Ply
Rating vs. Load Range
Ply ratings & load ranges identify load & inflation limits of a given
tire size when used in a specific type of service.
- Ply ratings: An older method of rating load capacity,
these are listed as 4-ply, 6-ply, 8-ply, etc.
- Load ratings: The current method of rating a tire's
load-carrying capacity is denoted by letters (B, C, D, E, etc.).
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Uniform Tire Quality Grade (UTQG) Labeling
Required by the government, the UTQG provides comparative manufacturer
information. Tires are subjected to a series of government-mandated tests
that measure performance in treadwear, traction & temperature resistance.
All testing is done by the tire manufacturer. |
Treadwear
Treadwear is a measurement of tread durability. Tested against an industry
standard, the assigned numerical grade indicates how well the tread lasts
compared with a reference standard of 100. A treadwear rating 200 means the
tread wears twice as well as the standard. Actual wear depends on the
conditions under which the tire is used. Driving habits, service practices,
differences in road surface & varying climates all affect treadwear. |
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Traction
Traction is a measurement of a tire's ability to stop on wet test surfaces
of asphalt & concrete under controlled conditions. Traction grades are
assigned by the UTQG system & branded on the sidewall. Traction grade is
determined only for straight-ahead, wet braking on concrete & asphalt. It
doesn't include cornering, which may also be an important customer
performance need.
Traction Grade A: The tire performed well on both surfaces.
Traction Grade B: The tire performed well on at least one of the surfaces.
Traction Grade C: The tire performed poorly on one or both of the surfaces.
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Temperature Resistance
The UTQG also provides a measure of resistance to heat generation under
normal operating conditions. The test is conducted under predetermined
standards for inflation & loading. Excessive speed, underinflation &
overloading can all cause adverse heat build-up. Sustained high temperatures
can reduce tire durability. Resistance grades are branded on the sidewall.
Resistance Grade A: The maximum performance level indicating the tire
withstood a half-hour run at 115 mph without failing.
Resistance Grade B: The tire passed 100 mph but not 115 mph.
Resistance Grade C: The minimum performance level indicating that the tire
failed to complete a half-hour at 100 mph. |
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Department of Transportation (DOT)
Certification
"DOT" is branded on the tire's sidewall indicating the tire is certified by
the Department of Transportation. Following the DOT branding is a serial
number designating the tire manufacturer, manufacturing plant, tire size &
date of manufacture. Federal law requires that tire dealers record the DOT
identification numbers along with the tire buyer's name & address. |
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Additional Tire Labeling Conventions
Mud & Snow Labeling
If a tire is rated for safe performance in mud & snow, it will be noted on
the sidewall of the tire with either M/S, M+S or M&S. A tire is certified
under the definitions set forth by the Rubber Manufacturers Association (RMA). |
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Tire Construction Labeling
Tread ply & sidewall ply information, including tire ply composition &
materials used, must also be identified. An example would be: Tread: 2 Plies
Rayon + 4 Plies Fiberglass Sidewall: 2 Plies Rayon |
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