2008 Toyota 4Runner Owners Manual - Page 404

07 12.25 Tire related term Meaning a tire that attains a traction index equal to or greater than 110, compared to the ASTM E −1136 Standard Reference Test Tire, when using the snow traction test as described in ASTM F −1805 −00, Standard Test Method for Single Wheel Driving Traction in a Straight Line on Snow −and Ice −Covered Surfaces, and which is marked with an Alpine Symbol ( ) on at least one sidewall the rim on which a tire is fitted for testing, and may be any rim listed as appropriate for use with that tire that portion of a tire that comes into contact with the road a tread section running circumferentially around a tire pulling away of the tread from the tire carcass the projections within the principal grooves designed to give a visual indication of the degrees of wear of the tread the fixture used to hold the wheel and tire assembly securely during testing Snow tire Test rim Tread Tread rib Tread separation Treadwear indicators(TWI) Wheel −holding fixture 362