Wheels I have are ET 40mm. This is fine for the rear, but the front require ET9.5. So am I right in thinking I need 30mm spacers?

I would agree. The larger the positive ET the less dished they are so you want to push them out hence the spacer.


.... but it is early in the morning and my brain has not warmed up yet so small chance I could be worng.

would you not need a 30.5mm spacer?

I guess, but the .5mm I can get away with!

Anyway as long as I have the right understanding! Thanks guys!

U2U sent as I have a pair of custom made ally hubcentric 25mm ones going spare which might be close enough for what you need?

If you are considering competing in your car, be aware that you are limited to a single spacer of 25mm maximum.

Got em the wrong way round, spacers required on the rear!

Wasnt aware of the spacer issue for competing. Is that 25mm overall track or 25mm either side?