cerbera wheels on wedge
Discussion
Hi all, couldn't find a definative answer to the question 'do Cerbera wheels fit a wedge?' so I bought some and did some work....
My car is a series 2 350i. The Cerb wheels have 245 45 16 rear and 225 50 16 fronts.
Issue 1:
Wedge PCD is 112, Cerb is 114.3
You'll need some PCD variance nuts. These just allow the collar of the nut to float and so seat correctly in the wheel and keep the force of the nut parallel to the wheel hub.
Issue 2:
The spigot size is different- this is a saftey issue. The spigot carries the weight of the car, NOT the wheel nuts!
Wedge is 63.4 and the cerb is ?? (see below).
You'll need spigot adaptors. Having access to a lathe and not being a fan of the plastic ones available I made my own.
I found that the cerb wheels already had a spigot ring in them. I removed this and was left with a 78mm by 6.5mm recess in the wheel for the new ring.
New spigot rings: Inner bore 63.5 (+.05 -0), outer bore 77.95 (+0 -.05), thickness 6.45mm (+0 -.05)
I also opted to include a 5mm shoulder on the rings to hold the wheel spacer on the rear wheels (see below).
Issue 3: (on my car, with my tyre combination)
The rear tyres are 245 45 16. These touched the rear tie bars.
You'll need wheel spacers. I used 5mm but this really doesn't leave enough clearance. I'd suggest 7mm, or reduce the tyre size to say, 225 50 16?
Issue 3b:
The rear wheel studs end up a bit short.
I suggest you remove the old wheel studs and fit some 10mm longer ones. I haven't done this yet but I assume they're just the press in type and can probably be changed without removing the hub.
The result:
There's no vibration, the steering doesn't feel any heavier (certainly not once you're moving).
Hope this is usefull to somebody out there.
I took some photos of the process so if people think it will be usefull I'll post them.
Andy
My car is a series 2 350i. The Cerb wheels have 245 45 16 rear and 225 50 16 fronts.
Issue 1:
Wedge PCD is 112, Cerb is 114.3
You'll need some PCD variance nuts. These just allow the collar of the nut to float and so seat correctly in the wheel and keep the force of the nut parallel to the wheel hub.
Issue 2:
The spigot size is different- this is a saftey issue. The spigot carries the weight of the car, NOT the wheel nuts!
Wedge is 63.4 and the cerb is ?? (see below).
You'll need spigot adaptors. Having access to a lathe and not being a fan of the plastic ones available I made my own.
I found that the cerb wheels already had a spigot ring in them. I removed this and was left with a 78mm by 6.5mm recess in the wheel for the new ring.
New spigot rings: Inner bore 63.5 (+.05 -0), outer bore 77.95 (+0 -.05), thickness 6.45mm (+0 -.05)
I also opted to include a 5mm shoulder on the rings to hold the wheel spacer on the rear wheels (see below).
Issue 3: (on my car, with my tyre combination)
The rear tyres are 245 45 16. These touched the rear tie bars.
You'll need wheel spacers. I used 5mm but this really doesn't leave enough clearance. I'd suggest 7mm, or reduce the tyre size to say, 225 50 16?
Issue 3b:
The rear wheel studs end up a bit short.
I suggest you remove the old wheel studs and fit some 10mm longer ones. I haven't done this yet but I assume they're just the press in type and can probably be changed without removing the hub.
The result:
There's no vibration, the steering doesn't feel any heavier (certainly not once you're moving).
Hope this is usefull to somebody out there.
I took some photos of the process so if people think it will be usefull I'll post them.
Andy
Thanks for the feedback- still a work in progress. I take your point about the nuts, but reason that the force is being taken correctly by the stud and nut so I'm confident that it's safe.
I forgot to actually note the ET of the Cerb wheels- I think the front and rear are different, as as far as I'm aware it's the fronts that have to be correct (has a lot to do with suspension/ steering geometry Vs center of tyre contact patch). Though pushing the rear wheels out from the intended position could put more stress on stuff like studs, nuts, etc.
I've noticed that now the suspension has settled (always takes a little drive to do this) the clearance to the tie bar is ok- though a full droop it's probably tight.
Will post more as we go. Remeber anyone reading this- take note of all the other posts, there could be some stuff I'm saying or doing that's just plain wrong!
I forgot to actually note the ET of the Cerb wheels- I think the front and rear are different, as as far as I'm aware it's the fronts that have to be correct (has a lot to do with suspension/ steering geometry Vs center of tyre contact patch). Though pushing the rear wheels out from the intended position could put more stress on stuff like studs, nuts, etc.
I've noticed that now the suspension has settled (always takes a little drive to do this) the clearance to the tie bar is ok- though a full droop it's probably tight.
Will post more as we go. Remeber anyone reading this- take note of all the other posts, there could be some stuff I'm saying or doing that's just plain wrong!
Mine's really smooth with these 16s on, I've started at 24psi and I'm running (afaik) standard shocks/springs. My guess is you're running very low profile 17s? Pehaps my sidewalls are just a bit more flexible?
I'll have to pop one off again to check the width. 7 1/4J did seem a little odd to me!
I've compared them to pictures of other cerb wheels and they look identical, so I'd be interested to see what people think they came off of... ?
I'll have to pop one off again to check the width. 7 1/4J did seem a little odd to me!
I've compared them to pictures of other cerb wheels and they look identical, so I'd be interested to see what people think they came off of... ?
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