Seamless tube

[Bonzo]

Originally Posted by Enoch

Maybe it's because 19mm is the closest to 3/4 inch? If he had 3/4 inch to hand, used that then converted it to metric it would have come out at 19mm.

Yep that's my view too

Wishbones have traditionaly made from 1" & 3/4" tube, probably going way back to the original Lotus 7

As Enoch said, this equates to 25mm & 19mm in metric.

If memory serves me right, the original lo-cost had wishbones made from 1.6mm wall thickness tube !!??

Personaly, I would use the 18mm tube that you have to hand, the wall is certianly thick enough.