Smiffkid, I've done quite a lot of research into the ADR's associated with wheel construction, because, like you, I couldn't see the reason why a beadlock couldn't be legal, and in short, it depends on the type of beadlock.
There is one big reason, and a smaller reason why bolted rim beadlocks aren't legal. (I'll call the kind of weld on beadlocks many of us run as "bolted rim beadlocks")
The big reason is that they don't retain the bead in the normal way, so they don't seal the tyre in the normal way. Tyres are designed to seal (and be loaded) on the outside face of the bead. That's why the outside face of the bead is smooth, contoured, and shaped to match the profile of the rim. A beadlock seals the tyre on the inside face of the bead. That's not designed to be a sealing surface. It doesn't have a parallel profile to the outside bead, so in a bolted beadlock it's being distorted. Look at the bead bulge on the inside and outside of a mechanically bolted beadlock and you'll see they are often different - the outside bead is "flatter" because the tyre is being distorted by being clamped between two parallel faces.
I'll also comment that the bead bundle on different tyres is different thicknesses, so unlike the bead height and outside profile, the width isn't a critical dimension, so it's possible that not all tyres will work with all rim designs - some would be clamped harder than others, for example.
With a steel beadlock, that's not a problem because we all just crank the bolts up until they stop leaking. However, that means there's actually no limit to how tight the bolts can go (they don't "bottom"), or any real way of aligning the tyre on the rim. (and with steel beadlocks, it's quite possible to bolt the tyre up out of alignment... ask me how I know
) Again, that's contrary to tyre and wheel design, and is never going to get approved.
Some alloy beadlock rims like KMC and Walkers have a rebate that aligns the tyre on the rim, but the design - sealing on the back of the bead- is still an issue.
The end result is that by design, bolted beadlocks aren't sealing or loading the tyre correctly, and therefore are susceptible to distort the tyre and leak.
That's the big problem, and it why a bolted "rim" beadlock has never been approved for road use anywhere.
The smaller problem is that certifying a new rim design for road use is very complex and expensive, and, in australia, involved a testing process such as explosively failing a tyre on the test rim at 80km/h in a test environment. The stuff is $$$$$$, and while there's no doubt a beadlock rim would pass, the test still has to be done.
It might be possible to use a testing procedure in another country (like the US D.O.T or German TUV) that applied here too, but it's going to be pretty expensive regardless and will involve some amount of destructive testing, and from then on, likely batch monitoring of the production process.
Anyway, I said it depends on the type of beadlock, because there are road legal beadlocks.
http://www.moparsupercenter.com/mopar-h ... 55743.html
These are legal(* maybe, see below) for two reasons. One, the tyre is retained and seals exactly like a normal tyre. The beadlock liner could be omitted and the tyre will still work exactly like normal. The bolts that hold the two 1/2's of the rim together are clamping metal to metal, and don't rely on squishing up a bead to seal. The tyre isn't distorted and can't be damaged by the beadlock.
The other reason is that Hutchinson, who make them, sell these rims widely to commercial, military and consumers in the US. The market is big enough, and the cost of each rim high enough, to warrant DOT approval once you move outside of recreational users.
* Note: Whilst I have seen these rims advertised as DOT approved and Legal in Australia - and I've seen them on Jeep dealers cars, I don't know for sure if DOT approval for wheels is automatically converted to ADR approval. It isn't for tyres, because if it was, Swampers would be legal in post 1973 cars here.
If Chrysler in Australia confirmed that those rims were 100% ADR legal here, then there's no reason why some Hutchinson Rock Monster beadlocks couldn't be purchased from the US and approved for use here.
I'm not knocking bolted rim beadlocks, I run them and wouldn't run anything else, just explaining the legality issues as I understand them.
Steve.
PS I'm pretty sure bolted rim beadlocks have been engineer approved in NSW. That tells me more about the engineer process in NSW than it does about the legality of bolted beadlocks.
The justification an engineer might use to pass a rim that has "for offroad use only"
cast into the rim for road use, in the example of KMC's would interest me. Would they pass a car on tractor tyres with "not for highway use" moulded into them?
