u got the wrong offset for ur rims (18" too big for the M6 IMO)
and u now find urself in a scenario where u have to modify ur
chassis to fit the wrong rims.
rolling out the fenders simply means bending the metal inside ur
wheel arches to create more room for the protruding tires. in ur
case, since u said u can already see the rims sticking out, i dun
think rolling fenders would help. only way is to change rims with
the correct offset, or cut and modify ur entire fender to
accomodate the rims (kind of like chopping ur toes off to fit a
pair of shoes when u could have gotten the shoes with the rite size
in the 1st place)
there are a few reasons why its stupid to have tires sticking
outside of ur car body. besides the obvious reason that its illegal
to exceed the original dimensions of ur car, there is always the
danger of blowing ur tires/crashing out when u "bottom out" at high
speeds. imagine landing after hitting a bump with passengers loaded
in ur car. the fenders will literally "eat" into ur tires. unless u
telling me metal softer then rubber, i seriously advise u to do
something bout the situation soon.
