There is no MOT requirement regarding date for tyres on private motor vehicles, only on commercial and passenger carrying vehicles such as mini buses and coaches.
TT wheels are perfect on an A2 and the 205/45/16 tyres on them aren't a problem either as with the TT wheels being 7J (7" wide) rather than the standard A2 wheels that are 6J you wouldn't want to have the standard A2 size of 185/50/16 on the wider TT alloys as they would be stretched a little and not really wide enough.
Tyres can be 5 years old and no good or 10 years old and perfect, all depending on how they have been stored, whether they have been kept out of direct sunlight which degrades the rubber compound and not exposed to extreme temperatures.
That said tyres that were manufactured the 48th week of 2007 or even older at 2005 certainly aren't going to be at their best but if they aren't perished where there is cracking evident between the tread and on the sidewalls and shoulders they could just need wearing in again, especially if they are new to the vehicle but if they haven't been stored correctly the rubber could be hard and brittle as others have suggested and be causing the problem.
The oversized 205/50/16 size works well on the TT wheels btw as they give a little more sidewall depth and comfort and oh don't worry about the 83 load rating as that is the lowest you will get that tyre size in, that or 87 and there is nothing wrong with an 83 load rating on an A2. Some popular non A2 sizes that people use on an A2 (185/60/15 for example) are usually only available in an 84 or 88 load rating so 84 would be the one to go for.
Always check the wet rating of a tyre before you buy them, A is best and buy no worse than B as to me that is the most important factor of a tyre and check the noise rating too, obviously the lower the better.
Hope this helps a little?