Hello Eckhard,
> it  seems the wheels are to big ...
this is a TORCS problem:
The ride height needed to drive fast is 100mm ( = min value), but the suspension course is 200 mm!
With nearly all cars, the wheels are to big or the wheel houses are to small (It is just a point of view).
It isn't done if you look at it with the standing car (ride height = initial ride height = 100mm),
you would have to check all possible positions of the wheels.
The ride height decreases with increasing speed (down force).
In addidition the camber and toe values (together with the steering angel) affect the possible positions of the wheels.
You can't just change the wheels, because it would change the balanced carset!
Here the facts from cyclon (as for most other cars):

<attnum name="ride height" min="100" max="300" unit="mm" val="100"/>

<attnum name="toe" min="-5" max="5" unit="deg" val="0"/>

<attnum name="camber" min="-2" max="0" unit="deg" val="-2"/>

<attnum name="suspension course" min="0" max="0.2" unit="m" val="0.2"/>