The company that I use offers the large diameter and small walls. i.e. 101.6x1.6 or 90x1.6, but I agree with Wouter when he reccomends sticking with the 80x2 reccomended.

See

http://www.worcester-aluminium.com/html/rt7.htm

Also the material to ask for is 6082-T6, you may find that the larger diameter/thinner wall is not available in that spec as it is often more decorative than structural.

All the best

Gareth