When i veer left my front end shakes?

Ok, so when I get to about 60mph and veer towards the left, my front end shakes, but its more of like a jitter, but when i veer towards the right its smooth. I did just recently get my tires rotated, but didn't get them balanced. I don't think its a wheel balance problem but maybe a wheel barring problem, but i dont know that for sure. any help would be great. Thanks!