Don't expect to go onto the Continental website and expect to find tyres listed for the ST1100. Well, the ST1100 is listed, but the website says "There is currently no Continental fitment available for this machine."
Not that surprising really; this German company's ContiRoadAttack tyre was recently named as the official tyre for BMW's.
They do list a tyre which would fit, although it has a slighly lower profile. The 160/60 ZR 17. Available in the ContiForce, ContiMotion, ContiRoadAttack, and ContiRoadAttack 2.
I very much doubt I would be fitting any of these models though; from the very few reviews I've read it seems that the mileage expected is in the region of 6000 - 7000 miles.
For a 110/80 front, there is the Conti-Go. It's a cross-ply tyre though, not a radial. Supposedly it has good grip in all weather conditions.
Do you have any comments regarding Continental tyres?