It depends on how much wear you have. I had a rear changed at approx 3000 miles without any problem. I had a front need replacing at about 6000 and the dealer measured the wear and told me I would have to replace both.I got a slow puncture in a rear tyre having done 6,000 miles and replaced the tyre.
A friend told me that I needed to change the other rear tyre as Quattros need both tyres on an axle changing at the same time.
It would really veer if you did that! The widths are significantly different. Check the pressures and then the tread depths to ensure that they are not significantly different ...either could cause the problem.Just had a thought. What if I swapped the new tyre in the back with one from the front? Do you think this will make a difference? I'd rather not spend the extra £300 yet - esp if it isn't what's causing my veering problem...