Wheel offset / uneven wear

    Hello,


    I was looking at my front tyres and noticed that the outer edges are excessively worn, compared to the rest of the tyre. This is about 7,000 miles since replacing the tyres (Goodyear F1) on to e39 alpina softline wheels (18": 8J-18H2-ET20 with 18" x 235 / 40 tyres)


    It could be that the toe-in is incorrect. Although, the wheels have an et offset of 20 and a 10mm spacer (with hard-alloy concentric shim to match the bore) has been added to bring it back to et 10 of the original 17" BBS wheels. However, I read that the e31 should have an et value of 15-25 ?
    http://www.meeknet.co.uk/e31/t…w_wheel_and_tyre_page.htm)


    Does the e31 have a tendency for uneven wear on front wheels?



    thanks

    If there is a large difference in wear on the edges compared to the rest of the tyre you can be sure the alignment is out with too much toe-in. All of the big BMW's I have had do tend to wear the edges more than the rest of the tyre, but not to any great extent. The offset disparity only affects the wear slightly - obviously the further out (the more negative the offset) the wheel is, the more inner wear you will see due to the extra load put across the linkages. But, as your offset is slightly more inboard than it should be, it should not have any affect.

    Timm is dead right with his answer.
    Anyway for your information, the offset of the stock rims looks like this:


    7,5x16" (FA & RA)--> 15mm


    8x17" (FA & RA) --> 10mm


    9x17" (only RA) --> 19mm


    8x18" (only FA) --> 13mm


    9,5x18" (only RA) --> 25mm


    So I claim you did it right with ET20 + 10mm spacers...


    Danilo

    .


    Das was du heute denkst, wirst du morgen sein.
    Buddha


    .

    I always thought that wear on the outer edges on a BMW was a sign of insufficient camber. That the weight was rolling the outer edge under in turns at factory camber settings.

    It could be that the purpose of your life is only to serve as a warning to others. Mine sometimes feels that way.


    Terry


    1995 840Ci
    1991 850i
    Woodland Washington USA

    I run 9,5" fronts et 0mm and have no outer wear, I also have camber plates and run about -1,4 degrees camber. had this setup for 6 years without problems.


    I think you have either a toe in issue or TA bushing issue.

    -Egil (thats my name)

    1990 850IA Hartge SC
    2012 M550d Touring

    If I misspelled a word it's because I'm Norwegian, so bear with me.

    Thank you for all the reply guys. It appears that I should check the toe-in setting on the front wheels. The steering links (and thrust arms) are new, so hopefully, there won't be any rusty nuts to loosen. I agree with Terry, that the camber can also have a big effect, but as far as I know, it's not adjustable?


    I came across this tech info (attached), which may be useful, as it describes all the suspension set-ups including that of the e31.



    8er.org/forum/index.php?attachment/26189/8er.org/forum/index.php?attachment/26189/

    It is normal to wear the outside of the front tyres due to insufficient camber on the front. BMW have this set at 0.5 degrees neg which is why the cars understeer, which from a manufacturers point of view is safer than oversteer. You can correct this, improving steering, handling and front tyre wear by installing camberplates. The ideal setting for a road car is 1.6 deg neg.

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