I've read a lot of tabs for this song but it seems like all of them have atleast one little problem in them...here's what i think

Standard Tuning

The Opening Riff x9                                                      

l-------------------------------------------
l--4-0----4-0----4-0----4-0----4-0----0-----
l-------2------2------2------2------2-------
l-------------------------------------------

End of Riff x1

l------------------------------------
l--4-0-----4-0-----4-0---------------
l------2-------2--------22-11-00-----
l--------------------------------3/--


Main Riff (played alot)

l---------------------------------------------------------
l---------------------------------------------------------
l---------------------------------------------------------
l--2----2-----0-2-x-x-2----0-2-x-x-2----0-2-x-x-3-2-0-----


Fill from the main riff (listen for when he plays it)

l----------------------------------------------------------------
l----------------------------------------------------------------
l---------------------------------0-2-3-2-0----------------------
l--2----2------0-2-x-x-2----0-2-------------0-2-3-5-3-2-0--------


What is played during verse (play a lot)

l-----------------------------------
l-----------------------------------
l--2222222222222222222--1111-0000---
l-----------------------------------

he starts off the verse with the opening riff 
but when it slows down he just hits his 2nd fret on the 
A....there are some riff 
variations 
that i prolly missed that u can figure out urself if u want....
i havent gotten down 
the thing he does during the bridge cuz he 
doesnt keep a specific pattern with 
the riff if u listen....sorry if this didnt 
help....if it did cool..
.oh and one more thing...SMOKE WEED!