I ran a 26x10 on an 8" rim and had pretty bad walk on the big end running low 12s. One thing that made it alot better was when I quit trying to correct for it, steering it only made it worse. Oddly enough nitrous was a great fix for the problem, I guess it kept the tires wadded up for longer and helped out with the stability.

I never had any issues on the street with a radial front bias rear combo. I don't think I would want a bias ply front on the road, if the back end follows ruts and wanders(which it does sometimes) I sure as heck don't want the whole car doing that.

You also might check your toe settings, if its toed out a little it might wander around some and exagurate your problem.