BMW changes wheel rims on M4 GT3 after cracks and accidents

BMW Motorsport boss Andreas Roos has revealed that it has ditched the problematic wheel rims supplied by Rimstock in favour of products from German auto parts maker BBS.

While Rimstock filed for bankruptcy last year, which “played a role” in BMW’s decision to swap suppliers, the “technical anomalies and problems that we had at the beginning of 2023” were also key factors in the move to BBS.

Initially, BMW was of the opinion that the issues it encountered with wheel rims had to do with the high demands placed by the Nurburgring Nordschleife. But a cracked wheel rim at Oschersleben that forced factory driver Rene Rast out of last year’s DTM season-opener forced it into a rethink.

Since then, the Bavarian marque has been working on a solution in the background, with the new BBS product now ready to use.

The original idea was to introduce BBS-supplied wheel rims in 2025, coinciding with the upgrade to the BMW M4 GT3 Evo, but the plan was brought forward by a year in response to the problems.

BBS wheel rims were already being used on M4 GT3s raced in Japan’s Super GT series since the debut of the car in 2022, but BMW has further honed the parts as it makes it available across the board this year.

“The current rim that we are driving everywhere this year is based on it,” explained Roos. "It has been further developed in order to be able to bring a very good product onto the market with BBS."

Roos is convinced that the potential rim cracks, which first appeared on the M4 GT3 during the test phase in 2021 but then seemed to be under control, are now a thing of the past.

“Otherwise we wouldn’t bring a new rim into the field,” he said.

"Findings from the Rimstock rim and experiences we gained in Japan have been incorporated, so we are very confident that we are now doing well with this rim."

To bring the new BBS rim to the M4 GT3, BMW had to complete a post-homologation change with the FIA, something that is now common practice in GT3 racing.

It is understood that wheel mounts also had to be adapted in response to the new rims.

The change comes as a relief to BMW’s customer teams, who had been forced to go through a rigorous testing process on race weekends to sort out defective rims.

They have praised BMW for quickly reacting to the problem and finding a solution in such a short span of time, especially with 40 M4 GT3s being sold worldwide since its launch three years ago.

“Hats off, because six months is not a long time when it comes to the topic of supply chains,” said one team member. “In addition, the rims must be made available to everyone by then.”