MichaelC

Hi all,

I have been following this forum attentively and am still searching for the "perfect" rim for my A6. I've noticed that companies like BBS offer 1 piece and 2 piece versions of the same rim (ex: BBS RX and BBS RXII). The two piece are always more expensive. Besides maybe looking cooler, what are the advantages of a 2 piece rims that justify their substantially higher prices?

Thanks,
Mike

MichaelC

And is strength of a rim like the BBS RX really of great concern?

James R.

most people who drive their cars on the street hardly even measure their tire pressure more than once in a blue moon (myself every week or two)...so 2 piece wheels could be bad in that respect.

Regards,

James R.

Cameron

<center><img src="https://www.audiworld.com/news/00/vortrag/white_side.jpg"></center><p>My experience with multipiece wheels:

I had O.Z. Racing multipiece wheels on my A4 with titanium fasteners.

I have three-piece summer wheels on my present car, but am running single-piece wheels right now.

There's a myriad of reasons to go with a two- or three-piece wheel. Some of them are:

1) strength

Two-piece wheels are stronger and last longer in tough use. Wheels are expected to bear the weight of the car, but also bear the forward pending mass of the car on impact. This means any time you touch the curb, or the edge of the track, or that lip near the wall, your wheels take serious stress. The fatigue life of two- and three-piece wheels is signficantly longer.

2) damage

If the wheel becomes damaged from impact, it will most likely damage the barrel and not the face. Two-piece wheels can be repaired with the replacement of one of the two pieces which is always cheaper than buying a new one piece wheel of equivalent quality and weight. If the wheel becomes damaged cosmetically, from abrasion or from curbs, the user can replace only the face.

3) Custom barrels

Custom barrels can be constructed to give widths that would customarily be unavailable where it would be impractical to cast four custom wheels for your car but it is not particularly costly to have four custom barrels C&C'd to fit your existing faces. This is useful when trying to fit extreme tire fitments under restrictive bodywork, or when trying to get the maximum usable rim width allowed by the class or body rulebook.

4) Custom faces

Custom faces allow for the user to achieve a specific offset and/or specific backspacing. This is good for applications with wide caliper bodies and for applications where a specific offset is needed +/- 0.8mm (for example) to both clear the caliper and have the tire line clear the bodywork under lateral load and under compression by an acceptable margin. This also allows a custom design, or custom bolt pattern to fit racing hubs, or locking/latching attachment methods, or to adapt if the wheel's stock face is not available for your car's bolt pattern. The BBS LM two-piece, for example, has several different face combinations available to accomedate the best offsets for the GTS, RT/10, ACR, GT2, and the GenI and GenII Viper variants - this allows the best applications for each car in each class structure (Euro Touring, Drag, Challenge Series, T1, GTS, etc.) There is also a three-piece forged wheel produced in the LM, which I believe is still only available directly to race teams from BBS. It uses the single-lug locking hub. O.Z. offers a similar set of wheels for the F355 cars used in the various European series and subject to differing rulebooks.

5) Appearance

Some people like the look of a multipiece wheel and don't care about the strength or versatility. They buy the multipiece wheel because it's available and more expensive and fewer people have them - hence they must be better wheels, this buyer reasons. Probably 90% of the multipiece wheels not sold to teams are sold due to this motive and none of the reasons stated above.

You want my opinion? I don't want bent rims. I don't particularly like the looks of the multipiece rim and, honestly, cleaning brake dust off two dozen titanium fasteners isn't my afternoon in paradise. However, after subjecting those O.Z. rims on my A4 to hour after hour of tough driving, they haven't had a single problem. Kudos to O.Z. I'm sure any other top wheel company, however (BBS, for example), produces equally high-quality wheels.

Eddie from TireRack may have something to add on the issues I've passed over here, but overall there are many advantages to the multipiece design, either two-piece with face and barrel or three-piece, with face, barrel, and ring. In my opinion, these advantages far outweigh the initial price penalty, though I recognize that for some buyers the trade-off up front in price may not be a worthwhile one.

Cameron

ErikR

The typical center-forged, pressed/extruded lip design has the advantages of (everything Cameron says), but they are substantially weaker than either a forged lip (1-2-3 element) or a cast lip (1 element wheel). The lip in this case is just thin metal. Now it IS lighter, but bends more easily. This is NOT really a problem.

A cast lip wheel will just shatter or bend with a substantial crack (most alloys). This is a very bad thing in a crash. The pressed/extruded lip will bend (taking up energy) and may even keep the tire inflated.

A forged lip is typically a bit heavier, but has better bending resistance and the benefits of the pressed/extruded lip (depending on the metalurgy).

This creates the circumstances for argument about the street use of the BBS rims (for example). They are very light for a street rim, but the lips get bent on bad roads. So, they've even put a second rim protector to try and eliminate nicks and other stress risers.

If you have good roads and don't get extreme diameters (the tire is an excellent rim protector), you will be fine. If your roads are bad and you have lots of money get the forged/forged.

In reality, most rims are way over-designed. So as long as you don't get big diameter rims you will be fine. The exceptions to this are some old ronals that shattered when they hit curbs (so common that Consumers warns about it), and a couple BBS's that bent like noodles.

There are lots of good rims out there. Audi even had all-forged aluminmum ("cookie cutters" for the 5ktq), I have a set and really like them. I recently sold a couple of cast 14" japanese rally rims that didn't even bend in a 60 mph off-road jump.

Chad

Tell me more specifically about the BBS RX II it's design & strenth

ErikR

Way out of the local price range. Nobody here has them. Lots of the vw bbs's 2pieces around, loved by the track racers, not used on the street.

Chad

What's local to you anyway?

ErikR

Western Montana. Home of Ford pickups, muscle cars, 20,000 green subaru wagons, and a couple hundred Audis.