I am trying to source some Wide 15" rear wheels so i can fit some wide tyres. I need the wheel to go inboard of the hub flange so track does not change.
Hope this makes sense, i also need front wheels in standard size. Does anybody know where i can get some. Thanks

You need to know your existing offset and width, put it in this website: http://www.willtheyfit.com/ and play around with different widths while changing the offset so that the outside stays in the same place.

You will need to make sure that the new rim doesn't fowl suspension components; best trick I have used it to tape a length of hacksaw blade to the inside of the wheel to the new width and spin the wheel.

Once you know what you want width and offset try someone like Compomotive: http://www.comp.co.uk/wheels/wheels.asp?size=motorsport-wheels-15-13 who do a range of styles/widths and offsets.