Continental's website doesn't have the Conti Twins listed anymore, you may be able to find some at a dealer in your area, but be mindful of the age of the tire.
There is a date of manufacture molded into the sidewall of the tire it will be a 4 digit number like 4907, that would denote the tire was made in the 49 th week of 2007.
You don't want old tires.
You don't have too many choices for tires in the Metzeler line, the Lasertec tires seem to be a popular choice for the BMW airhead bikes.
I have used Metzeler ME33/ME99, now the Lasertec series, since around 1987 or 1988, can't quite remember.
They are great tires for dry, warm conditions, I reside in Phoenix and the tires perform excellently in hot conditions, but when it gets cold ( for Phoenix !) below 45 F. they take a while to warm up and 'act right', if you ask too much of them before this, you're likely to get a nasty surprise.
I don't get to ride in too much in wet conditions, but the few times that I did, they weren't confidence inspiring, and the roads in Phoenix get pretty slick with a first rainfall in months , and usually I'm in rush hour 'death cruise' commute, so I'm overly paranoid as well.
So someone else with more experience in wet conditions may have a different experience.
Average life is about 12-13,000 miles (20-21,000 km) for a front, and 8-9,000 miles (13-15,000 km) for a rear.
Prices here in Phoenix are about $100US for a Lasertec 100/90-18 front tire, $120US for a Lasertec 120-18 rear tire, mounting and balancing around the $22-$25US, and about $22US each for Metzeler tubes.
You need to use tubes with the rims that the R65 has, some run without them and claim to have no problems, your choice !
I'm sure other members will post their experiences with their choosen tires shortly.
Wonder how long it will take Justin to whack this thread into the off topic section!!!!