What size tubing?

I am going to make a roll bar and full interior roll cage for my 74 Chevy Stepside. What size tubing should be used for this? Most benders that I have found only bend up to 1 3/4" or 2" tubing. Is 1 3/4" big enough?  

I build various cages and bumpers and rock-sliders and whatever else anyone wants and I don't like using bigger tubing. The reason is that it is harder to make a nice radius for the corners or sharp bends. I would go with the 1 3/4" or smaller.  

Wall thickness is more important that tube diameter. I would lean toward biggest tube that you can bend to radius needed. Bigger tube can be thinner wall and be easier to form. 2 inch 3/16th inch wall would be about bullet proof if braced right and 1/8 in wall 4130 should do too.  

That is true as far as strength but what about weight? You might want to get some 2 1/2 Ton Rockwells to haul it around. The thing is, there is tubing out there that is thinner than 3/16" and smaller in diameter that is alot stronger. There is various ways to go on this and it can be the cheap route or the costly one. I have found that the 1 1/2 DOM tubing to be the most versatile for lighter rigs such as toyotas or jeeps. As for your rig, I have a 74 I plan on fabricating a cage for it too time permitting, I am going to use both sizes- 1 1/2 and 2" .120 wall DOM tubing. I am also going to use some that is 2" OD .250 wall. This subject is always a big stir when it comes to size and wall thickness. I am not criticising you SnoMan so take no offense but everyone thinks they have to have the biggest and the thickest when it comes to this. I have built many cages, rocksliders, bumpers, cargo racks, etc. and that is always the question I am asked is "What sieze should I go with?" And to start up another subject that is asked about the same amount- MIG or TIG weld? It just depends on the parts and what it is for. Most of the cage I will TIG.  Some people will just use what they have and in my opinion, that is okay with me.