I just put some BFG All-Terrain 305/65R18's about 2 months ago.

Not immediately, but about a week or so after I installed them I noticed a sound/vibration that appears to be coming from my rear end during turns. It only happens when I take off from a dead stop and make a turn... like if I come to a stop sign and make a turn when I proceed.

My guess is that it's the clutch packs in the rear limited slip differential. Has anyone else with aftermarket tires experienced this problem?

 

The lugs on the BFG treads are much deeper and more aggressive than your typical street tire. It is not uncommon to get some vibration at lower speeds from more aggressive A/T tires and Mud tires. My mud tires on my Dakota use to give me and my passengeres a nice back massage at anything under 7 mph. It could have something to do with the LS, but I would tend to think its more just the aggressive tread

 

Id have to agree, it might be the larger more aggressive tires. You wouldnt happen to have any pics of the 305's would you, thats what im thinking ill put on mine here soon.

 

Going out on a limb here, but...It could be a combo of sorts. First, the stock tires (I'm assuming) probably have shorter sidewalls as opposed to the new 305s. Secondly, you probably have always had a tight LS, meaning that the clutches are slightly engaged. Now, my LS has had problems before with the incorrect amount of friction modifier being added causing both, an open-like rear diff and one that barked the tires in corners. Here's where I throw in the tire difference: the higher sidewalls may actually allow the wheel to move more freely (flexing the sidewall) than the shorter sidewalls on your old tires. Not sure anyone understands what I am typing or not, and I could be full of poo, but a possibly tight LS just might be acting differently on new rubber.