Cup one wheel advice please

[cococola]

Hi I have a 1987 944s and I have the D90 wheels fitted. I would like to replace these with cup one alloy wheels if it is possible.
I have seen a set on ebay and I would be grateful if anyone can advise with if they will fit and do I need spacers or anything else?
many thanks []

 

[Eldavo]

Cup 1 wheels come in a few different flavours, early offset, late offset, different widths, genuine wheels and replica wheels are often different too.

Find out the details of the wheels you’re looking at buying and put the numbers into an online offset calculator like the one on "will they fit”

 

[Nick_USA]

Cup 1 wheels come in a few different flavours, early offset, late offset, different widths, genuine wheels and replica wheels are often different too.

Find out the details of the wheels you’re looking at buying and put the numbers into an online offset calculator like the one on "will they fit”

Re: Online offset calculator, here's one I have used for years: https://www.1010tires.com/Tools/Wheel-Offset-Calculator

Nick

 

[Eldavo]

Also see here for offset info, etc:

http://www.944racing.de/wheelweights.php

 

[cococola]

Thank you all so much for the fabulous information,I have bookmarked for future uses []
So the info that I have found out is that my current D90s are..
7Jx16 ET52.3 FR
7Jx16 ET52.3 RR
..................................
The two sets that I have a fancy for are FR 7.5x17 ET15 AND RR 9x17 ET23
The message that have from the wheel calculator is this...
FR.The outer rim will poke out 43.4mm more than before.
RR.The outer rim will poke out 54.4mm more than before.
..................................
So will I be right in thinking that the replacement wheels will fit the arches nicely without spacers and no rubbing please?

 

[bmnelsc]

... my current D90s are..
7Jx16 ET52.3 FR
7Jx16 ET52.3 RR
..................................
The two sets that I have a fancy for are FR 7.5x17 ET15 AND RR 9x17 ET23
The message that have from the wheel calculator is this...
FR.The outer rim will poke out 43.4mm more than before.
RR.The outer rim will poke out 54.4mm more than before.
..................................
So will I be right in thinking that the replacement wheels will fit the arches nicely without spacers and no rubbing please?

To maintain suspension and steering geometry you want to end up similar offsets to your factory wheels ET52.3. The wheels you are looking at are very short of the factory offset and will upset geometry quite a lot. You will also increase stress on suspension links and bearings. You realize that the rears will stick out more than 2" - I would be very surprised if the wheels don't jam up when the nuts are tightened down never mind rubbing on cornering.
These sound like 911 wheels with these small offsets. See the 944 wheels and offsets in the FAQ section of this form. Note the 65mm offset on the wide front ones which require a 17mm spacer be used to get that offset close to original spec. The rears are a bit less fussy.
See this link for Porsche info regarding 17 wheels on the 944.
https://rennlist.com/forums/924-931-944-951-968-forum/802279-upgrading-to-17-wheels-porsche-bulletin-caster-eccetrics-and-rear-mount-bolts.html
Although 18" wheels are not "permitted" the only reason seems to be the increased loading on suspension components exceeds the design parameters but who knows by how much...

 

[g59tester]

Hi, I've just had a fairly difficult session with cup wheels. I bought a set of wheels very cheaply because the seller didn't really know what he had... although he had been advised that they were suitable for a 944. he'd had them on a T25 VW with 1 " spacers. I knew I was taking a chance but at the price they were it seemed worth it as they were in good nick although encrusted at the back. I was pleasantly surprised to find 944 part numbers on them and bought a set of new Michelin pilots and had them fitted to the rims as the car was elsewhere at the time. Imagine my surprise and that of my local independent when they didn't fit. the fronts would not clear the bearing housing cap. Tony on this forum advised me I needed 5mm spacers. In practice I had to fit 10mm spacers to get them on and they didn't look 'right' in the wheel arch. Result... I got my D90's refurbished and the '944' wheels will be on ebay soon

Advice.... BE CAREFUL

I had a 944 for some 10 years ago and i knew it was a bit of a minefield and fell still into the trap

Eddie
2007 Cayman S
1988 944 Turbo

 

[cococola]

That's such a shame Eddie after going to all of that trouble.I think I will be going down the D90 refurb route aswell,at least we know they will fit with no issues.