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Wheel, tyre and ETs

Discussion in 'A4/S4 forum(B5 Chassis)' started by ScottD3, Sep 16, 2011.

  1. ScottD3
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    ScottD3 I want your faulty electronics

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    I'm slowly getting my head round wheels and ET but when putting them all together I get a bit confused.
    I've tried reading and looking in to it but for some reason it just does not stick with me.

    I've decided to go for the easier option the option where i'm less likely to get it wrong.

    I'm after a new set of wheels, size wise I'm thinking about 17" or 18", I'm not 100% sure which yet and i'm still trying to find what I like hence theses two posts.
    http://www.audi-sport.net/vb/photography-digital-darkroom/109649-playing-photoshop.html
    http://www.audi-sport.net/vb/a4-s4-forum-b5-chassis/129411-avants-alloy-wheel-picture-thread.html

    Next bit of information I need is recommended width, ET and tyre size.
    I understand width, ET, size and tyre size all dependent on each other and the suspension drop of the car, but can we make a couple of assumptions or is there sort of mathematical working out that can be done?

    Thanks in advance for any advice.
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  2. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    Its a bit of trial and error, and looking at what people have done in the past really.

    Theres obviously a maximum tyre width that fits between the arch and upright, which is around 225 or 235 in width and 40 profile for 18's or 45 profile for 17's

    But said tyre fitting properly depends on the offset, and wheel width. Typically wider rims require you to lower the offset from the OEM ET45, to give clearance on the inside. Lower the offset too much and the wheels start to poke out.

    Then you get into the whole realms of stretch, poke and such nasties, where folk like to persuade wheels that dont actually fit onto their car.

    As a general rule 7-8" wide wheels around ET35 to 40 will fit comfortably within the arch with a 225 wide tyre.

    Go much outside these and you'll start to have issues.
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  3. Jason.s
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    Jason.s Active Member

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  4. Jason.s
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    Jason.s Active Member

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    I bought some B7 17s with a 7.5x17 ET 45. Front cleared the upright fine but the rear was hitting the spring platform on the shock and wiped all the outer wheels weights off so i got a 5mm spacer which took car of it. Planning on getting some 10mm spacers taking them to ET35 to push them out a bit more for looks at some point.
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  5. ScottD3
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    ScottD3 I want your faulty electronics

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    I like the look of stretched but don't think I could ever run them.......may be a little bit of a stretch. lol

    Main thing is to the get the wheel and tyre under with out having any issues.
    I don't really want to buy a set of wheels find out they don't fit and then have to sell them to get some more.
    I did that be my BMW and I hated it.

    I'd like to get the wheels to sit flush the wing, I really like that.

    Whats the general thought of different width wheels on the B5s (or Audis in general)?
    Not that i'm thinking about it just wondering.
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  6. ScottD3
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    ScottD3 I want your faulty electronics

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    8x17 ET35 will fit as well the?

    what about 8x18 ET35?

    Jason, i'm playing that link now. thanks.
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  7. THE MONSTER
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    THE MONSTER Member

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    I have wheels 7.5jx17 ET 45 with 235/45/17 tyres fit great front and back they are really close to the strut on the front but no issues and no spacers needed front or back..
    Last edited: Sep 16, 2011
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  8. mike-a
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    mike-a Member

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    Rim diameter doesn't make a vast difference,it's all about ET and width.Tyres between 215 and 235 will be ok as mist wheels in 17+ inch diameter are going to be at least 7.5" wide.Maybe worth buying cheap spacers to get the wheel/arch combo flush and then use propper steel hubcentric ones once you're happy.
    I've the following on mine: front 225/35 on a 19x8 wheel ET33
    rear 235/35 ,19x8 ET25
    Wheels flush with arches and plenty of clearance all round on OEM sport suspension.
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  9. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    Jason, thats pretty odd.

    Standard B5 S4 wheels are 7.5Jx17 and ET45 so the wheels should fit just fine.
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  10. Jason.s
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    Jason.s Active Member

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    Yeah was a bit strange as i wasnt expecting that. Its not exactly a huge difference to the standard ones apart from diameter but yeah still happened lol.
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  11. jcb
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    jcb Active Member

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    As a self confessed wheel whore I have run 7.5Jx17, 8Jx18 and 8.5jx18
    they have been in offsets from ET45 to ET24
    tyres run include:
    215/45 on 7.5j17
    225/45 on 7.5j17
    235/40 on 8j18ET35 and on 8.5jET24 (current set up)
    245/40 on 8j18 ET35
    245/35 on 8j18 ET35

    I run coilovers with a single finger gap between top of tyre and edge of arch. never had arch rub on any of them but before I fitted the 245/40 ET24 8.5jx18 I had the arches slightly rolled to remove the lip but are no wider than any other standard A4/S4 B5.

    I have never used spacers

    what is more relevant is the tread to side wall transition.
    get a chunky tread tyre and the transition can be bulky and will catch the rear upright (it has less clearance than the front)
    Tyres I have used that work are

    Mich PS2
    GY F1 GSD3
    GY F1 Assym
    Nokian WRG2
    Pirelli P6000 (but please dont consider these as they are dangerous in anything but warm dry track!)

    hope that helps.
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  12. Soupie69uk
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    Soupie69uk Owner

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    I run 2 sets of wheels both with 225/45 tyres:
    7x17 et 45 with 25mm spacers on the rear and 15mm spacers on the front
    7.5x17 et 36 with 13mm spacers on the rear and 5mm spacers on the front

    My car is pretty low and the rears sit pretty flush with the arch at the rear and sit in a tiny bit at the front.
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  13. ScottD3
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    ScottD3 I want your faulty electronics

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    I think I found some I like.
    just want to double check if this work.

    18"x8.5" with a ET35, will the wheel fit with a 235/45/18 tyre?

    Where will the rim of the wheel sit in relation to the arches?


    I really wish I understood this ET thing better, I just can't get my head round it or remember it. lol
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  14. Jason.s
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    Jason.s Active Member

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    From a non-lowered view, Probably pretty damn flush to the arch or even a slight poke. Probably the latter..Which means you might end up with some scrubbing on the arch lip on faster cornering.
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  15. jcb
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    jcb Active Member

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    think you would be better with 235/40 profile.
    I run 8.5J on ET24 and there is a little bit of poke.
    your issue is the clearance on the rear struts, lower profile will be better for that.
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  16. ScottD3
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    ScottD3 I want your faulty electronics

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    Thats just what I'm looking for.

    I got a koni 40mm kit fitted now.
    From a standard SE kit I think its a bout 10-15mm drop.

    I don't drive fast or courner fast any way, so I should be ok.

    Cool, I'll remember that.

    Thanks.
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  17. ScottD3
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    ScottD3 I want your faulty electronics

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    235/40/18 8.5J with ET35.
    Sorted.

    Now I need to sort some storage out for theses.
    Is any one able to messure the complete diamiter for this size of wheel and tyre?
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  18. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    You can calculate it from the tyre dimensions unless you need it milimeter accurate.

    Tyre section X (sidewall profile x2/100) + rim diameter in mm's

    for a 235/40r18:

    (235 x 0.8) + (18*25.4)
    188 + 475.2
    645mm

    Actual dimensions should be within a few mm of that.
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  19. ScottD3
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    ScottD3 I want your faulty electronics

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    Cool. thank you. :)
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  20. ScottD3
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    ScottD3 I want your faulty electronics

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    Ok i'm bringing this back from the dead to bounce some ideas around with you knowledgeable folk.

    random chat and random ideas brought up some questions.

    set of alloys.
    Fronts 19x9 Et33 running 215/35/19
    Rears 19x10 Et30 running 225/35/19

    Chances of theses or some combination of tyres and spaces, fitting on a B5?
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  21. Jason.s
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    Jason.s Active Member

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    Big camber, big stretch, some arch work = dont do it it`ll look sh!t :p
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  22. ScottD3
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    ScottD3 I want your faulty electronics

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    Ahh possible.
    Worth asking the question though :)
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  23. Mackers
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    Mackers Member

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    a quick one, as i have a car show in 10days (short notice i know) i'm looking for 18"x8" wheels fitted with 225/40x18 tyres what offset (ET) do i need.
    Thanks
    Wayne
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  24. ScottD3
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    ScottD3 I want your faulty electronics

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    I'm running ET35 with out any issues.
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  25. Mackers
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    Mackers Member

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    ....damn quite a few have 45 ET :( :(
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