Check if the treadwear indicators are showing on the tires. Also check the tires for uneven wear, such as excessive wear on one side of the tread. Check the spare tire condition and pressure if not rotated.

The location of treadwear indicators is shown by a “TWI” or “
” marks,
etc., molded into the sidewall of each tire.
Replace the tires if the treadwear indicators are showing on a tire.
Tires
Tire rotationInspection
1. INSPECT SHOCK ABSORBER ASSEMBLY REAR LH
(a) Push down and pull up the shock absorber rod, and
check that there is no unusual resistance or unusual
operation sound.
If there is any malfunction, replace the shock
absorber with a new one.
NOTICE:
When disposing of the shock absorber, se ...
Precaution
1. HANDLING PRECAUTIONS ON STEERING SYSTEM
(a) Be careful to replace the parts properly because
they could affect the performance of the steering
system and result in a driving hazard.
2. HANDLING PRECAUTIONS ON SRS AIRBAG
SYSTEM
(a) The SIENNA is equipped with SRS (Supplemental
Restraint Sys ...
Installation
1. INSTALL HIGH MOUNTED STOP LIGHT ASSEMBLY
2. INSTALL REAR SPOILER
Install the rear spoiler with the 3 nuts and 2 clips.
Connect the center stop light connector.
3. INSTALL BACK DOOR CENTER GARNISH
Engage the 5 clips to install the back door center
garnish.
...