oze, wow, that is narrow!! Too narrow! IMHO

Yeah you do need some spacers really. Trouble is, 7mm (internal) spacers don't seem all that easy to find. I am lucky in that i had some that Corally used to provide with the 12M wider axle - so i use these. I also use flanged axle bearings, this makes it a little wider due just to the flange!! and also stops the bearing getting punched through the bearing holder in a big crash. My car measures around 171 with Parma wheels and about 0.6mm wider when using GRP wheels.

Although i said 7mm spacers aren't easy to find - i do know that Calandra make some!! I am not sure of the part number, but i have seen them, and i know a couple of guys over here that have some. In the UK you can also get spacers that go between the hub and the wheel - made from carbon fibre. You would obviously need longer screws to use these as well.

Hope this helps a little