Tires

    You are going to want to use bar tread tires for pulling.  They bite into the ground the best.  The most popular size to pull with is 26X12.00X12.  This means the tire is 26 inches tall, 12 inches wide and fits on a 12 in rim.  Another popular size is 23X10.50X12.  If you are running the 26's you are going to either mak your own rim for the tire or buy an aftermarket rim for pulling.  This is because the tire is too wide for the factory rims.  If you run this tire on the factory rims the tire will be crowned meaning the middle of the tread will be the only thing contacting the ground.  Run about 3 psi of air pressure in the tires.  If you are running 23's you may need a little more air so the rim doesn't spin inside the tire.
    You may want to cut the tread of your tires.  Check your rules firts to make sure you can.  Cutting means you take a grinding wheel for tires to the bars of the tires and give them an edge.  This makes them bite into the ground harder.  Take the grinding wheel and angle all of them back and take some off the front of the lug so it has a "sharp" edge.  The tire should look simmilar to the one below when you are finished.