New wheels - help please

UK forum for general and technical discussion about the Z3 roadster
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TaffDaddy
Joined: Sun 15 Aug, 2010 21:32
Posts: 40

  Z3 roadster 1.8 TU
Location: Worcester

New wheels - help please

Post by TaffDaddy »

I am looking for some advice on what I need to consider when buying wheels. My preferred size is 17" but I don't know if all 17" BMW wheels will fit a Z3 or whether there are other considerations that need to be taken into account. I've read posts on hear talking about ET** and offsets and, having no technical knowledge, I am confused :cry: .

The wheels I am looking at have come off an E36 and have 215/45 tyres fitted. My current tyres are 225/45 so does this mean:

1. The rims are not wide enough to fit the car?
2. I could fit wider tyres to maintain the width?
3. To maintain the current position in the wheel arch I would have to fit spacers?

I am sure there are other questions I should be asking but I don't know what they are. :head:

Help!

Taff
Dav
Joined: Sun 08 Aug, 2004 13:53
Posts: 1075

  Z4 roadster 3.0i
Location: Axbridge

Post by Dav »

Where do I start?
Are they BMW wheels if so what style are they? Any pics would help.
What width are they?
What is the ET (offset number) It is stamped on the inside of the wheel. You need an offset in the region of 35 to 45 but the fitment will be dependant on the width of the wheel hence the question.
As for tyres, again it depends on the width of the wheel.
There are other things to consider eg the bore, that is the size of the centre hole but all in all if they were fitted to an E36 there shouldn't be a problem.
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Dav the wheel nut
Frank.A
Joined: Mon 20 Jul, 2009 21:15
Posts: 875

  Z3 roadster 2.8
Location: Twixt York and Hull

Post by Frank.A »

Check out the web site linked below.Select Z3 and compare the wheels suitable, with similar style wheels for different BMW models.Some models noteably 5 series have a larger hub bore size and are unsuitable without using adaptor rings which I would avoid.The second website lists offset ranges and other details.

http://felgenkatalog.auto-treff.com/

http://www.gruppeb.com/BMWwheels/fitments/
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TaffDaddy
Joined: Sun 15 Aug, 2010 21:32
Posts: 40

  Z3 roadster 1.8 TU
Location: Worcester

Post by TaffDaddy »

Thanks for the help guys. :D

The wheels I am looking at are 7.5J with an offset of 52. The wheels came off an E46 and the tyre size is 215/45 and having looked at the link you included, Frank.A, the bore sizes are the same but the ET is H on a Z3 and M on an E46 but I don't know whether this has any negative affects. Would I be right in thinking that the wider offset can be negated but the narrower wheel? :?

I am learning all the time. :rtm:

Cheers,

Taff
seaDog
Joined: Sat 18 Sep, 2010 21:54
Posts: 153

  Not specified
Location: East Yorkshire

Post by seaDog »

With that offset and assuming you currently have standard 16inch wheels with a 46 offset, they will be exactly the same as your current wheels with regards to the distance they come out of the arches but will be 12mm closer to your suspension struts. That is assuming you currently have 7j wheels with a standard ET46 offset.

I think some standard wheels are ET41 on the offset, if they are your current set, then the new wheels would sit 5mm retracted (further in) from the wheel arches and 17mm closer to your suspension struts.

http://www.1010tires.com/WheelOffsetCalculator.asp


Hope that helps

Jas
TaffDaddy
Joined: Sun 15 Aug, 2010 21:32
Posts: 40

  Z3 roadster 1.8 TU
Location: Worcester

Post by TaffDaddy »

After much searching I found the wheels I've been looking for and I'd like help to confirm if they'll fit and how they'll look. The sizes are as follows:

Rim: 17inch
Width: 7.5j
Offset: 20

Having looked at 1010tires.com and assuming that my current style 55 wheels are 7j and et46 this will be 20mm further away from the strut housing and will extend an extra 32mm in the wheel arch.

The tyres currently fitted are 205/45 and I would plan on getting them changed.

Will these fit OK?

Thanks in advance for the help.

Taff
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yalden
Joined: Sun 30 Mar, 2008 18:03
Posts: 1232

  Z3 roadster 3.0i
Location: Devon

Post by yalden »

I just hand checked the calcs you got from 1010tires and they're spot on!
TaffDaddy wrote:Having looked at 1010tires.com and assuming that my current style 55 wheels are 7j and et46 this will be 20mm further away from the strut housing and will extend an extra 32mm in the wheel arch.
Being ET20 I'm guessing they're from a 5-series? In which case you would need spiggot rings to ensure they fit hubcentric, these are easy to come by on eBay or through wheel dealers.

The wheels will fit, but your choice of tyre and ride height will determine whether they catch or not! Big fat tyres will most certainly catch if your car is lowered! What do you plan to fit?

I have a spreadsheet that can compare the two set ups, let me know your existing tyres and what you plan and I'll show you the outcome!
TaffDaddy
Joined: Sun 15 Aug, 2010 21:32
Posts: 40

  Z3 roadster 1.8 TU
Location: Worcester

Post by TaffDaddy »

Thanks for your help Yalden. I am going to discuss it with the financial controller ('er indoors) as the current tyres on the wheels are 205/45 and to get the replaced with decent 215/40 it looks about £100+ per tyre.

The main reason I was looking was that I had a spin a couple of weeks ago and have cracked one of the rears and the stealer quoted me £200 for a replacement :shock: , I was assuming it couldn't be repaired as the rim itself is split.

I will keep looking and see if I can find a set with suitable tyres, so I may give you a shout when I find some if that's OK.

Thanks again,

Taff
billz
Joined: Mon 22 Mar, 2010 20:09
Posts: 1240

  Z4 roadster 3.0si
Location: nottingham

Post by billz »

Dicanio has a nice set of wheels for sale. If you are interested.
bill
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yalden
Joined: Sun 30 Mar, 2008 18:03
Posts: 1232

  Z3 roadster 3.0i
Location: Devon

Post by yalden »

Taff what tyres do you have on your current wheels fitted to the car? I'll do a comparison between that and the new wheels with 215's!
TaffDaddy
Joined: Sun 15 Aug, 2010 21:32
Posts: 40

  Z3 roadster 1.8 TU
Location: Worcester

Post by TaffDaddy »

Bill, I did see Dicanio's wheels. Right price, great condition but not what I was looking for.

Yalden, my current tyres are 225/45R16, great if you could check for me.

Taff
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yalden
Joined: Sun 30 Mar, 2008 18:03
Posts: 1232

  Z3 roadster 3.0i
Location: Devon

Post by yalden »

Taff,

Two quick screenshots, the first comparing your current 16" setup against the new wheels with 205 tyres and the second with the 215 tyres you're considering. You'll note that the wheel widths are 1" greater than the J value you stated above, this is because the J value is measured between the inner beeds, the actual width is larger.

Image

Image

The 215 setup will barely affect your rolling radius and as can be seen, will only protude slightly more than existing! Just check your car to see that you can take the extra 32mm towards the arch! 8-)
TaffDaddy
Joined: Sun 15 Aug, 2010 21:32
Posts: 40

  Z3 roadster 1.8 TU
Location: Worcester

Post by TaffDaddy »

That's really useful, thanks Yalden. The rims are 7.5j not 8.5 but I would assume that this would bring them further into the arch.

I am going to have a look whether there is space today as the guy who is selling them has dropped the price making it more tempting. :?

What's the view of whether a 205 would look too slim? I like the look of the 225 but may have to stick with the existing tyres for a while until I build up some funds.

Taff
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