Fender clearance.

However you can just fit 23.3 mm offets 15x7 wheels using 225/50 R15 tires on a 87 or 88 944. If you have enough negative they will just fit in fenders.

I know this because years ago we had a 944 spec car running like this. Soon after we changed out rules since it provided a track advantage that only the 87 or 88 cars could match. Now we all run stock track width.

 

Thanks Joe- If it were a bearing problem, I'd give up on these. Looks like I'll get the bat out.

I used to have a Subaru that used a weird offset and any other offset meant new wheel bearing every 7k miles.