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Junkyard Wheel, Wrong Size! :(

Posted: Mon Feb 24, 2020 10:37 am
by eNate
Wanting to have a spare wheel on hand, I ordered up a 10-spoke 428 "cyclone" wheel off a wrecked i3 from my friendly online auto dismantler.

It was delivered over the weekend and I just unwrapped it.

Good news is it looks nearly perfect, and unexpectedly came with a tire mounted, in great shape with plenty of tread left.

Bad news is it's BMW p/n 6856895 which is the 5.5" rear wheel, with a 175 Ecopia mounted. I want to be able to use this as a spare in all four positions.

I understand that when the rear wheel is mounted to the front, something sometimes rubs something.

But in reality is it the tire, not the wheel, that rubs? Can I swap on one of my 155 tires and be OK?

I've found reference that the front 5Jx19 wheel has an ET43 offset, but I can't find an offset listing for the 5.5Jx19. Is it also ET43?

I see that the i3s 5.5Jx20 is ET33, but I suspect that's unique to the Sport.

My suspicion is as long as the lip of the rim clears the strut, a 155 tire on the 5.5 wheel ought to work with no clearance problems.

Image

Re: Junkyard Wheel, Wrong Size! :(

Posted: Mon Feb 24, 2020 3:02 pm
by electronchaser
not really a bummer if you can find one more 175 and then use one of the old 155 fronts as an all around spare. But yes a 10mm spacer will keep from contact on full lock of steering wheel. The spacers are highly recommended. After fitting 15mm spacers at each corner I found every aspect of the suspension improved. From less roll in turns, to more stability when I pass a 18wheeler/cross winds, to less bounce when going over poorly paved roads.

Personally I'd go 175s all around. with a 155 spare. (take up a few lbs and inches less space as well)

Re: Junkyard Wheel, Wrong Size! :(

Posted: Tue Feb 25, 2020 5:41 am
by joni3s
The inside of the rim should have the number, where it says 5.5Jx19, there should be soon a trailing IS number. that is the ET IIRC

Re: Junkyard Wheel, Wrong Size! :(

Posted: Thu Feb 27, 2020 8:07 pm
by eNate
joni3s wrote:
Tue Feb 25, 2020 5:41 am

The inside of the rim should have the number, where it says 5.5Jx19, there should be soon a trailing IS number. that is the ET IIRC

Thank you Jon! I didn't know about the 'IS' notation for offset.

So it turns out the rear is designated 53mm offset, so 10mm deeper than a front wheel (43mm offset).

Combined with the additional ½" rim width, this pencils out to the inner rim lip being 16.4mm closer to... whatever (usually the strut). The face of the wheel slides in about 3.6mm.

Equally importantly, if I mount a 155 tire to the 5.5 wheel, and mount it up front, the tread ought to shift inward about 10mm, and the sidewall will have to make up the 6.4mm difference to where the bead seats against the lip of the rim.

So now all I have to do is measure my current clearances, and if that looks reasonable, find a 155 to mount up and check it out.

Although, frankly, I'd rather this guy sends me the wheel he advertised!

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Re: Junkyard Wheel, Wrong Size! :(

Posted: Sat Feb 29, 2020 4:47 pm
by eNate
I took a gander at the layout behind my i3 front wheel. I didn't have my calipers to get a truly accurate measurement of the available clearances, so I improvised. My measurements are approximate, not precise.

Doesn't look good!

It appears the stock setup (5.0" wheel with 43mm offset) provides 12mm of clearance between the lip of the rim and the strut, as depicted in the photo below.

This means I'd definitely need at minimum a 5mm spacer to take away from the 16.4mm inset of the rear rim mounted in this position, and although my measurements aren't exact, this would be perhaps be too close for comfort.

The other concern is that the coils reduce that clearance even further. The coils are clear of the rim, but could contact the tire, depending on how the front 155 tire fits to the wider rear 5.5" wheel.

This guy at the wrecking yard where I ordered from is ghosting me, so I'm not too hopeful I'll get the correct wheel (I may dispute the credit card charge, which is entirely another matter). So I may be stuck making do with this wheel. I want to get this resolved before I start dismounting tires and scavenging 155 tires to mount up. I can't test fit the wheel up front until the 175 rubber is removed.

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Re: Junkyard Wheel, Wrong Size! :(

Posted: Sat Feb 29, 2020 6:27 pm
by jadnashuanh
Keep in mind that as your air pressure may change or you hit a bump, the sidewalls will bulge out a bit. So, depends on how far you let it get, or how big of a bump you hit.

Somewhere on the forum, there's someone who had some service work done, and they installed a rear tire on the front...trashed the tire within a couple of blocks. Got new tires out of it, though!

Re: Junkyard Wheel, Wrong Size! :(

Posted: Tue Mar 03, 2020 12:05 pm
by KarlC
eNate wrote:
Mon Feb 24, 2020 10:37 am
Wanting to have a spare wheel on hand, I ordered up a 10-spoke 428 "cyclone" wheel off a wrecked i3 from my friendly online auto dismantler.

It was delivered over the weekend and I just unwrapped it.

Good news is it looks nearly perfect, and unexpectedly came with a tire mounted, in great shape with plenty of tread left.

Bad news is it's BMW p/n 6856895 which is the 5.5" rear wheel, with a 175 Ecopia mounted. I want to be able to use this as a spare in all four positions.

I understand that when the rear wheel is mounted to the front, something sometimes rubs something.

But in reality is it the tire, not the wheel, that rubs? Can I swap on one of my 155 tires and be OK?

I've found reference that the front 5Jx19 wheel has an ET43 offset, but I can't find an offset listing for the 5.5Jx19. Is it also ET43?

I see that the i3s 5.5Jx20 is ET33, but I suspect that's unique to the Sport.

My suspicion is as long as the lip of the rim clears the strut, a 155 tire on the 5.5 wheel ought to work with no clearance problems.
I may have an extra 5" wheel that I would trade for your 5 1/2" wheel if you wanted.

Thx Karl

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Re: Junkyard Wheel, Wrong Size! :(

Posted: Tue Mar 03, 2020 12:32 pm
by eNate
Is this the 428 "cyclone" style? You say in your sig you're running 20? I'm 19.

I got the seller on the phone yesterday. He was going to call me back, but of course he didn't. Must have missed my emails, too.

Re: Junkyard Wheel, Wrong Size! :(

Posted: Tue Mar 03, 2020 6:16 pm
by KarlC
eNate wrote:
Tue Mar 03, 2020 12:32 pm
Is this the 428 "cyclone" style? You say in your sig you're running 20? I'm 19.

I got the seller on the phone yesterday. He was going to call me back, but of course he didn't. Must have missed my emails, too.
I have some 428 19" wheels now and 4 - 20" wheels I will be welling soon.

So yes I will have an extra 5x19 428 wheel if you want to trade

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Re: Junkyard Wheel, Wrong Size! :(

Posted: Tue Mar 10, 2020 1:07 pm
by eNate
Good news! I been in contact with the salvage yard and they're shipping me the correct wheel.

Rear wheel is gone!