depends what size diameter the wheels are. i think the standard gtir alloys are something like 42-45, but they say the bigger the wheels, the smaller the offset number.
i have 7x17's with an offset of 38 and there is no scrubbing/fouling anywhere.
its not so much the arches but the suspension. my 17's sit litterally about 2mm from the body of the shock absorbers (standard suspension) and they are only 7" wide. if your pulsar has coilovers then you might be ok, cos you do get more clearance on the suspension. like i said its just trial and error