rear stock is an ungodly odd 18x4... comes with a 140/70... 150/60 fits.
It was fine back in 89 when introduced... nothing turned quite like it... but by mid 90's there was a reason the YZF were out.

I think it made 70-80hp... made more torque down low than my old zx6 due to their longer stroke.

Yamaha should of put an luminum frame and the yzf suspension on the FZR's... would have been the lightest and nimbles bikes on the market... instead they came with the YZF that turned out to be heavier at 1st...