NThis is a bi-metallic rim manufactured by Ruote Borrani - Milano (Borrani Wheels - Milan), a branch of Costruzioni Meccaniche Rho, S.p.A. (a.k.a., CMR) since 1961, when the owners of Carlo Borrani, S.p.A., lacking heirs, merged into CMR. Alpina marketed one or more models of this rim, but Ruote Borrani, CMR, and/or other firms also marketed models of this rim for makes and models other than the BMW 2002.
The earliest clearly-dated appearance I have seen of these rims is in a photo of the CMR booth at the 49th Salone Internazionale dell’Automobile, which took place in Torino, Italy from the 1st to the 12th of November, 1967. Medium blue and purple examples of the rim are featured near the center of the CMR booth, the colors, I presume, reflecting an eye-catching presentation, and not actual colors in which the rims were available. The cover of a 1960’s CMR catalogue, which I believe to be dated 1967, also shows an example of the rim, this time identified as a “DIAL 8”. A now well-known marketing photo for Alpina — which I believe dates to ca. 1968 (the track car’s rearview mirror is mounted in the post-1967 location, back from the door’s leading edge, but only a long-neck differential, discontinued early 1969, is shown) — shows a version of the rim, with the center disk painted a dark gray or black and the outer rim painted silver. Thanks to Tom Jones for providing a copy of this photo.
Next, in terms of primary documentation, are a pair of road tests of Alpina-prepared 2002’s. The earlier of these, testing a 2002, appeared in a 1968 edition of Auto Italiana. The later of these, testing a 2002ti, appeared in the December 1969 edition of Motor Rundschau. But the rims remained available from Alpina in April 1972, based on a new 2000tii touring delivered by Alpina to a U.S. customer during that year (this is a well-documented Polaris-metallic version sold during 2016 on B.A.T.). Thus, we have clear evidence of the general rim design being offered from 1967 through 1972, with Alpina versions offered from at least 1968 into 1972.
Although I have used the term "bi-metallic" to describe these rims, there is doubt in my mind regarding which two metals "bi-metallic" refers to. Neither the center disk nor the barrel is magnetic, suggesting that neither component is steel. Only the rivets holding the two components together appear to be steel. So why were these rims manufactured as two-piece rims and assembled with rivets by the factory? (A.) Two different alloys? (B.) Simply because Borrani has a long history of, and experience with, manufacturing bi-metallic rims -- many of which were, admittedly, a combination of steel and aluminum alloys? (C.) Could casting the rims as two pieces permit them to be lighter than a typical alloy rim, which is cast in a single piece? They are, indeed, lightweight, virtually “magnesium alloy light”! (D.) Was a two-piece rim simply within the manufacturing capability of Borrani while a single-piece aluminum casting was not? Or (E.) Was there another reason altogether for the riveted construction?
There are at least five models: R1/468, R1/470, R1/472, R1/476, and R1/508. Are we missing additional models? Two of the identified models, R1/468 and R1/470, are 13” x 5”. The other three models, R1/472, R1/476, and R1/508, are 13” x 5.5”. The differences among the five models, besides rim width, appear to relate to (a.) lug nut pattern (PCD), (b.) offset (ET), and (c.) either center bore diameter or, at minimum, the shape of the aperature for fitting a center cap.
The sole example of an R1/468 I've come across lists the PCD as 4 x 98, a common Fiat PCD. I have no estimate of ET. The sole example of an R1/470 I’ve come across lists the rim as “suitable for Opel and BMW 1600/2002”, so presumably a 4 x 100 PCD. I have no estimate of ET. A set of R1/472 rims I own had a PCD of 4 x 98, and a measured ET of 39. A set of R1/476 rims owned by another forum member has a PCD of 4 x 100 and a measured ET of 28. Lastly, a single example of an R1/508 I own has a PCD of 4 x 100, and a measured ET of 20.
In addition, I've seen photos of late 1960's Lancias with what appeared to be the same style of rim. I'm guessing they had a 4 x 130 PCD. Further, a Facebook listing, now lacking a photo, describes a Borrani R1/508 with a 4 x 130 PCD, intended for a Lancia or a 2002ti! It seems clear to me, from the little I know thus far, that CMR was offering these rims for a range of car brands and models, in a range of widths. Would Alpina, for instance, have been selling both 5" and 5.5" versions of this rim for the BMW 2002 market? I don't know for certain, but before you answer "NO", recall that the Alpina/CMR steelie (13", round cutouts) was available from Alpina in two models: the 5" R1-439 and the 5.5" R1-440. As I learn more, I'll try to report it here.
Photos below show an example of an R1/472. The last two photos contrast an R1/472 (right) with an R1/508 (left).