapter/spacer.
1990 1.9DG 34DAT carb Leisuredrive hightop

Torfbus
Posts: 2
Joined: 02 Jun 2020, 16:25
80-90 Mem No: 0

Re: Porsche cup 1’s

Post by Torfbus »

Hi
You are quite right - apologies for my muppetry. The spacers are older and not shiny, so I didn't notice that they were fixed on to the drum. 25mm spacers.

Any thoughts on my proposed tyre size? 

Thanks!
1989 T25 Westfalia poptop 2.5 Subaru AAP

User avatar
Phillydra
Posts: 84
Joined: 29 May 2020, 06:09
80-90 Mem No: 17194
Location: Felixstowe

Re: Porsche cup 1’s

Post by Phillydra »

So after this conversation and one on a Facebook group where loads of people told me 18's with the right ET wouldn't be a problem, I made a "big" mistake I went and brought some old merc wheels which were  8j 18's  5x112 ET 35, 

they definitely do need spacers 

Image

Image

ash1293
Posts: 446
Joined: 27 Jun 2016, 10:49
80-90 Mem No: 16013
Location: York

Re: Porsche cup 1’s

Post by ash1293 »

You are always best off comparing a new wheels spec to the original 14"

IIRC 14x5.5 with an et of 39?

Now if you stuck with ET 39 but went up to an 8" wide wheel then the rim will stick out AND in a further 1.75".

Dropping to an ET 21 with 8" rim would have the rim stick out approx 2.5" further and 1/2" further in than original.

This website will make it easier to understand and work out what spacer is desirable, Obviously on the rear its a fine balance before you have to start thinking about the sliding door rubbing.

https://www.willtheyfit.com/

 
1990 1.9DG 34DAT carb Leisuredrive hightop

User avatar
silverbullet
Trader
Posts: 13630
Joined: 08 Jun 2009, 09:51
80-90 Mem No: 6908
Location: Surrey Syncronaut #156
Contact:

Re: Porsche cup 1’s

Post by silverbullet »

Its a common fallacy that you have to aim for the original ET. As rims get wider, the ET has to fall, because you can only offset so much tyre "in board" until top wishbone interaction or bodywork fouling becomes a problem, as has been shown with those 18's
ET is just the German abbreviation for "back offset" and is a measure of the difference between the rim centreline and the mounting face, in mm.
In an ideal world, an imaginary line drawn through the top and bottom balljoints down to ground level would pass through the middle of the tyre contact patch.
85 syncro Caravelle twin slider Oettinger T3200E-6
90 SA Microbus supercharged wbx/UN1 project

http://www.025motorsport.com

Post Reply