Bolts, tyre and spigots - advice needed

[JJ]

Evening all.  Please forgive my lack of knowledge but I was wondering if I could tap you up for some advice.

I've bought some 18" BBS CH reps to replace my 18" Monza IIs for the winter period (I seem to have two of the BBS Monza variety and two of the Ronal Monza variety on me car but that's another story!) so I've been trying to get my head round wheel offsets and bolt lengths and stuff with little success!

I understand the Monzas have an offset of ET51 and are 7.5J wide.  The BBS reps have an offset of ET50 and are 8J wide.

My first question is will my OEM wheel bolts be long enough for the reps or do I need to get some longer ones to be on the safe side?  If the latter, what length or will any slightly longer than the OEM ones be alright?  What's the difference in terms of mm or inches between ET51 and ET50?

My other issue is what would the recommended tyre size for the reps be?  My Monzas are shod with 225/40 R18 92W XL all round.  Assuming that's the correct size, I think I'd probably keep the profile height the same but I'm not sure what tread width I need for an 8J wheel?

Lastly, I understand I might need spigots on the reps to stop my world going wobbly.  What dimensions do I need to know in order to er, order some?!

Thanks and cheers.

[Hurdy]

Hi JJ,

I doubt your OEM wheelbolts will be fully up to the job. They will work, but you will most likely have anothe 7.5mm of alloy to put the bolt through before it gets to the hub. To be 100% sure simply put the OEM bolt through the OEM monza when it is off the car and measure how much thread sticks through and then repeat the difference with the BBS rep. Any difference will be the amount of extra thread you'll need on the replacement bolts - simples!

ET51 to ET50 would mean that the alloy would stick out 1mm extra on an alloy of the same width.

You will be okay to use the same width tyre as you do on the 7.5" wide tyre as an 8" tyre.

If you bought alloys new or second hand you should get the spigot rings with them, if not then you'll have to measure the inner diameter of the hole in the alloy and then use that measurement with the 57.1mm of the VW hub - so if the alloy inner ring diameter is 75mm you would need a 75-57.1 spigot.


HTH

[Hurdy]

Oh, the 57.1mm is from memory, so I hope someone on here can confirm

[JJ]

Thanks Hurdy.  That's very helpful.   

[big al]

I have the same wheels, and the guy at the garage did say to get some new bolts, he said you can get away with the ones you have, but best to be on the safe side. Anyone any idea what size bolts to get width wise?