fitting Porsche 928 Wheels to C3

[GTDriver]

Hi there, new to the forum and a new owner of a 2.0 '90 C3 avant.

I am looking at changing the wheels and understand the offset is quite important.

I would like to fit Porsche 928 rims if this would be possible with PCD adapters.

The wheels are 16" / 7" with an et65 offset. - I will be fitting 20mm pcd adaptors which will brind the offset down to et45.

Would these wheels fit with low profile tyres maybe 195/45/16 ?

[Hacki]

Hi and welcome!

I think you have a bit of a misunderstanding how offsets work. You can never decrease the offset with adapters. If you fit 20mm adapters you'll bring the offset up to 85mm ...

Forget about those wheels, you wont be able to fit them without heavy bodywork modifications, and even then - it'll probably make the car drive like garbage.


There arent many wheels with a 4x108 bolt pattern. I'd recommend you convert your car to a 5x112 bolt pattern. Thats possible with very little effort and increases your choice of wheels significantly.

[GTDriver]

Hi and welcome!

I think you have a bit of a misunderstanding how offsets work. You can never decrease the offset with adapters. If you fit 20mm adapters you'll bring the offset up to 85mm ...

Forget about those wheels, you wont be able to fit them without heavy bodywork modifications, and even then - it'll probably make the car drive like garbage.


There arent many wheels with a 4x108 bolt pattern. I'd recommend you convert your car to a 5x112 bolt pattern. Thats possible with very little effort and increases your choice of wheels significantly.

Apologies, you are correct, my calculations were way off!!

Thanks for the reply

[Bastian]

Those Porsche wheels have a 5*130 bolt pattern. Short of modifying your hubs, you have to use spacers/adapters which will bring your offset to unmanageable proportions as mentioned above. Standard offset for your Audi is 35.
The unusually large offset (necessitated by the 928s racing-bred suspension with top and bottom "A" arms requiring a lot of clearance) required on these cars is the reason why there's very few aftermarket wheels for them, and also explains why they are cheaper than other Porsche wheels on the used market - they basically just fit 928s....
I know someone who bolted on a set of 928 wheels to his RS2 for winter use - where they fit natively - but he said drivability suffered and he took them off after a few days.

[GTDriver]

Those Porsche wheels have a 5*130 bolt pattern. Short of modifying your hubs, you have to use spacers/adapters which will bring your offset to unmanageable proportions as mentioned above. Standard offset for your Audi is 35.
The unusually large offset (necessitated by the 928s racing-bred suspension with top and bottom "A" arms requiring a lot of clearance) required on these cars is the reason why there's very few aftermarket wheels for them, and also explains why they are cheaper than other Porsche wheels on the used market - they basically just fit 928s....
I know someone who bolted on a set of 928 wheels to his RS2 for winter use - where they fit natively - but he said drivability suffered and he took them off after a few days.

Thanks for the explanation.

It seems it is a bad idea to attempt to fit them.

Back to the drawing board then!

[Bastian]

If you have set your mind on these Porsche "design 90" wheels, those were not only available on the 928 but fitted all across he Porsche model lineup back in the day. They all look the same but width and offset varied according to model application. The smallest size available was on the 964 front axle - size 6*16 ET 52 (the rears are 8*16 ET 52 and defnitely won't fit under an Audi 100).See here for an example.
This is the only size I can imagine would work on your Audi 100. The offset will still be somewhat too large with the adapters you need to convert to the bolt pattern, but they should at least fit under the bodywork. 195 tires will fit nicely on those.