Hopefully this will be my last gripe before receiving my vehicles, but what's the deal with tyre pressure monitoring?

My 4.2td is now due for delivery. Rather than order the tdi 20" 5 spoke wheel we opted to the 20" S-line twin spoke design. Dealer has now called me and advised that the tyre pressure monitoring system will not work on these wheels and that I have to revert back to the tdi wheels to get them to work. Having no option, disappointingly, I have agreed to do this.

Anyone know the story behind all this? Does this mean that at a later date I cant upgrade to the 21" rs4 style wheels (currently unavailable in Australia) and have the tyre pressure monitoring functional?

thanks,

B