Ok I am lowered on Espelirs, have been for about 1.5 months, last week I put on new rims and tires, the problem is the back left tire, IT IS NOT RUBBING on the fender, however upon acceleration the back left wheel is Vibrating badly

If I am at a steady mph it is fine, the second I give it some gas to accelerate it vibrates badly.

I have yet to get an alignment, I dunno if that is the problem. the first day I noticed it, it was a small vibration, I thought it was my tire rubbing when I went WOT and the back end squatted down, but this is not the case

Do you think they botched up the balancing and this is what could be causing it?

I am going to go to the place that put my tires on and ask them in the morning but I want to see if anyone knows what it could be?