Porsche 991 Rear Axle Steering Clearances

The 991 generation of Porsche 911 represented a major leap forward in tech for Stuttgart’s greatest contribution to the sports car lexicon. One such tech innovation that showed up in 2017 as an available option on the second iteration of the 991 (known as the 991.2), was an intuitive rear axle steering (RAS) system. We’ve found when 991 owners with the RAS system optioned on their cars start looking into upgrading to an aftermarket wheel, there’s often a concern about how close the RAS motor gets to the barrel of the new wheel, and particularly so when downsizing from the factory 20” wheel to a 19” setup.

Through various on-car test-fits and laser scans of the 991.2 generation of the 911 Carrera, we’ve found the mounting point of the lower control arm on the wheel upright is the component that gets the closest to the barrel on our 19” wheels. With both our 5-Lug 19x11.5” ET72 and 19x12” ET46 fitments, Apex’s wheel options for the 991.2 clear all of the necessary suspension components, including the RAS motors. This clearance is illustrated in the images below.

On the left, we see a top-down view showing the clearance available between the RAS motor and the barrel of one of our 19” forged Sprint Line wheels. On the right, we see the space between the barrel of the same 19” wheel and the lower control arm mounting locations on the upright. Even during RAS actuation, the RAS motor does not get as close to the lower control arm as it does at its static location. The below photos are of a Carrera T (narrowbody) with our 19x11.5” ET72 VS-5RS, the wheel that brings the barrel closer to the RAS motor than any of our other 19” options. If we consider that same clearance allowance on a widebody car with our 19x12” ET46 fitment, the inner lip actually moves 20mm away from the RAS motor, further improving the amount of space you have. As a byproduct of Apex wheels having a barrel design engineered to provide as much clearance as possible for big brake kits, customers with RAS-equipped 991.2s also have all the space necessary for downsizing to 19”s, which is a great choice for track-focused cars or anyone looking to add a bit more sidewall to their 991.2

Left: Top-down view of RAS motor Right: Lower control arm mounting location

Brandon is a Porsche Fitment Expert at APEX Wheels. Prior to joining APEX in 2022, he worked as Office Manager for a Porsche & Ferrari service and race shop, guiding customers in all areas – suspension, power, aesthetics, you-name-it. His first foray into racing came In college when he was asked to assist at a PCA club race. Says Brandon, “I figured if I am already making the drive, I might as well enter the HPDE happening at the same time.” He hasn't stopped since. Among the various cars he has owned and/or tracked are a ‘74 Corvette Convertible, ’74 Firebird Formula 400, ‘17 GTI, ‘07 Cayman S, and his current ride, a ‘12 Cayman R (BGB X51 pack 3.8L) with staggered APEX EC-7RS 18x9”ET46 & 18x10” ET36 in Motorsport Gold. Fun Fact: Brandon is a big fan of SIM racing, which he uses to learn about a new track he’s going to or get a refresher on a familiar track, as well as improve his racecraft.Have questions about wheels for your Porsche? Use our contact form and ask for Brandon.