DRAFT KENYA STANDARDDKS 76: 2007
New pneumatic tyres for passenger cars —Specification
© KEBS 2007First Edition 2007
TECHNICAL COMMITTEE REPRESENTATION
The following organizations were represented on the Technical Committee:
Automobile Association of Kenya
Applied Management and Technical Solutions Ltd
General Motors East Africa Ltd
Good Year Kenya
Kajulu holdings Ltd
Kingsway Tyres Ltd
Michelin Tyre
Ministry of Roads and Public Works
Nyanza Petroleum Dealers
Pirelli Europe (SA)
Sameer Africa Ltd
Treadsetters Tyres Ltd
Kenya Bureau of Standards — Secretariat
REVISION OF KENYA STANDARDS
In order to keep abreast of progress in industry, Kenya Standards shall be regularly reviewed. Suggestions for improvements to published standards, addressed to the Managing Director, Kenya Bureau of Standards, are welcome.
© Kenya Bureau of Standards, 2007
Copyright: Users are reminded that by virtue of section 6 of the Copyright Act, Cap. 130 of the Laws of Kenya, copyright subsists in all Kenya Standards and except as provided under section 7 of this Act, no Kenya Standard produced by Kenya Bureau of Standards may be reproduced, stored in a retrieval system in any form or transmitted by any means without prior permission in writing from the Managing Director.
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New pneumatic tyres for passenger cars —Specification
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Foreword
This Draft Kenya Standard was prepared by the Technical Committee on Road Safety under the guidance of the Mechanical Engineering Industry Standards Committee, and it is in accordance with the procedures of the Bureau.
Tyres play a vital role in vehicle performance, handling and safety. They carry the full weight of the vehicle, while at the same time providing all of the grip for acceleration, steering and braking while the importance of good tyres is often overlooked or taken for granted. Tyre faults are noted in half of all fatal crashes where vehicle defects are a contributing factor.
Good tyres will holds the vehicle securely on the road, allowing it to stop, start and manoeuvre safely. Worn out, incorrectly inflated or unsuitable tyres may not. The tyres should be in good condition, properly maintained and appropriate for the vehicle.
It is important to have tyres fitted to the car that comply with an approved standard. Tyres should undergo speed, endurance and strength tests to comply with a standard. The tyre retailer should be able to confirm that any tyres he/she sales meet the approved standard.
The purpose of preparing this standard is therefore to assist both the manufacturers and the consumers of tyres.
This standard cancels and replaces KS 76:1978, which has been technically revised.
During the preparation of this standard, reference was made to the following document:
Federal Motor Vehicle Safety Standard No. 109 of USA.
KS 76:1978, Specification for new pneumatic tyres — Passenger cars
E/ECE/324 Rev.1/Add.29/Rev.2 E/ECE/TRANS/505A, Agreement concerning the adoption of uniform technical prescriptions for wheeled vehicles, equipment and parts which can be fitted and/or be used on wheeled vehicles and the conditions for reciprocal recognition of approvals granted on the basis of these prescriptions, Addendum 29: Regulation No. 30.
Acknowledgement is hereby made for the assistance received from these sources.
1
©KEBS 2007— All rights reserved
DKS 76: 2007
New pneumatic tyres p for passengers cars — specification
1Scope
1.1 This draft Kenya standard specifies requirements for new pneumatic tyres designed primarily, but not only, for passenger cars.
1.2 It does not apply to tyres designed for
(a) the equipment for vintage cars
(b) competitions.
2 Definitions
For the purposes of this standard the following definitions shall apply (See figure 1).
2.1
type of pneumatic tyre
a category of pneumatic tyres which do not differ in such essential respects as the manufacturer, tyre-size designation, category of use (ordinary (road-type) or snow tyre or for temporary use, structure (diagonal (bias-ply), bias-belted, radial-ply), speed category symbol, load-capacity index, tyre cross-section,
2.2
snow tyre
a tyre whose tread pattern and whose structure are primarily designed to ensure in mud and fresh or melting snow a performance better than that of an ordinary (road-type) tyre. The tread pattern of a snow tyre generally consists of groove (rib) and/or solid-block elements more widely spaced than on an ordinary (road-type) tyre;
2.3
structure of a pneumatic tyre
the technical characteristics of the tyre's carcass. The following structures are distinguished in particular;
2.3.1
diagonal or bias-ply
a pneumatic-tyre structure in which the ply cords extend to the beads and are laid at alternate angles of substantially less than 90N to the centre line of the tread;
2.3.2
bias-belted
a pneumatic-tyre structure of diagonal (bias-ply) type in which the carcass is restricted by a belt comprising two or more layers of substantially inextensible cord material laid at alternate angles close to those of the carcass
2.3.3.
radial
a pneumatic-tyre structure in which the ply cords extend to the beads and are laid substantially at 90N to the centre line of the tread, the carcass being stabilized by an essentially inextensible circumferential belt
2.3.4
reinforced or extra load
a pneumatic-tyre structure in which the carcass is more resistant than that of the corresponding standard tyre;
Figure 1 — Explanatory figure
2.3.5
temporary use spare tyre
a tyre different from a tyre intended to be fitted to any vehicle for normal driving conditions but intended only for temporary use under restricted driving conditions
2.3.6
T-type temporary use spare tyre
a type of temporary use spare tyre designed for use at inflation pressures higher than those established for standard and reinforced tyres
2.4
bead
the part of a pneumatic tyre which is of such shape and structure as to fit the rim and hold the tyre on it
2.5
cord
the strands forming the fabric of the plies in the pneumatic tyre
2.6
ply
a layer of rubber-coated parallel cords
2.7
carcass
that part of a pneumatic tyre other than the tread and the rubber side walls which, when inflated, bears the load
2.8
tread
that part of a pneumatic tyre which comes into contact with the ground
2.9
side wall
the part of a pneumatic tyre between the tread and the bead
2.10
lower area of tyre
the area included between the point of maximum section width of the tyre and the area designed to be covered by the edge of the rim. However, in case of tyres identified by the “tyre to rim fitment configuration” (see 9.1 (k)) symbol “A”, it means the area of the tyre, which is seating on the rim.
2.11
tread groove
the space between two adjacent ribs or blocks in the tread pattern
2.12
section width
the linear distance between the outsides of the side walls of an inflated pneumatic tyre, excluding elevations due to labelling (marking), decoration or protective bands or ribs
2.13
overall width
the linear distance between the outsides of the side walls of an inflated pneumatic tyre, including labeling (marking), decoration and protective bands or ribs
2.14
section height
a distance equal to half the difference between the outer diameter of the tyre and the nominal rim diameter
2.15
nominal aspect ratio (Ra)
100 times the ratio of the section height, to the section width of the tyre on its theoretical rim
2.16
outer diameter
the overall diameter of an inflated new pneumatic tyre
2.17
tye-size designation
is
2.17.1 a designation showing:
2.17.1.1 the nominal section width. This width shall be expressed in mm, except in the case of the types of tyre for which the size designation is shown in the first column of the tables in annex A of this standard
2.17.1.2 the nominal aspect ratio except in the case of certain types of tyre, for which the size designation is shown in the first column of the tables in annex A to this standard, or depending on the tyre design type, the nominal outer diameter expressed in mm;
2.17.1.3. a conventional number denoting the nominal rim diameter and corresponding to its diameter expressed either by codes (numbers below 100) or in millimetres (numbers above 100);
2.17.1.4 the letter "T" in front of the nominal section width in case of T-type temporary use spare tyres;
2.17.1.5 an indication of the tyre to rim fitment configuration when it differs from the standard configuration.
2.18
nominal rim diameter
the diameter of the rim on which a tyre is designed to be mounted
2.19
rim
the support for a tyre-and-tube assembly, or for a tubeless tyre, on which the tyre beads are seated;
2.19.1
tyre to rim fitment configuration
the type of rim to which the tyre is designed to be fitted. In the case of non-standard rims this will be identified by a symbol applied to the tyre, for example, "CT", "TR", "TD" or "A".
2.20
theoretical rim
the notional rim whose width would be equal to x times the nominal section width of a tyre. The value of x shall be specified by the manufacturer of that tyre
2.21
measuring rim
the rim on which a tyre is required to be fitted for size measurements
2.22
test rim
the rim on which a tyre is required to be fitted for testing
2.23
chunking
the breaking away of pieces of rubber from the tread
2.24
cord separation
the parting of the cords from their rubber coating
2.25.
ply separation
the parting of adjacent plies;
2.26
tread separation
the pulling away of the tread from the carcass
2.27
tread-wear indicators
the projections within the tread grooves designed to give a visual indication of the degree of wear of the tread
2.28
load-capacity index
a number associated to the reference mass a tyre can carry when operated in conformity with requirements governing utilization specified by the manufacturer
2.29
speed category
the maximum speed which the tyre can sustain, expressed by speed category symbol
2.30
tread pattern grooves
2.30.1
principal grooves
the wide grooves positioned in the central zone of the tyre tread, which have the tread-wear indicators (see 2.27) located inside them.
2.30.2
secondary grooves
the supplementary grooves of the tread pattern, which may disappear in the course of the tyre's life.
2.31
maximum load rating
the maximum mass the tyre is rated to carry
2.32
passenger cars
all sedans, coupes, and station wagons manufactured primarily for the purpose of carrying passengers and including those passenger cars pulling recreational or other light trailers
3Speed categories and maximum load rating
3.1 Speed categories
The categories of speed shall be as given in table 1
Table 1 — Speed Categories
Speed – category symbol / Maximum speed (Km/h)J / 100
K / 110
L / 120
M / 130
N / 140
P / 150
Q / 160
R / 170
S / 180
T / 190
U / 200
H / 210
V / 240
W / 270
Y / 300
3.2Maximum load rating
3.2.1 For speeds not exceeding 210 Km/h the maximum load rating shall not exceed the value associated with the load capacity index of the tyre (See table 2)
3.2.2 For other speeds higher than 210 Km/h the maximum load rating shall not exceed the percentage of the value associated with the load capacity index of the tyre given in table 3 with reference to the speed capability of the car to which the tyre is fitted.
Table 2 — Load-capacity indices
Li / Kg / Li / Kg / Li / Kg / Li / Kg0 / 45 / 33 / 115 / 66 / 300 / 99 / 775
1 / 46.2 / 34 / 118 / 67 / 307 / 100 / 800
2 / 47.5 / 35 / 121 / 68 / 315 / 101 / 825
3 / 48.7 / 36 / 125 / 69 / 325 / 102 / 850
4 / 50 / 37 / 128 / 70 / 335 / 103 / 875
5 / 51.5 / 38 / 132 / 71 / 345 / 104 / 900
6 / 53 / 39 / 136 / 72 / 355 / 105 / 925
7 / 54.5 / 40 / 140 / 73 / 365 / 106 / 950
8 / 56 / 41 / 145 / 74 / 375 / 107 / 975
9 / 58 / 42 / 150 / 75 / 387 / 108 / 1 000
10 / 60 / 43 / 155 / 76 / 400 / 109 / 1 030
11 / 61.5 / 44 / 160 / 77 / 412 / 110 / 1 060
12 / 63 / 45 / 165 / 78 / 425 / 111 / 1 090
13 / 65 / 46 / 170 / 79 / 437 / 112 / 1 120
14 / 67 / 47 / 175 / 80 / 450 / 113 / 1 150
15 / 69 / 48 / 180 / 81 / 462 / 114 / 1 180
16 / 71 / 49 / 185 / 82 / 475 / 115 / 1 215
17 / 73 / 50 / 190 / 83 / 487 / 116 / 1 250
18 / 75 / 51 / 195 / 84 / 500 / 117 / 1 285
19 / 77.5 / 52 / 200 / 85 / 515 / 118 / 1 320
20 / 80 / 53 / 206 / 86 / 530 / 119 / 1 360
21 / 82.5 / 54 / 212 / 87 / 545 / 120 / 1 400
22 / 85 / 55 / 218 / 88 / 560 / 121 / 1450
23 / 87.5 / 56 / 224 / 89 / 580 / 122 / 1500
24 / 90 / 57 / 230 / 90 / 600 / 123 / 1550
25 / 92.5 / 58 / 236 / 91 / 615 / 124 / 1600
26 / 95 / 59 / 243 / 92 / 630 / 125 / 1650
27 / 97.5 / 60 / 250 / 93 / 650 / 126 / 1700
28 / 100 / 61 / 257 / 94 / 670 / 127 / 1750
29 / 103 / 62 / 265 / 95 / 690 / 128 / 1800
30 / 106 / 63 / 272 / 96 / 710 / 129 / 1850
31 / 109 / 64 / 280 / 97 / 730 / 130 / 1900
32 / 112 / 65 / 290 / 98 / 750
Table 3 — Maximum load ratings for speeds higher than 210 Km/h
Speed category symbol / Maximum speed Km/h / Maximum load rating (%)V / 215 / 98.5
220 / 97
225 / 95.5
230 / 94
235 / 92.5
240 / 91
W / 240 / 100
250 / 95
260 / 90
270 / 85
Y / 270 / 100
280 / 95
290 / 90
300 / 85
NOTE For intermediate maximum speeds linear interpolations of the maximum load rating are allowed
3.2.3 For speeds lower or equal to 60 km/h the maximum load rating shall not exceed the percentage of mass, associated with the load capacity index of the tyre given in table 4 with reference to the maximum design speed of the vehicle to which the tyre is to be fitted.
3.2.4 For speeds in excess of 300 km/h, the maximum load rating shall not exceed the mass specified by the tyre manufacturer with reference to the speed capacity of the tyre. For intermediate speeds between 300 km/h and the maximum speed permitted by the tyre manufacturer, a linear interpolation of the maximum load rating applies.
Table 4 — Maximum load ratings for speeds less or equal to 60 Km/h
Maximum speed Km/h / Maximum load rating (%)25 / 142
30 / 135
40 / 125
50 / 115
60 / 110
4Dimensions of tyres
4.1 Each manufacturer of tyres shall ensure that a listing of the sizes of tyres and rims that may be used with each tyre that he/she produces is provided. The listing shall be in one of the following forms:
(a) Listed by manufacturer name or brand name in a document furnished to dealers of the manufacturer’s tyres, and to the relevant government authority upon request.
(b) Contained in publications, current at the date of manufacture of the tyre or any later date, of at least one of the following organizations:
The Tire and Rim Association (TRA)
The European Tyre and Rim Technical Organisation (ETRTO)
Japan Automobile Tire Manufacturers’ Association, Inc. (JATMA)
4.2 Information contained in any publication specified in 4.1 (b) which lists general categories of tyres and rims by size designation, type of construction and/or intended use, shall be considered to be manufacturer’s information in accordance with 4.1 for the listed tires and rims, unless the publication itself or specific information provided according to 4.1 (a) indicates otherwise.
NOTE Examples of the tyre size, designation and dimensions are given in Annex A.
4.3 Section width of a tyre
4.3.1 The section width shall be calculated by the following formula:
S = S1 + K (A-A1),
where:
S is the "section width" expressed in mm and measured on the measuring rim;
S1 is the "nominal section width" (in mm) as shown on the side wall of the tyre in the designation of the tyre as prescribed;
A is the width (expressed in mm) of the measuring rim, as shown by the manufacturer.[1]
A1 is the width (expressed in mm) of the theoretical rim.
A1 shall be taken to equal S1 multiplied by the factor x, as specified by the manufacturer, and K shall be taken to equal 0.4.
4.3.2 For the types of tyres for which the designation is given in the first column of the tables in annex A to this standard the section width shall be that given opposite the tyre designation in these tables.
4.3.3 For tyres identified by the "tyre to rim fitment configuration" (see 9.1(l)) symbol "A", K shall be taken equal to 0.6.
4.4 Outer diameter of a tyre
4.4.1 The outer diameter of a tyre shall be calculated by the following formula:
D = d + 2H
where:
D is the outer diameter expressed in mm
d is the conventional number defined in 2.17.1.3, expressed in mm.
H is the nominal section height in mm, equal to:
H = 0.01S1.Ra,
S1 is the nominal section width in mm, and
Ra is the nominal aspect ratio, all as shown on the sidewall of the tyre in the tyre-size designation in conformity with the requirements of 9.4
4.4.2 For the types of tyres for which the designation is given in the first column of the tables of annex A to this Standard the outer diameter shall be that given opposite the "size" designation in these tables.
4.4.3 For tyres identified by the "tyre to rim fitment configuration" (see 9.1 (l)) symbol "A", the outer diameter shall be that specified in the tyre size designation as shown on the sidewall of the tyre.
5 Test requirements
5.1Physical dimensions
The dimensions of pneumatic tyres shall be measured by the procedure described in annex B to this standard
5.1.1 Tyre section-width specifications
5.1.1.1 The overall width of a tyre may be less than the section width determined in accordance with 4.3.
5.1.1.2 It may exceed that value by the following percentages:
a) in diagonal (bias-ply) tyres: 6%;
b) in radial-ply tyres: 4%;
c) in addition, if the tyre has special protective ribs (or bands), the figure as increased by the above tolerance may be exceeded by 8 mm.
5.1.1.3 For tyres identified by the "tyre to rim fitment configuration" (see 9.1(l) symbol "A", the overall width of the tyre, in the lower area of the tyre, equals the nominal width of the rim on which the tyre is mounted, as shown by the manufacturer in the descriptive note, increased by 20 mm.
5.1.2 Tyre outer-diameter specifications
The outer-diameter of a tyre shall not be outside the values Dmin and Dmax obtained from the following formulae:
Dmin = d + (2H . a)
Dmax = d + (2H . b)
where:
for sizes listed in annex A, and for tyres identified by the "tyre to rim fitment configuration" (see 9.1(l)) symbol "A", the nominal section height H is equal to:
H = 0.5 (D-d), for references see 4.4.
Coefficients "a" and "b" are respectively:
Coefficient "a" = 0.97
Coefficient "b" (road type) for ordinary tyres, Radial = 1.04, Diagonal and Bias Belted = 1.08
For other sizes, not listed in annex A, "H" and "d" are as defined in 4.4.1,
For snow tyres the overall diameter (Dmax) established in conformity with the above may be exceeded by 1%.
5.2 Tyre strength and endurance tests
5.2.1 Tyre strength test
When tested in accordance with annex C each tyre shall meet the requirements for minimum breaking energy specified in tables 4, 5 and 6.
Table 4 — For Bias ply tyres with designated section width of 152 mm and above
Code material
/ psi / kPa32 / 36 / 40 / 240 / 280 / 300 / 340
Rayon (joules) / 186 / 291 / 373 / 186 / 373 / 186 / 373
Nylon or polyester (joules) / 294 / 441 / 588 / 294 / 588 / 294 / 588
Table 5 — For Bias ply tyres with designated section width below 152 mm
Code material
/ psi / kPa32 / 36 / 40 / 240 / 280 / 300 / 340
Rayon (joules) / 113 / 212 / 282 / 113 / 282 / 113 / 282
Nylon or polyester (joules) / 220 / 330 / 441 / 220 / 441 / 220 / 441
Table 6 — For radial ply tyres
Size designation / Maximum permissible inflation pressureTyres other than CT tyres
/CT tyres
psi / kPa / kPa32 / 36 / 40 / 240 / 280 / 300 / 340 / 350 / 290 / 330 / 350 / 390
Below 160 mm (joules) / 220 / 330 / 441 / 220 / 441 / 220 / 441 / 220 / 220 / 441 / 220 / 441
160 mm or above (joules) / 294 / 441 / 588 / 294 / 588 / 294 / 588 / 294 / 294 / 588 / 294 / 588
5.2.2 Tyre Endurance test