Carpentry and Woodworking - Table Saw Blade Teeth

Building a sofa table for my sister and the legs are going to be ripped from a 1 3/4" x 4" x 66" piece of red oak. What is the best blade (or number of teeth) to use for ripcuts? Someone told me for crosscuts, the higher the number, the better because you were cutting against the grain. Is the opposite true for ripcuts?

Generally speaking, the more teeth, the smoother the cut, rip or cross.

Oak will test your blade when ripping, so I would use an aggressive blade for my primary cut. Using a fine blade will just create heat and burn the wood. If your cut is only going to be 1 1/2" deep, then you may be ok with a finer blade, but if cutting the 4" dimension use the aggressive blade.

Making sure the wood runs true against the fence, the blade is sharp, and proper speed and consistency when cutting will matter greatly. It may be worthwhile making some practice cuts with other wood to be sure that the cuts will work well. If you rip a piece of poplar and have burn marks, blade marks, or binding then you can make the adjustments necessary to avoid this when cutting the oak. Be sure that you don't cut at a rate that overloads the saw. Managing the power available for this task is important, too.

I use a 40 tooth blade for almost everything, so purely the number of teeth is not the whole story.

I agree, a 40 tooth should be sufficient. When ripping a long piece of hardwood, I always use a splitter mounted behind the blade. It reduces binding, and chance of kickback.