Technical Data

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Technical Data
Aspect ratio is the relationship between the section height and the section width of the tire. This numerical expression is sometimes referred to as series; i.e., 50 Series.

Section Height /Section Width=Aspect Ratio

Example: 235/60R15 91V

Section Width. 235/25.4" = 9.25"

Overall Diameter. 26.10"

26.10 - 15.00" = 11.10"

11.10"/2 = 5.55"

Therefore.

5.55"/9.25= 60%

Tire Dimension Formulas

Section Width

235/25.4 = 9.25"

In this formula 25.4 is a constant number(the numbers of millimeters in one inch), divide the section width in millimeters by 25.4 to determine the section width in inches.

Section Height

Section Width x Aspect Ratio = Section Height

Overall Diameter

(Section Height x 2) + (Wheel Diameter) = Overall Diameter

(5.55" x 2) + 15.00"= 26.10"

Disclaimer:

These possible conversions do not imply interchange-ability. Body and chassis clearance under conditions should be carefully checked for every car model and every time a replacement is made. The overall diameter of the Pirelli replacement tire is included between -3% to +2% of the related O.E.M. tire size. The maximum load index as speed rating of the replacement tire should be equivalent to or higher then the original O.E.M. tire fitment.

Technical data was provided by euro-tire and Pirelli.

Possible Tire Conversions

Rim Size

OE Size

1st Opt.

Plus 1

Plus 2

Plus 3

13

175/70 R13

205/60 R13

185/60 R14

185/55 R15

195/45 R16

185/70 R13

205/60 R13

195/60 R14

205/50 R15

205/45 R16

14

185/70 R14

195/65 R14

195/60 R15

205/50 R16

215/40 R17

195/70 R14

215/60 R14

195/65 R15

205/50 R16

215/45 R17

Disclaimer:

These possible conversions do not imply interchangeability. Body and chassis clearance under conditions should be carefully checked for every car model and every time a replacement is made. The overall diameter of the Pirelli replacement tire is included between -3% to +2% of the related O.E.M. tire size. The maximum load index as speed rating of the replacement tire should be equivalent to or higher then the original O.E.M. tire fitment.

Speed Indicator

How Fast Are the Tires Good For?

Speed

Maximum

Index

Speed
(in M.P.H.)

K

68

L

74

M

81

N

87

P

93

Q

99

S

112

T

118

H

130

V

149

Z

Over 150

Load Index

What That Means in Carrying Capacity

Load

Weight/

Load

Weight/

Load

Weight/

Index

Tire (#)

Index

Tire (#)

Index

Tire (#)

60

551

80

992

100

1764

61

567

81

1019

101

1819

62

584

82

1047

102

1874

63

600

83

1074

103

1929

64

617

84

1102

104

1984

65

639

85

1135

105

2039

66

661

86

1168

106

2094

67

677

87

1202

107

2138

68

694

88

1235

108

2205

69

716

89

1279

109

2271

70

739

90

1323

110

2337

71

761

91

1356

111

2403

72

783

92

1389

112

2469

73

805

93

1433

113

2535

74

827

94

1477

114

2601

75

853

95

1521

115

2679

76

882

96

1565

116

2756

77

908

97

1609

117

2833

78

937

98

1653

118

2910

79

963

99

1709

119

2998

Uniform Tire Quality Grade Labeling

Toward that objective, we present here an "Official" document that "Describes" the system. We're not sure that this will increase your knowledge of tires, but at least  it explains what some of the markings on them are supposed to convey! Without further ado:

The Uniform Tire Quality Grading System (UTQGS) is a tire information system that
provides buyers with information on three categories:
Each tire manufacturer performs its own tests in these areas, following government prescribed test procedures. Each manufacturer then assigns grades that are branded on the tire. This is known as the Uniform Tire Quality Grade Labeling (UTQGL).


Treadwear

Treadwear grades typically range from 60 to over 500, in twenty point increments. It's important to remember that the actual life of any tire is determined by the road surface quality, driving habits, inflation, wheel alignment and the rotation it experiences. To receive a treadwear grade, a tire is tested under controlled conditions on a government prescribed test course which does not necessarily simulate the actual application for which a given tire is designed to perform. As a result of these test parameters, there is no reliable way to assign miles of wear to treadwear grade points.

Treadwear ratings are determined on a 400 mile government test course covering specified sections of public roads near San Angelo, Texas. A group of not more than four test vehicles travels the course in a convoy so that all tires experience the same conditions. Tread groove depths of the tires being tested are measured after each 800 miles. The same procedure is followed for a set of control or "course monitoring tires." Upon completion of the 7,200 mile test, the rating results of both tests are compared, and the tires being tested are assigned a treadwear rating by the tire manufacturer.

The best way to use treadwear ratings when buying tires is to compare one rating to another. For instance, a tire with a treadwear grade of 400 might be expected to last twice as long as a tire that has a grade of 200.

Traction
 

Traction grades indicate the measurement of a tire's ability to stop a car in straight-ahead motion on a wet test surface pavement. It does not measure straight-ahead acceleration. It's important to remember that traction rating tests are performed only for straight ahead sliding on concrete and asphalt surfaces that have a specified degree of wetting which simulates most road surfaces in a rainstorm. The ratings that result from these tests may not apply to cornering traction or peak values of straight-ahead braking force like those experienced in non-skid braking tests. Traction grades range from A to C, with A being the highest attainable grade.
 

Traction ratings are established on government maintained skid pads. Twenty measurements are taken with an industry standard control tire on an asphalt surface and averaged. The same number of measurements are made on a concrete surface. Corresponding measurements are then made on the tires being tested. Once the results of the tests are compared, traction ratings based on government prescribed coefficient levels are assigned to the tires that were tested.

Temperature

Temperature grades also range from A to C, with A being the highest. Temperature grades represent a properly maintained tire's ability to dissipate heat under controlled indoor test wheel conditions.

Temperature ratings are determined by running tires on an indoor road wheel test under specified conditions. Successive 30-minute runs are made in 5 mph increments starting at 75 mph and continuing until the tire fails. A tire is graded "C" if it meets the minimum performance required by DOT. Grades of "B" and "A" represent higher levels of performance than the minimum required by DOT.

Proper Procedures

Only specially trained persons should mount tires. Improper tire mounting and inflation procedures may cause tire beads to break with explosive force during installation of the tire on the rim causing serious personal injury, death and property damage. Follow the Rubber Manufacturer's Association (RMA) installation and safety procedures for mounting and inflating tires. Tire and rim diameter must match in size. Do not take another person's word for it; check the tire size and the wheel size for proper match. Never inflate tires to fit a wheel mounted by someone else without first checking both wheel and tire size. Clean the rim. Lubricate the rim and beads. If the tire does not seat on the rim at 40 psi, disassemble, recheck sizes, and lubricate before airing up again. Use remote control inflation equipment and inflation cage or some other approved restraining device.