Looking for replacement tires for my venerable 1985 Yamaha FJ-600. Stock tire sizes were 110/90-18 rear and 90/90-18 front. These don't exactly seem to be common sizes anymore and I was wondering what other sizes and models would be close enough. The wheels are cast aluminum MT 2.50 X 18 rear and MT 2.15 X 18 front. Thanks in advance. Mike