When accelarating over say qtr throttle the car will pull right and the steering wheels will go left and the reverse wil happen when letting off the throtle again. This is most noticible on motorways. Could this be track rod ends?? or coul it be that i have two different tyres on the front??

this on a fiesta btw.

cheers for any input, ive already got some track rod ends and will be fitting them tomorrow. Also have some wheels with matching tyres to try tomorrow aswell , just wanted to hear your thoughts on thisincase it cud be something i aint thought of