These are the sizes for the tires and tubes I bought. The front is a tad bit bigger, but you won't even notice after you ride for 50 miles. As well, the larger front tire doesn't cause any issues and in my opinion looks better since it sits up more in the rim.
got them at:
http://www.americanmototire.com/(thanx SSJONES)
METZELER ME880 110/90HB-18 FRONT
METZELER ME880 170/80HB-15 REAR
BRIDGESTONE TUBE (ULTRA HEAVY DUTY) 110/100-18
BRIDGESTONE TUBE 170/80-15 (90 DEGREE STEM)
