Top tube is 1"
Bottom inner tubes are 1"
Bottom outer tube is 1.4"
Tubes are 1.9"
Horrible sizes for US standards cus trying to find non costly tube clamps for anything but the 1" tubes is a nightmare...
Only non-costly options are basically to use u-bolts or exhaust clamps. For the 1" tubes, I found an awesome cheap/free alternative walking around the junk yard today - Tie Rod Clamps. Yup, take the 1" clamps and replace the bolt with longer ones that fits your needs and with enough of them, you have yourself something to work with =)