Could be all manner of things, most tramlining is caused by a particular make of tyre, some are terrible to some don't do it, if you have different tyres on the rear to front why not swap and see if the problem changes then you know it's the tyres, could always toe out a tad more, what is it at at the moment ?
You could also try a few psi more/less in the tyres to see if it improves.
If you want the absolute best grip you need twin tyre wheels, but makers shied away from this due to liability issues, two tyres on each rim at the front was monstrously better grip wis, pity it had real potential.
tabetha