2009 YAMAHA GRIZZLY 450 tire size

1-3
1 steady speed when climbing a hill. If you stall or
roll backwards, follow the special procedure for
braking described in this manual. Dismount on
the uphill side or to a side if pointed straight up-
hill. Turn the ATV around and remount, following
the procedure described in this manual.

Always check for obstacles before operating in a
new area.
Never attempt to operate over large obstacles,
such as large rocks or fallen trees. Always follow
proper procedures when operating over obsta-
cles as described in this manual.
Always be careful when skidding or sliding.
Learn to safely control skidding or sliding by
practicing at low speeds and on level, smooth
terrain. On extremely slippery surfaces, such as
ice, go slowly and be very cautious in order to re-
duce the chance of skidding or sliding out of con-
trol.
Never operate an ATV in fast flowing water or in
water deeper than that recommended in this
manual. Remember that wet brakes may have
reduced stopping ability. Test your brakes after
leaving water. If necessary, apply them several
times to let friction dry out the linings.

Always be sure there are no obstacles or people
behind you when you operate in reverse. When
it is safe to proceed in reverse, go slowly.
Always use the size and type of tires specified in
this manual.
Always maintain proper tire pressure as de-
scribed in this manual.
Never modify an ATV through improper installa-
tion or use of accessories.
Never exceed the stated load capacity for an
ATV. Cargo should be properly distributed and
securely attached. Reduce speed and follow in-
structions in this manual for carrying cargo or
pulling a trailer. Allow greater distance for brak-
ing.
WARNING
EWB00061
Always turn off the engine when refueling.
Do not refuel right after the engine has been
running and is still very hot.
Do not spill gasoline on the engine or ex-
haust pipe/muffler when refueling. Never re-
fuel while smoking, or in the vicinity of
sparks, open flames, or other sources of ig-
U37S60E0.book Page 3 Thursday, June 5, 2008 6:51 PM

5-5
5
EBU19812Tires
WARNING
EWB00592Use of improper tires on this ATV, or operation
of this ATV with improper or uneven tire pres-
sure, may cause loss of control, increasing
your risk of accident.
Pay attention to the following.
The tires listed below have been approved
by Yamaha Motor Manufacturing Corpora-
tion of America for this model. Other tire
combinations are not recommended.
Front:
Manufacturer/model:
CHENG SHIN/C-828 (AUS)(NZL)
MAXXIS/M979 (EUR)
Size:
AT25 x 8-12
Type:
Tubeless
Rear:
Manufacturer/model:
CHENG SHIN/C-828 (AUS)(NZL)
MAXXIS/M980 (EUR)
Size:
AT25 x 10-12Type:
Tubeless

The tires should be set to the recommended
pressure:
Recommended tire pressure:
Front:
25.0 kPa (0.250 kgf/cm², 3.6 psi)
Rear:
25.0 kPa (0.250 kgf/cm², 3.6 psi)
Check and adjust tire pressures when the
tires are cold.
Tire pressures must be equal on both
sides.
Tire pressure below the minimum speci-
fied could cause the tire to dislodge from
the rim under severe riding conditions.
Minimum tire pressure:
Front:
22.0 kPa (0.220 kgf/cm², 3.2 psi)
Rear:
22.0 kPa (0.220 kgf/cm², 3.2 psi)
Use no more than the following pressures
when seating the tire beads.
Maximum tire seating pressure:
Front:
250 kPa (2.5 kgf/cm², 36 psi)
U37S60E0.book Page 5 Thursday, June 5, 2008 6:51 PM

7-6
7in the Owner’s Manual. Failure to inspect the
ATV before operating or failure to properly
maintain the ATV increases the possibility of
an accident or equipment damage.
WARNING
EWB01440Always use the size and type tires specified in
the Owner’s Manual for this ATV on page 5-5.
Always maintain proper tire pressure as de-
scribed in the Owner’s Manual on page 5-6.
Use of improper tires on this ATV, or operation
of this ATV with improper or uneven tire pres-
sure, may cause loss of control, increasingyour risk of an accident.
Do not operate at speeds too fast for your skills
or the conditions.
WARNING
EWB01450Always go at a speed that is proper for the ter-
rain, visibility and operating conditions, and
your experience. Operating this ATV at speeds
too fast for your skills or the conditions in-
creases your chances of losing control of theATV, which can result in an accident.Speed limiter
For riders less experienced with this model, the
throttle lever housing is equipped with a speed lim-
iter. The speed limiter keeps the throttle from fully
opening, even when the throttle lever is pushed to
the maximum. Turning in the adjusting screw limits
the maximum engine power available and de-
creases the maximum speed of the ATV. Turning
in the adjusting screw decreases top speed, and
turning it out increases top speed. (See page
4-12.)
1. Adjusting screw
U37S60E0.book Page 6 Thursday, June 5, 2008 6:51 PM

10-3
10
Type × quantity:
BSR33 x 1Spark plug (s):Manufacturer/model:
NGK/DR8EA
Spark plug gap:
0.6–0.7 mm (0.024–0.028 in)Clutch:Clutch type:
Wet, centrifugal automaticTransmission:Primary reduction system:
V-belt
Secondary reduction system:
Shaft drive
Secondary reduction ratio:
39/24 × 24/18 × 33/9 (7.944)
Transmission type:
V-belt automatic
Operation:
Left hand operation
Reverse gear:
29/17 (1.706)
Low range:
45/16 (2.813)
High range:
38/23 (1.652)Chassis:Frame type:
Steel tube frameCaster angle:
2.5 °
Trail:
8.5 mm (0.33 in)
Front tire:Type:
Tubeless
Size:
AT25 x 8-12
Manufacturer/model:
CHENG SHIN/C-828 (AUS)(NZL)
MAXXIS/M979 (EUR)Rear tire:Type:
Tubeless
Size:
AT25 x 10-12
Manufacturer/model:
CHENG SHIN/C-828 (AUS)(NZL)
MAXXIS/M980 (EUR)Loading:Maximum loading limit:
210.0 kg (463 lb)
(Total weight of rider, cargo, accessories, and tongue)Tire air pressure (measured on cold tires):Recommended:
Front:
25.0 kPa (0.250 kgf/cm², 3.6 psi)
Rear:
25.0 kPa (0.250 kgf/cm², 3.6 psi)
U37S60E0.book Page 3 Thursday, June 5, 2008 6:51 PM