The existing bolts from the 18" wheels won't fit. So I now have 4 x ATS Radial 7,5J x 17, 5 x 112,00: ET 50 fitted.

 

So does anyone know what size locking bolts I have to order? I was looking at McGard locking nuts for them.

 

Your help & advice would be greatly appreciated.

I am assuming that they are after market alloys that require conical bolts. If so M14 1.5 x 28mm are the usual VAG size (without spacers). Closest McGard bolts are 28.5mm (27222SU). Did the alloys not come with fitting kit (spigot rings and bolts)?

Spigot rings are plastic inserts that reduce the inside diameter of the hole through the centre of the wheel so that it is a better fit onto the brake disc. Mercedes and VAG use the 5 x 112 pcd so after market alloys allow fitment of spigot rings to adjust the size to either brand.

Yep. But unfortunately I didn't unpack them, my old man unpacked them and took them to the tyre fitters, so I don't know what size the bolts which came with them are.

 

I have asked alloy wheel vendors and they've both said that I should use 27205SU. Which are M14 x 1,5 60° x 32 mm Hex: 17mm. 

 

I have ordered one set from one seller on eBay told me that they'd be here in 3 days, they're now telling me that they won't be here until at least the end of the month so will ask the seller to cancel the order: Another one has said that they are in stock and will be sent tomorrow so should arrive on Saturday, just concerned that I have been given the correct information.