I picked up an 86 sami and i am wondering if i can run 29x8.5-15lt tsls on it stock? currently has tiny 215s on it

That would be the next size up from a 235 75 15 tire,
you will feel the difference but it should pull them ok
on flat ground, just know you are starting with 60 HP

Wild

ok. i plan later on down the road re-gearing the transfer case with the 3 to 1 kit. so these tires should work ok in gumbo mud of flat ground. good to know. i'm from grand forks, nd. red river valley is flat as can be

you will need to get a small lift or clearance some around the front tires to keep them from rubbing. A 2" shackle lift will work for the least moneybut it is best to get new[longer] shocks to get the most of it. I did this for around $150 will easily clear 29s.

I picked up an 86 sami and i am wondering if i can run 29x8.5-15lt tsls on it stock? currently has tiny 215s on it

They will fit fine.  All you have to do to clear them is to trim the corners off the front bumper.  I run these on 2 of my stock samurais.

When I went from 215's to 235's, I already had about 3 1/2" of lift (SR and OME's). I found my tires rubbed the leaf spring on full turn. I had to change the back space on my rims. I did it on the cheap. I reversed the stock rims. I had to drill new valve stem holes and weld over the old ones. It also took a little grinding on the outside of the rear brake drums and outside edge of the front calipers. The stock lug holes are beveled on both sides but the wagon wheel spokes are slanted out so when you reverse them, they hit the edges of the brake drums and just slightly on the caliper.