Rear Tire Wear

[Larry's shee]

94 Ranger 4wd, 4.0l, auto. I think it has some type of posi as I cant spinwhen one wheel is jacked up, and when both are off ground both spin same direction.
Problem is that my son seems to be eating up the rear tires. He's not an idiot doing burn outs, thank you.
Opinion as to what to do, is this normal? Would a fluid change with proper friction modifyer help/fix? Or does the posi/ls need rebuild?
Only non stock item is when he bought some used BFGs on Grand Cherokee rims he only swapped the fronts and used the jeeps on rear. Would the little bit difference in wheel offset cause this?
Let me know if any other info is needed.
Thank you for your help !!
BTW, I did search tire wear in this forum and didn't find anything relevent.

 

[disciplerocks]

The L/S would in fact cause them to turn the same direction, unlike an open diff, but it should still be able to turn with one wheel on the ground. It only engages under load. Sounds to me like someone welded the spider gears or it has a spool installed. Which would lock both tires and cause wear from driving on pavement where it can't adjust for turns. Remove the rear cover off and take a gander.

 

[ForOffRoadDriving]

Sounds like something in the tracloc unit is messed up. Kinda like its locked itself together and isnt allowing the outside wheel to spin faster than the inside wheel when turning. Usually after 17 years of use the clutch plates wear out and slip, but it sounds like youre having the opposite problem. its also possible that someone has welded the spiders or installed a spool as disciplerocks said, but you gotta pull the cover to be 100% sure.

 

[F150hybred]

Sounds like something in the tracloc unit is messed up. Kinda like its locked itself together and isnt allowing the outside wheel to spin faster than the inside wheel when turning. Usually after 17 yeqrs of use the clutch plates wear out and slip but it sounds like youre having the opposite problem.

Yanno, some of us here wouldn't see that as a problem!