Introduction and help request

[Ashenry]

Hi everyone,

My name is Andy and I have the (most of the time) pleasure of owning a 1999 Z3 2.3 in Boston Green. I live in upstate NY and love driving the Z3 in all weather but snow.

I recently bought some new tires to put on some genuine BMW style 18 wheels I got to replace some aftermarket wheels the Z3 originally came with. Problem is the shop that’s mounting the new wheels says the center bore is too small to fit on the front wheel hubs! More perplexing is that the rear hubs are the correct size for the wheels. It seems to me that the wheel hubs on the Z3 are normally the same size front and rear.

Sorry for the question in the intro post, I’m just really confused by this problem.

My sincere greetings to all of you and thanks to anyone who can provide some insight.

 

[t-tony]

Hi Andy, welcome from me near Lincoln, UK. The problem is with the wheels you have acquired, not the car. The hub centre diameters on the car are the same on the fronts and the rears.

Tony.

ps. Unless, of course the front wheels (being aftermarket) were fitted with seperate spigot rings to make them fit the hubs, and the front ones have stuck on the hubs preventing the "new" BMW wheels from fitting?

 

[ExMX5owner]

Welcome from down here too Andy...

 

[Ashenry]

Hi Andy, welcome from me near Lincoln, UK. The problem is with the wheels you have acquired, not the car. The hub centre diameters on the car are the same on the fronts and the rears.

Tony.

ps. Unless, of course the front wheels (being aftermarket) were fitted with seperate spigot rings to make them fit the hubs, and the front ones have stuck on the hubs preventing the "new" BMW wheels from fitting?

Nice to meet you Tony, and thank you very much for your suggestion.

The shop said the center bore of all four of the style 18 wheels is the same. However, the center bore hole of the old aftermarket wheels
is bigger than the BMW wheels. I think (and hope) that you're right that there is a spigot ring on the front wheel hubs that the mechanics just overlooked. I guess I'll find out tomorrow...

Thanks again.

 

[Ashenry]

Welcome from down here too Andy...

Thank you, it's nice to meet you.

 

[Shelly]

 

[Ashenry]

Update: it seems that, unfortunately, that an unnoticed adapter/spigot ring is not the problem. The rear wheel hubs do appear to be larger than the front. The front wheels would possibly fit with a light dremeling to the center bore of the wheel, but I’m at a loss about what to do about the rear wheel hubs.

edit: “…*not* the problem”

 

[t-tony]

I would measure the hub with a digital vernier gauge. A tape measure is definitely not accurate enough. I have never seen any vehicle which has different sized diameter wheel mounting hubs (flange) from front to rear. Other wise you would need 2 different spare wheels. Even if a wheel had been run loose the alloy wheel would wear away faster than the steel drive flange.
Also you should measure it in MM to get the correct size. Imperial measurent will only confuse the issue.

Tony.

 

[t-tony]

I just measured one of my wheels which are off my E89.

Tony.

 

[PHILIP BAXTER]

Hi Andy, and welcome from me in Cardiff.

 

[Ashenry]

Hi Andy, and welcome from me in Cardiff.

Thank you, Philip, nice to meet you.

 

[Ashenry]

I just measured one of my wheels which are off my E89.
View attachment 267335

Tony.

Will do, but I think the bottom line is that the rear wheel hubs are at least somewhat bigger than the ones in the front, despite it making no sense.

 

[Mus Musculus]

Hi Andy, and from Cambridgeshire.

 

[Jack Ratt]

Hello and welcome

 

[hard top]

to the Forum.

 

[Ashenry]

Hi Andy, and from Cambridgeshire.

Hi Mus, thank you, and nice to meet you.

 

[Ashenry]

to the Forum.

Hey there, thank you for the warm welcome!

 

[Ashenry]

Hello and welcome

Hi there Jack, thank you for the welcome. Nice to meet you!

 

[Ashenry]

I bought a jack and jack stands yesterday. My plan is to take the rear wheels off again tomorrow and measure the wheel hubs with calipers. If the rear hubs are indeed bigger, I think I might try a small hub-centric spacer to make the wheels fit. Do you folks have thoughts on that plan?

 

[t-tony]

If they are indeed different sizes, apart from changing the hubs that is your only option. I have hub centric spacers on mine, and had them on my previous Z4 and Z3 before that.

Tony.