Wheel Offset/Bolts Question

[Tabasco]

Hello everyone,

I've recently bought some new wheels for my car, they are from the same model car but a higher spec version - I've noticed that there is a difference in offset however so I thought I'd ask you lot for some advice.

So my current factory fit alloys are ET49 offset and my new wheels are ET40 offset - which I take it means they'll be 9mm closer to the wheel arch??

Basically what I want to know is, when I fit my new wheels, will I need to get shorter/longer wheel bolts or will the standard ones still be ok? Seen a lot of conflicting views on this so just wondering what you all think. 

Many thanks! 

[Phil H]

Are the newer wheels wider per chance? A wider wheel may have a lower offset so it’s inner edge is the same distance from the suspension - offset is the distance between the mating face of the wheel and the centreline of the rim width. There are times when the US definition (backspace) is more useful for these things!

[Rich]

Nov 5, 2018 19:37:40 GMT Tabasco said:

Hello everyone,

I've recently bought some new wheels for my car, they are from the same model car but a higher spec version - I've noticed that there is a difference in offset however so I thought I'd ask you lot for some advice.

So my current factory fit alloys are ET49 offset and my new wheels are ET40 offset - which I take it means they'll be 9mm closer to the wheel arch??

Basically what I want to know is, when I fit my new wheels, will I need to get shorter/longer wheel bolts or will the standard ones still be ok? Seen a lot of conflicting views on this so just wondering what you all think. 

Many thanks! 

So many questions. What car is it? Does it have alloy wheels currently? What type of head does the bolt currently have, taper, ball, sleeve, flat washer? What type do the new wheels require? Are the centres of the new wheel thicker than the old wheel if both wheel types are alloy?

[fr€$h&m1nt¥]

The most certain way of knowing is to take a current wheel off and push a wheel bolt through it and measure how much thread comes out the other side, then repeat for the new wheel.

As Rich says it all depends on the thickness of the wheel at the wheel bolt recess, just because it's wider doesn't necessarily mean it will need longer bolts. Most common reason for a change in length is going from steel to alloy or other way around.

If you're going alloy to alloy and both OEM on the same model it will probably be the same length bolts.

[Tabasco]

ok guys so the car in question is a Corsa C (should've said in the first place haha - also i know it's not retro but it's my daily).

It's an SXi model and the standard wheels are 15" alloys that are 6J - I have bought some alloys from the Corsa SRi model which are also 6J but 16". The only reason I believe the offset to be different was to clear the bigger brakes fitted to the SRi from the factory. The PCD etc is the same.

So would I be ok to use my standard bolts do you think? Cheers!

[Rich]

Seeing as there is only one type of wheel bolt ever used from factory on ALL types of Corsa C wheel, they will be fine to be fitted with the bolts you already have. Crack on!