there could also be a buckeled rim, unbalanced or incorrect balancing.
unbalanced wheels can have a huge effect steering feel. also if they are used tyres they check for camber damage and equal tread wear this may also play a part in how the wheels behave.
also if you had poor grip rubber on the stock wheels these nothing to say they it wasnt out of alignment. better rubber, more track may cause these problems to be more pronounced.
also you still have not said when it pulls one way, under braking, accseleration, constant speed all the time.
havnt hit any gutters lately? a mate hit a gutter and it put hit alignment out by alot streched a castor rod moving the whole lca back. i have massive toe out for some reason on my ke and it dosent seem to have any advers effects for some reason.
