OHIOSTEEL Utility Trailer, Owner'S Manual

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axle its share of the curb weight, accessory weight, and 
normal occupant weight (distributed in accordance with 
Table I of CRF 49 571.110) and dividing by 2.

Weather side:

 The surface area of the rim not covered 

by the infl ated tire.

Wheel center member:

 In the case of a non-

pneumatic tire assembly incorporating a wheel, a 
mechanical device which attaches, either integrally 
or separably, to the non-pneumatic rim and provides 
the connection between the nonpneumatic rim and 
the vehicle; or, in the case of a non-pneumatic tire 
assembly not incorporating a wheel, a mechanical 
device which attaches, either integrally or separably, 
to the non-pneumatic tire and provides the connection 
between tire and the vehicle.

Wheel-holding fi xture:

 The fi xture used to hold the 

wheel and tire assembly securely during testing.

3.5  Tire Safety - Everything Rides On It

The National Traffi c Safety Administration (NHTSA) 
has published a brochure (DOT HS 809 361) that 
discusses all aspects of Tire Safety, as required by 
CFR 575.6. This brochure is reproduced in part below. 
It can be obtained and downloaded from NHTSA, free 
of charge, from the following web site:

http://www.nhtsa.dot.gov/cars/rules/TireSafety/
ridesonit/tires_index.html

Studies of tire safety show that maintaining proper 
tire pressure, observing tire and vehicle load limits 
(not carrying more weight in your vehicle than your 
tires or vehicle can safely handle), avoiding road 
hazards, and inspecting tires for cuts, slashes, and 
other irregularities are the most important things you 
can do to avoid tire failure, such as tread separation or 
blowout and fl at tires. These actions, along with other 
care and maintenance activities, can also:

• 

Improve vehicle handling

• 

Help protect you and others from avoidable 
breakdowns and accidents

• 

Improve fuel economy

• 

Increase the life of your tires.

This booklet presents a comprehensive overview of tire 
safety, including information on the following topics:

• 

Basic tire maintenance

• 

Uniform Tire Quality Grading System

Rim diameter: 

This means the nominal diameter of 

the bead seat.

Rim size designation:

 This means the rim diameter 

and width.

Rim type designation:

 This means the industry of 

manufacturer’s designation for a rim by style or code. 

Rim width:

 This means the nominal distance between 

rim fl anges.

Section width:

 The linear distance between the 

exteriors of the sidewalls of an infl ated tire, excluding 
elevations due to labeling, decoration, or protective 
bands.

Sidewal

l: That portion of a tire between the tread and 

bead. 

Sidewall separation:

 The parting of the rubber 

compound from the cord material in the sidewall.

Special Trailer (ST) tire: 

The “ST” is an indication the 

tire is for trailer use only.

Test rim: 

The rim on which a tire is fi tted for testing, 

and may be any rim listed as appropriate for use with 
that tire.

Tread:

 That portion of a tire that comes into contact 

with the road.

Tread rib:

 A tread section running circumferentially 

around a tire.

Tread separation:

 Pulling away of the tread from the 

tire carcass.

Treadwear indicators (TWI):

 The projections within 

the principal grooves designed to give a visual 
indication of the degrees of wear of the tread.

Vehicle capacity weight: 

The rated cargo and 

luggage load plus 68 kilograms (150 lbs.) times the 
vehicle’s designated seating capacity.

Vehicle maximum load on the tire:

 The load on an 

individual tire that is determined by distributing to each 
axle its share of the maximum loaded vehicle weight 
and dividing by two.

Vehicle normal load on the tire:

 The load on an 

individual tire that is determined by distributing to each 

Tire Safety