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Quick question.

I am considering buying some aftermarket alloy wheels. Current wheels are BMW OE size 8jx18, ET30

Car is a 520D SE

The wheels I am looking at are very slightly wider at 8.5x18, but are available in ET30 or ET35.

 

My question is which offset to go for, ET30 or ET35?

 

TIA 

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17 minutes ago, Chris_91132 said:

Quick question.

I am considering buying some aftermarket alloy wheels. Current wheels are BMW OE size 8jx18, ET30

Car is a 520D SE

The wheels I am looking at are very slightly wider at 8.5x18, but are available in ET30 or ET35.

 

My question is which offset to go for, ET30 or ET35?

 

TIA 

 

Use this website calculator to see how the different wheels affect the geometry of the fit: https://www.willtheyfit.com/

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I have previously used a similar site called wheelsize.com in the past, again a good source of valuable info.

My preference would always be to go for the exact offset for the car, as I think you’ve decided on.

BMW spent a lot of time and money figuring out what that offset should be in the first place for a good reason. It’s surprising just how much difference a few millimetres can make to handling and increased wear, especially when your tyres are a pretty penny to replace ! 

 

Good luck finding your nice new rims  ..........  I always think, subconsciously, they’re the first think you see when you look at a car, good or bad, they make the it and hopefully make you smile   :D  ! 

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3 minutes ago, Rolo said:

I have previously used a similar site called wheelsize.com in the past, again a good source of valuable info.

My preference would always be to go for the exact offset for the car, as I think you’ve decided on.

BMW spent a lot of time and money figuring out what that offset should be in the first place for a good reason. It’s surprising just how much difference a few millimetres can make to handling and increased wear, especially when your tyres are a pretty penny to replace ! 

 

Good luck finding your nice new rims  ..........  I always think, subconsciously, they’re the first think you see when you look at a car, good or bad, they make the it and hopefully make you smile   :D  ! 

 

Rolo

My reason for asking is that the wheels I am interested in are offered in BMW fitment in the two offsets.

Had they also been exactly the same size as the current wheels my question wouldn't have arisen.

But they are 0.5" wider.

I asked the question as I was unsure whether the larger offset would be better with the wider wheel.

(It's my wife's car - she doesn't want me to spend money on wheels....)

Edited by Chris_91132

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Difficult one !

This may help ..... or not !
 

I think , possibly,  that ET35 wheel may be right for a different model ? Could be wrong....

 

I dare say new alloys are lower down the pecking order on your Missus’ spending tree than yours  !  :wacko:

 

 

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It's interesting looking at it further that the OE 8.5x19 & 8.5x20 wheels both have an offset of ET33, ie. greater than the 8" wide wheels.

Maybe ET35 would be the way to go with the 8.5x18 wheels I am looking at?

Edited by Chris_91132

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One of the important things to consider when fitting wider wheels is whether the outside edge of the tyres will foul the wheel arches. The fronts are probably the ones to worry about most on a BMW (if the original spec allows for a staggered set up). You also need to be sure that the inside edges will clear the suspension components.

 

An 8.5j rim is 12.5mm wider than an 8j rim, so if you keep the same offset, then the outside edge of the wider rim will sit 12.5mm further out towards the wheel arch. I would imagine an extra 5mm of offset would work better for the steering geometry, maintaining the centre of the tyre in almost the same position. This would result in the outer rim sitting just 7.5mm further out and the inner rim 5mm further in than the original set up.

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