OK,

I have never understood ET.. so as I need some wheels I thought I would look into it deeper.

Please can you correct my understanding below if I have got it all wrong.

17"x7......Std WRX fitment. Im informed these are ET 55. (or is it 53??)
17x7.5 ...... width of wheel increased 6mm on each side of the wheel centre line, so perfect ET would be about ET48
17x8 ...... width of wheel increased 12mm on each side of wheel. so ET perfect would now be ET 42


Now my question.
How far off from these ET numbers can you run without causing damage to the bearings or upsetting the handling.??

Iv seen people say they run 17x8 ET38 SO FAR without issues..
handling is *subjective* but bearing damage is not..
is a 5mm incorrect ET going to be wrecking my bearing in a couple of years.. my car is a daily driver. and Iv read stories about bearing failing and needing whole hub to be replaced. £££££

thanks
Vik

 

From my experience and that of talking to a couple of engineers in high end motorsport about this very subject a few years back unless you are going to deviate wildly from the specified offsets you are not going to have an issue with bearing wear. 4mm will not be an issue, but bear in mind when you start altering offsets you have suspension geometry to think about as well as the obvious clearance issues.

If you start going wildly out. like 20mm, then you very possibly could cause wear issues.

 

thanks..
thinking about a ET55 wheel for my WRX which may or may not clear the WRX std calipers...
hence the possible need for 3 to 5mm spacer

 

I wouldn't worry about anything with such small values involved. If you go the spacers route, make sure you get some good quality ones and the correct length of wheel bolt to compensate for the spacer.