Speedie; I recently fitted 2 new tyres fitted to the front. Then i decided to put the new tyres on the rear, and thats when i started to notice the car pull to the left. I took the car to get it aligned and found there wasn't any problem. I spoke to a mate in the trade, and he suggested that i swap the front wheels around, I thought he was taking the mick, so i did just that and it made a significant difference. You will have a slight pull to the left anyway which will be down to road cambers. Maybe you could try this???