Honda CRF250F Owner's Manual Installation And Operation page 227

CHASSIS AND SUSPENSION
Caster
Trail
Tyre size, front
Tyre size, rear
Tyre type
POWER TRANSMISSION
Primary reduction
Gear ratio, 1st
2nd
3rd
4th
5th
Final reduction
102
26°5'
102 mm (4.0 in)
80/100-21 51R NHS
100/100-18 59R NHS
bias-ply, tube
2.863
2.846
1.900
1.400
1.083
0.896
3.846