Yamaha YFZ 2018 Owner's Manual page 142

Secondary reduction ratio:
2.714 (38/14)
Final drive:
Chain
Clutch type:
Wet, multiple-disc
Transmission type:
5-speed
Gear ratio:
1st:
2.500 (35/14)
2nd:
2.000 (30/15)
3rd:
1.632 (31/19)
4th:
1.333 (28/21)
5th:
1.095 (23/21)
Front tire:
Size:
AT21 x 7R10
Manufacturer/model:
10
MAXXIS/MS21
Rear tire:
Size:
AT20 x 10R9
Manufacturer/model:
MAXXIS/MS22
Tire air pressure (measured on cold tires):
Vehicle load:
0.0–100.0 kg (0–220 lb)
Recommended:
Front:
35.0 kPa (0.350 kgf/cm², 5.0 psi)
Rear:
35.0 kPa (0.350 kgf/cm², 5.0 psi)
Minimum:
Front:
32.0 kPa (0.320 kgf/cm², 4.6 psi)
Rear:
32.0 kPa (0.320 kgf/cm², 4.6 psi)
Front wheel:
Rim size:
10 X 5.5AT
Rear wheel:
Rim size:
9 X 8.0AT
Front brake:
Type:
Hydraulic disc brake
Rear brake:
Type:
Hydraulic disc brake
Brake fluid:
Specified brake fluid:
DOT 4
Front suspension:
Type:
Double wishbone
Spring:
Coil spring
10-3