Only reason is the forces that are applied to the rims when using all the
power the car has.
The studbolts will have to be torqued to a certain level to get the correct
"counter force".
The bolts on the more powerfull cars would have to be "thicker" than the
less powerfull cars and they do not like that.
And the higher torque will result in a too high stress in the bolt.
It's just a matter of down to earth mechnical enigneering!
For that reason they go to 5 bolts of the same size so they can get 25% more
counter force.

Later on they (and many other car makers as well) have decided to go to 5
bolts for the less powerful models as well for standardisation purposes;
more of the same is cheaper!!

And....... 5 looks more sporty than 4, which certainly has been a reason
too!
--
Ciao from Holland
AlfistaGJ (Gert-Jan)
Alfa red 156 SW 1.8 Madeno tuned (2000)
Golden Montreal 1428700 (1973/4)

"Tom Boltwood" > schreef in bericht
...
> I've just come into some 164 3.0 Super alloys. However, my TSpark is 4
stud
> and the 3.0 was 5 Stud. Stupidly, I assumed that 164s would all have the
> same wheel fixings. I'm a bit of a novice when it comes to wheels, so can
> anyone tell me:
>
> a) why they have different stud patterns on these models
>
> b) if there's anything I can do to get these wheels on my car.
>