the V6 models had a stabilizer bar, the V6 Supercharged a 16mm, and the V8s a 17mm bar. A standard three-channel Bosch 5.3 anti-lock braking system (ABS) was fitted across the range, with front discs measuring in diameter (and thickness), while the rear's respective sizes were . Tyre sizes varied from 15-inch P205/65 for the Commodore Executive, Acclaim and Berlina (the latter, and following models, with alloy wheels), to 16-inch P215/60 for the Calais and P225/50 for the Commodore S, and the largest P235/45 on 17-inch wheels for the Commodore SS. For the steering, the predominant system was a variable-ratio Bishop-design design (modified to provide of rack travel per pinion revolution against the VS' , and a kerb to kerb turning circle for the sedan). The Calais, instead, adopted a speed sensitive "Variotronic" mechanism, criticized for its overall feel. This and other new electronic systems (such as traction control standard on the Commodore Acclaim and the Calais, and all optional on all other models; to headlights that automatically extinguished themselves some time after parking and the Calais' key-based memory settings) were possible thanks to a multiplex communication bus. This setup was able to circulate 330 parameters per second to the car's major control modules, and reduce the number of hardwired circuits than if it had conventional wiring throughout (with the VT-series Calais featuring 73 fewer against the VS equivalent). Anti-theft devices included an improved electronic immobiliser (with an extra 16 million codes compared to the VS'), stronger steering lock and latest slip-type locks throughout. Inside, more than 90 percent of the VT's electrical and HVAC components were new over the VS, except for the carry-over column stalks. Safety wise, Holden relied on more computer simulations than ever before (with the aid of crash research from the Monash University Accident Research Centre), resulting in only 20 VTs being physically crash tested, compared to 55 with the previous VR series. A driver side airbag was standard across all models, along with a passenger side optional only on the Commodore Executive and S. Side airbags with torso and head protection became an option for the Acclaim and higher models from 1998 (a first for Holden and Australian manufactured vehicles). Models The VT series was officially announced on 26 August 1997 and went on sale on 5 September replacing the VS Commodore. Its only major update, marketed as the VT Series II, was launched