i used kenda 671's on the rt125 and they seem to do ok but i do not go very fast ps big singles eat up 3 things
1 roads with sharp cornors
2 GAS
3 rear tires in short order
my saxon tour 500cc has about 3000 miles on rear and next summer
at about 5,500 it will look like a Oscar Mayer Bologna skin
EVERY TIME IT THUMPS IT RIPS A BIT MORE RUBBER OFF THE TIRE
http://www.kendausa.com/motorcycle/street.html
tell your shop parts unlimited has them
check and print the link
ar dave
note i use stock size tires unless they are not sold in my area like the saxon tour needs 110/80-16 not sold in usa so i did 120/80-16 from rear of buell blast jacks up the rear making a fast steering bike even faster