If I were to have some wheels that needed approx. 20mm spacers are there any problems or things I should be aware of ?
Thanks,
Ian

Just make sure you get hubcentric spacers and youve fitted extended studs/bolts accordingly. I ran them for two years front and back and on track days with no issues. If you've got Ford fittings, I've got a pair of 16mm 4x108 with 63.4mm centre bore.

One of my old radical race cars ran a spacer on the fronts to clear the calipers,with no issues at all

I have 25mm spacers at the rear, no issues. You may find you go through wheel bearings a bit quicker though (I had to replace one recently, maybe related, maybe not).

Great Thanks guys

Drop me a u2u if you want a set making. We custom make bolt on wheel spacers (and slot on) to your specs. Can make them with different inner and outer centre bores and PCDs if needed. Www.freakyparts.co.uk for examples