BMW 318IS Wheels - Help!! | Technical matters | Back Room Forum

Mon 24 Feb 2003 12:33

BMW 318IS Wheels - Help!! - Matt

Having recently bought an E30 318IS (H reg) with 15 inch alloys and then suffering a rear puncture, I was fairly disheartened to discover that the studs would not "reach" throught the BMW spare wheel to screw into the hub. There are no spacers fitted or anything strange about the spare or the hub. I checked with BMW and the studs are original BMW studs (they only make one size/shape of studs) so why wont the studs work with the BMW spare wheel? Nobody seems to be able to help! One solution i've thought about is that the spare may only fit the front wheels so that the diff isn't ruined by having different size wheels on the rear axle (spare is 14 inch rim with higher profile tyre to compensate) - ie. in the case of a rear puncture you put the spare on the front and the front (15inch)wheel on the rear! SOunds ridiculous and very laborious - can anyone help at all? Any suggestions very much appreciated!!!

Matt

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Mon 24 Feb 2003 12:38

BMW 318IS Wheels - Help!! - blank

Not sure about this, but I presume the spare is steel. Shouldn\'t steel wheels have different nut or studs from alloys? perhaps you need different studs for the spare?

Alternatively, should the car have a 15\" alloy spare, which at some point has been lost/nicked and replaced with any old wheel which doesn\'t actually fit properly?

hth
Andy

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Mon 24 Feb 2003 13:35

BMW 318IS Wheels - Help!! - John S

Matt

I think Andy could be on the right track here. I had a 1990 E30 3 series, and that came with 5 alloy wheels, the spare being identical in size and tyre fitment to the road wheels. My current E36 3 series also has an alloy spare identical to the road wheels, so it seems supplying a matching alloy spare is common BMW practice. If you are absolutely sure the wheel bolts are the genuine article, then almost certainly the spare is 'odd'. If it looks like a BMW wheel it could be one of the many 'replica' wheels on the market. As for the front/rear theory, if the studs won't pass through the wheel, then it won't fit on the front either.

You do need to be absolutely sure about the wheel bolts because, of course, the road wheels could be a set of replacement replicas, and the spare a genuine 14 inch BMW wheel.

Regards

John S

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Tue 25 Feb 2003 13:39

BMW 318IS Wheels - Help!! - Matt

Thanks very much for the help. John is correct - the alloys are replicas but the spare is definitely genuine BMW as are the studs so I still cannot understand how they wont work with each other! I guess the previous owner (who i've tried to contact with no luck!) must have had a fleet of low-loaders ready to pick the car up from the roadside when a puncture occured...

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Thu 6 Mar 2003 19:23

BMW 318IS Wheels - Help!! - Matt

Just to let you know that I've found the problem - alloy wheel spacers which I left on the hub whilst trying to fit the spare. I feel pretty stupid but in my defence they really are difficult to spot when covered in copperease etc! Thanks anyway guys...

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Thu 6 Mar 2003 19:31

BMW 318IS Wheels - Help!! - Dizzy {P}

Reporting back when the solution has been found to a problem is catching on! Many thanks Matt, and let's hope others follow your example.

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Fri 7 Mar 2003 11:22

BMW 318IS Wheels - Help!! - John S

Matt

Thanks for the feedback. Spacers eh? Two thoughts - (1) are they so thick as to prevent the wheels locating on the hub centre? If so, you're relying on the bolts to centre the wheels.
(2) Do they allow sufficient bolt thread to engage on the hub?

Now, I realise the road wheels are replicas and so may have thinner centres than original wheels, so (2) may not be a problem - indeed they may be necessary for clearance with non-standard wheels. However, if they are not absolutely necessary to adapt the wheels to the car, then I believe spacers should be avoided.

Regards

John S

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Fri 7 Mar 2003 12:41

BMW 318IS Wheels - Help!! - Matt

John,

In answer to your very pertinent questions:

1) No the spacers are actually only about 5mm thick but this is enough to stop the studs working with the spare.

2) I can only hope that whoever put the wheels on in the first place knew what they were doing and rely on this. The mechanic in Kwik-Fit yesterday who pointed the spacers out to me didn't suggest that too little thread was engaging.

What are the dangers of using spacers? Many thanks for your usual level of useful comments/suggestions!

Matt

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Fri 7 Mar 2003 13:15

BMW 318IS Wheels - Help!! - John S

Matt

I'm intrigued that 5mm spacers prevent the bolts engaging when the spare (which is believed to be a genuine BMW wheel) is used. This implies that the bolts with the spare engage no more than 5mm of thread, and that isn't enough. I haven't checked, but I'm sure the bolts on my car engage much more than 5mm of thread!

The two comments above are two of the potential dangers, but the key one is that spacers move the wheels out, so changing the effective offset of the wheels. This changes the suspension geometry slightly, can affect handling and steering and will change the loading on the suspension components. They might improve the car visually by moving the wheels out, but the effect of the spacers on handling may well be negative.

It's just possible that the spacers are used to get the offset of the replica wheels right. I believe your car will have about 47mm offset - check the handbook - and the wheel offset may be marked on the wheels. It's extremely difficult to measure!

Regards

John S

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Fri 7 Mar 2003 13:25

BMW 318IS Wheels - Help!! - Matt

I believe that, as you predict, the spacers are merely there to get the offset correct as the wheels don't appear to be to far out - if anything they look quite far in - not great terminology or accuracy but hey! The other thing is that they've clearly been on the car for a long time (maybe all it's life) and haven't caused any obvious suspension/handling damage.

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