pete b wrote:
For nearly 9 years I kept a 993C4 (between 05 and 14) and I recall a post from a chap with an engineering background at Toyota swapping out his wheel bolts because of corrosion. Unfortunately the non-original bolts had been made to a slightly different pattern and were not identical to OE. They failed and the supplier (well known as an OE as well as a parts supplier) discovered a number of really serious shortcomings. I believe that it caused quite a panic - the bolt heads were unable to provide sufficient grip between the wheel and the boss despite being torqued correctly.
I would not use anything other than originals...
The corrosion tends to be caused by the use of alloy wheel cleaners I'm told.
996 uses steel wheel bolts, your 993 was using the alloy wheel nuts as used on the earlier cars, but still best if you stuck to the genuine item.