Rim fitment

traco

Just got a new set of rims, spec sheet says they are for the car and the offsets etc are all correct.

What is not correct is the bore in the alloy, its is larger than the shoulder on teh huib if that makes sense. Pic below for ref. I would say the diameter is about 10mm larger than the original alloys.

They OEM ones have a large chamfer on them and only catch at the lip of tge shoulder on the hub.

My question is - Is this critical as in does this shoulder have to interface with teh rimm perfectly and bare some of teh load or is it all through the bolts?

traco

Sorted - should have known teh Germans wouldm't get it wrong. I had all the boxes stacked up and decided maybe I shoudl open them all, in the very bottom box was a new set of bolts and the spacers.

CJhaughey

FYI, the centre bore carries the load, bolts only provide clamping force.
Glad you got sorted.

rex-x

CJhaughey wrote: »

FYI, the centre bore carries the load, bolts only provide clamping force.
Glad you got sorted.

The centre bored doesn't carry any load, its the friction between the wheel/disc/hub that carries the load, hence why you never use copper grease when putting on wheels

CJhaughey

rex-x wrote: »

The centre bored doesn't carry any load, its the friction between the wheel/disc/hub that carries the load, hence why you never use copper grease when putting on wheels

Why have a centrebore at all then?
The purpose of the centrebore is to take the shearing forces off the wheel bolts so they can exert a clamping force and resist lateral forces.
So it is load carrying, otherwise there would be no need for the filler ring.

rex-x

CJhaughey wrote: »

Why have a centrebore at all then?
The purpose of the centrebore is to take the shearing forces off the wheel bolts so they can exert a clamping force and resist lateral forces.
So it is load carrying, otherwise there would be no need for the filler ring.

I'm afraid you are incorrect. The only purpose the centre bore has is to centre the wheel and reduce vibration. There are many people driving around without the spigot rings, albeit with some vibration.
The entire wheel forces are taken by the friction caused by camping the wheel to the hub

porsche boy

Just reading this thread with interest. My 2 cents us that there are Citroen & Peugeot wheels that don't have a centre bore and are a complete pig to balance....

If the centre bore takes the load then why are spacers made of plastic and not steel?

colm_mcm

The centre bore aligns the wheel in the centre. The force of the wheel nuts in the hubs is huge. It's friction that keeps them on. I'd imagine the hub has a role to play in keeping the wheel centred with exreme forces on the wheel like a crash or hitting something on the road.

CJhaughey

porsche boy wrote: »

Just reading this thread with interest. My 2 cents us that there are Citroen & Peugeot wheels that don't have a centre bore and are a complete pig to balance....

If the centre bore takes the load then why are spacers made of plastic and not steel?

The centrebore does not take 100% of the load of the wheel tyre arrangement.
It stops the bolts taking stress at 90° which they are not designed to take.
Vertical loadings such as hitting potholes and the like will cause a shearing force to be applied to the wheel studs and if there is no material between the hub and the wheel then stud failure can occur.
The material used is generally a high grade PA66 with fibreglass and as such is a very strong and incompressible material.
Steel would be better but in better quality fitments alloy is commonly used.

CJhaughey

http://tires.about.com/od/understanding_wheels/a/hub-centric-vs-lug-centric-wheels.htm
This page explains it well, probably better than I am doing.
This paragraph outlines what I am trying to say but better.

"The lugnuts hold the wheel firmly to the mounting plate, but it is the wheel-to-axle connection that actually holds the weight of the car. This is quite an important distinction, as the lugnuts are designed to handle lateral forces that push the wheel away from the mounting plate. The forces that the hub and center bore connection are designed to withstand – the weight of the car forcing downward and impacts forcing upward – are at right angles to the forces that the lugnuts are designed for."

The Sidewards Man

Charlie your wrong, are you seriously suggesting your depending on pieces of plastic for carrying the load? Forget interweb links now.

CJhaughey

The Sidewards Man wrote: »

Charlie your wrong, are you seriously suggesting your depending on pieces of plastic for carrying the load? Forget interweb links now.

Not the entire load. But the plastic rings do carry some load in the vertical plane.
Otherwise the entire wheel assembly is dependent on the wheel studs being able to take shear loads at 90° which they are not designed to do.
The reason you get vibration with wheels that do not have the rings is because the wheel has moved on the hub surface relative to the centrebore.
Plastic is strong stuff especially in compressive loads, look at Mondeo droplinks

rex-x

CJhaughey wrote: »

Not the entire load. But the plastic rings do carry some load in the vertical plane.
Otherwise the entire wheel assembly is dependent on the wheel studs being able to take shear loads at 90° which they are not designed to do.
The reason you get vibration with wheels that do not have the rings is because the wheel has moved on the hub surface relative to the centrebore.
Plastic is strong stuff especially in compressive loads, look at Mondeo droplinks

They never take any shear forces, they clamp the rim to the hub and the friction of that is what takes the shear forces. Many wheels do not sit flush with the centre bore and havent sheared off for this very reason. Do some more research on it and you will see.

The Sidewards Man

How do wheels stay on trailers, independent suspension ones for e.g. Cj.

traco

Well, wheels are on a few days. No vibrations or balance issues so the plastic did center everything up perfect.

Haven't bounced into any potholes yet but I'm sure it won't be long so we'll see how the plastic takes the impact. It's very solid and took a good smack to pop seat them into each rim. I'm sure they're all certified as GmbH testing is fairly tight on all auto stuff.