1/8 or 3/16

im doin my first sfbd on my ranger and i was curious what most people are using for their frame rails? ive seen the purchaseable mandrel bent rails are 1/8" so is that good enough? or should i use 3/16? i dont want to use 1/4" due to the extra weight and it being a little overkill in my opinion but to each his own i guess...anyone got any input?

I use 1/8 on mini's and 3/16 on SUV's and fullsize trucks.   2x3 or taller.  But, I have seen  pieces of 2x2   1/4 thick for rails on an old school datsun hold up as well.

.125" wall is fine if properly designed and engineered.  Those mandrel rails should be fine, most companies that make them do recommend that they are used with a cage.  I don't see it being a problem on a mini though.  I would like to mention that the mandrel bent rails are thinner in areas due to the bends streching the material.

In my oppinion i would use 3/16 tubing. i think you maybe happer in the long run.With 1/8 inch thick rail  your frame may have a tendency to bow or sag very slightly.. escically if its a extended bab or crew cab...

I like using .150 myself. I usually have to order it into the metal yard but delivery is typically a day or two so no biggie. I find a lot of 1/8 tubing seems to have side walls that are bowed out slightly which I find to be a pain when I'm fitting them up. Plus its not to hard to accidently smush it with Bessey clamps if your not careful.

i have always used 3/16" under a cab and 1/8" for the backhalf without any problems.

the stock c channel or boxed frame on most minis is 1/8 or close to it. but, they are alot taller. so, id say 2x3 in 3/16 under the cab or any long areas that arent otherwise supported. 1/8 for the rest shouldnt be a problem. just build it strong and well designed.