How do these not fit my vehicle??

As above, the spec will fit your car, just the seller hasnt listed every exact model and year they fit.
 
The standard offset for B5's is 35mm though, so with a 42mm offset, the wheel will be slightly further inset from the guard - ie more towards the centre of the car, or away from the outside (though you're only talking 7mm)

Cheers

Marty