TZS 618: 1999                                                                                                       
                                                                                                     ICS 83.160.10  
 
 
© TBS 2017                                                                                                 Second Edition2017  
 DRAFT TANZANIA STANDARD  
 
 
Pneumatic tyres for passenger cars – Specification             
(Rev TZS 618:1999)  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
TANZANIA BUREAU OF  STANDARDS  
 TZS 618 : 1999  
 
ii                                                                                              ©TBS 1999 – All rights reserved   
 
This Tanzania Standard was published under the authority of the Executive Counci l of 
Tanzania Bureau of Standards on 1999 – 12 – 20. 
 
The Tanzania Bureau of Standards (TBS) is the statutory national standards body for 
Tanzania established under the Standard Act No. 3 of 1975 amended by Act No.  1 of 1977.  
 
The Chemical Divisional Stan dards Committee under whose supervision this Tanzania 
Standard was prepared, consists of representatives from the following organizations:  
 
University of Dar es Salaam  (Department of Chemistry)  
Muhimbili University College of Heath Sciences (Faculty of Ph armacy)  
Tanzania Oxygen Ltd.  
*General Tyre East Africa Ltd.  
*Bora Industries Ltd  
Tanzania Italian Petroleum Refining Company Ltd  
Ministry of Commerce and Industries  
Mansoor Daya Chemicals  
Tanganyika  Tegry (Plastics)  Company Limited  
Tanzania Industria l and Scientific Consultant Organization  
 Medicare Company Limited  
 *Government Chemical Laboratory  
  
 
The organizations marked with an asterisk (*) in the above list, together with the following 
were directly represented on the Technical Committee entru sted in the preparation of this 
Tanzania Standard:  
 
 
University of Dar  es  Salaam (Faculty of Mechanical Engineering)  
Tanzania Industrial Research Development Organization (TIRDO)  
Small Scale Industries Development Organization  (SIDO)  
National Bicycle C ompany (NABICO)   
 
 
Tanzania Bureau of Standards  
P. O. Box 9524  
Dar es Salaam  
Phone:  2450206 / 2450298 / 2450949  
Fax:  2450959  
E-mail: info@tbstz.org  
 
 
ISBN 9976  64  481  7                                                         
  
 
   
TANZANIA STANDARD                                         TZS 618: 1999  
                                                              
©TBS 1999 – All rights reserved                                                                                                1  
Pneumatic tyres for passenger cars – Specification  
 
 
0  Foreword  
 
 
This Tanzania Standard has been prepared in order to give the necessary specifications and 
requirements for test of pneumatic tyres.  It provides important information to be observed for 
improvement of motor v ehicle safety in the country.  
 
In reporting the results of a test made in accordance with this Tanzania Standard, if the final 
value observed or calculated is to be rounded off unless otherwise explained, it shall be done 
in accordance with TZS 4:1979 (see  clause 3).  
 
In the preparation of this Tanzania Standard, assistance was derived from:  
 
a) BS AU 50 (Part 1): subsection 1 1b: 1996: ISO 4000 –1995 Tyres and wheels – car 
tyres – Specification for metric series tyres; published by the British Standards 
Institution.  
 
b) IS 10914 (Part 30: 1991 Automotive vehicles – pneumatic tyres  – Diagonal ply – 
specification - passenger car tyres; published by the Bureau of Indian Standards.  
 
c) Some company standards form our local industries.  
 
 
1 Scope      
 
This Tanzania Standa rd specifies tyre dimensions designation and marking requirements; 
and load ratings.  It also gives laboratory test requirements for bead unseating resistance, 
strength, endurance and high - speed performance for tyres primarily intended for passengers.  
 
2 Application  
 
This Tanzania Standard applies to new pneumatic tyres for use on passenger cars.  It does 
not apply to any tyre which has been reconditioned; or to any tyre which has been altered so 
as to render impossible its use, or its repair for use, as   motor vehicle equipment.  
 
 
3 References  
 
This Tanzania Standard makes reference to the following Tanzania standards:  
 
a) TZS 4: 1979, Rounding off numerical values  
b) TZS 427: 1989 , Tyre reconditioning – Specification   
 
 
4 Terminology   
 
 
For the purpose of th is Tanzania Standard, the definitions given in TZS 427: 1989 (see clause 
3) and the following, shall apply:  
 
4.1 carcass : The tyres structure, except tread and sidewall rubber.   
2                                                                                              ©TBS 1999 – All rights reserved   
4.2 chunking:  The breaking away of pieces of the tread or sidewall.  
 
 
4.3 cracking:  The parting with the tread, sidewall or innerliner of the tyre extending to cord 
material.  
 
4.4   CT:  A pneumatic tyre with inverted flange tyre and rim system in which the rim is 
designed with rim flanges pointed radically inward and the tyre is de signed to fit on the 
underside of the rim in a manner that enclosed the rim flanges inside the air cavity of the tyre.  
 
4.5 groove:  the space between two adjacent tread ribs.  
 
4.6 innerliner:   the layer(s) forming the inside surface of a tubeless tyre tha t contains the 
inflating medium within the tyre.  
   
4.7 innerliner separation:  the parting of the innerliner form the cord material in the carcass.  
 
4.8 load rating:   (index) the maximum load of a tyre rated to carry for a given inflation 
pressure.  
 
4.9 pl y rating:  An index of casing strength, and does not necessarily represent the number of 
cord plies in a tyre.  With modern cords such as rayon, nylon and even steel cords, which are 
much stronger than the cotton or canvas cords which were originally used; the ply rating 
indicated on the tyre in usually higher than the actual number of plies used in tyre 
construction.  
 
4.10 maximum permissible inflation pressure:  The maximum cold inflation pressure to 
which a tyre may be inflated.  It does not include any pr essure build -up due to tyre usage.  
 
4.11 maximum load rating:  The load rating at the maximum inflation pressure for that tyre.  
 
4.12 open splice:  Any parting at any junction of the tread, sidewall, or innerliner that extends 
to cord material.  
 
4.13 overall  width:  The linear distance between the exteriors of the sidewalls of an inflated 
tyre, including elevations due to labeling, decorations or protective bands or ribs.  
 
4.14 rim:  The metal support for a tyre or a tyre and tube assembly upon which the tyre b eads 
are seated.  
 
4.15 test rim:  With reference to a tyre to be tested, any rim that is listed as appropriate for 
use with that tyre in any standard tyre -and-rim matching information.  
 
4.16   tread rib:  A tread section running circumferentially around a ty re. 
 
5 Tyre designation  
 
5.1 Size and construction  
 
 Each tyre shall have one size designation in metric, except that equivalent inch size 
designations may be used.    
 
 
 
 
 
 
 
The characteristics shall be indicated as follows.   
©TBS 1999 – All rights reserved                                                                                              3  
 
 
 
 
  Nominal  /  Nominal   Tyre    Nominal  
  Section  /   aspect    construction   rimdiameter      
              Width   /   ratio     code    code  
 
 
5.1.1 Nominal section width   
 
The nominal section width of the tyre shall be indicated in millimetres, ending either in 0 or 5, 
so th at in any one series of tyres with the same nominal aspect ratio, the values shall all end 
with 0 or end with 5.   An equivalent marking in inch is permitted.  
 
For sizes mounted on 5° tapered (code -designated) rims, the nominal section width shall end 
with 5. 
 
 5.1.2  Nominal aspect ratio  
 
 The nominal aspect ratio shall be expressed as a percentage and shall be a multiple  of 5.  
 
 5.1.3    Type construction code  
 
The tyre construction code shall be as follows:  
 
B for bias -belted construction  
D / for diagonal  construction  
R for radial ply construction  
 
 
NOTE  - Radial tyre designated for some existing vehicle with maximum speed capabilities in 
excess of 210 km/ h or 240  km/h may be designated and marked differently.  See Annex C.  
 
In the case of tyres design ed for vehicles   having a maximum speed capability in excess of 
240 km/h, the code letters “ ZR” may be indicated in the dimensional and constructional 
characteristics for radial ply tryes in pace of the tyre construction code “ R”. 
 
For speeds in excess of  300km/h, the tyres shall be marked with the code -letters “ ZR”. 
 
5.1.4  Nominal rim diameter code  
 
For tyres mounted on 5° tapered (code - designated) rims, the code shall be as given in  
Table 1.  
 
For tyres requiring new concept rims, for safety reasons esp ecially concerning mounting, the 
code number shall be equal to the nominal rim diameter ( Dr) expressed as a whole number of 
millimetres.  
 
 
 
 
 
 
 
 
 
 
  
4                                                                                              ©TBS 1999 – All rights reserved  Table 1 – Nominal rim diameter code  
 
 
Nominal rim diameter code  Nominal rim diameter  
 
10 
12 
13 
14 
15 
16 
17 
18 
19 
  
254 
305 
330 
356 
381 
406 
432 
457 
483 
 
 
 
 
 5.2 Service description  
 
The service description shall be indicated as follows:   
 
Load index speed symbol  
 
For the  special case of tyres designed for vehicles having a maximum speed capability more 
than 3 00 km/h, the indication of the service description is not required.  For the maximum 
speed capability and the lead capacity of the tyres, the tyre manufacturer concerned shall be 
consulted.  
 
5.2.1    Load Index  
 
The maximum tyre load capacity corresponding to the service conditions specified by the tyre 
manufacturer shall be indicated by a load index taken form Table 2.  This indication is 
understood to be per tyre for a single mounting.  Guidelines for load capacities for passenger 
car tyres are given in An nex B.  
 
5.2.2 Speed symbol  
 
The speed  category is assigned to a tyre to denote the maximum speed for which use of the 
tyre is rated.  
 
The speed symbol shall be indicated by a letter taken form Table 3 corresponding to the 
speed category.  
 
Maximum inflatio n pressure  
 
 Operating cold inflation pressures should be agreed between tyre and vehicle manufacturers 
taking into account not only the tyre load carrying capacity, but also the operating conditions, 
the maximum speed, the position of the tyre on the vehi cle, service conditions and 
construction and characteristics of the vehicle.  
 
 Unless otherwise specified by the tyre manufacturer, it is recommended to limit  the cold 
inflation pressure of the radial ply tyres in normal application to 350 kPa for all sta ndard load 
version sizes on code designated rims irrespective of the  speed symbol.  
  
Other choices of pressure specifications may be 240, 280, 290, 300, 330, 340 and 390 kPa. 
The marking shall be followed in parenthesis by the equivalent inflation pressur e in psi, 
rounded to the next higher whole number.  The vice versa marking is also permitted.  
  
©TBS 1999 – All rights reserved                                                                                              5 5.3 Other service characteristics   
 
5.3.1  The word “TUBELESS” shall appear on the tyres that can be used without a tube.  
 
 5.3.2  The letter  “T” immediately in front of the tyre size designation shall be used to 
characterize high pressure special temporary  use spare tyres.     
 
5.3.3  A tread wear indicator shall be incorporated, that will provide a visual indication that the 
tyre has worn to a tread depth of 1.6  mm. 
 
5.3.4  The generic name of each cord material used in the plies (both sidewall and tread area) 
of the tyre shall be marked.   
 
 5.3.5  Ply rating or number of plies in the sidewall and the number of plies in the tread area, if 
different.    
 
5. 3. 6  Each tyre shall be labelled with the name of the manufacturer, or brand name 
recognized quality mark/safety mark to show that the tyre conforms to respective national 
standards. The tyre may also be marked with any other identification assigned to the 
manufa cturer.  
 
 5.3.7  Specific indications, if required may be added to indicate  
 
 
a) the type of vehicle  for which the tyre  is primarily designed, using the symbol, “P”.  
This symbol may be used where there may be ambiguity regarding the tyre type.  
Where this optional marking is used, it should be so positioned that confusion cannot 
result from its proximity to any other service condition marking;  
  
 
 
b) the temporary  use of certain spare tyres using indications such as “TEMPORARY 
USE ONLY”;  
 
c) the bias -belted cons truction with the words “BIAS - BELTED”;  
 
d)  the radial ply construction with  the word “RADIAL”;  
 
e) the direction of mounting;  
 
f) the direction  of rotation  
 
g) the type of tread pattern and any other characteristics.  
 
5.3.8 Tyre covered under this specification s hall not be more than 8 years from the date of 
manufacture.  
 
 
 
 
 
 
 
 
 
 
 
 
 
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                
6                                                                                              ©TBS 1999 – All rights reserved  Table 2 – Correlation between load index LI and tyre load -carrying capacity TLCC  
 
 
LI  
TLCC  
kg  
LI  
TLC  
TLCC  
kg  
LI  
TLCC  
  
TLCC  
kg 
 
50 
51 
52 
53 
54 
55 
56 
57 
58 
59 
 
60 
61 
62 
63 
64 
65 
66 
67 
68 
69 
  
190 
195 
200 
206 
212 
218 
224 
230 
236 
243 
 
250 
257 
265 
272 
280 
290 
300 
307 
315 
325  
70 
71 
72 
73 
74 
75 
76 
77 
78 
79 
 
80 
81 
82 
83 
84 
85 
86 
87 
88 
89  
335 
345 
355 
365 
375 
387 
400 
412 
425 
437 
 
450 
462 
475 
487 
500 
515 
530 
545 
560 
580  
90 
91 
92 
93 
94 
95 
96 
97 
98 
99 
 
100 
101 
102 
103 
104 
105 
106 
107 
108 
109  
600 
615 
630 
650 
670 
690 
710 
730 
750 
775 
 
800 
825 
850 
875 
900 
925 
950 
975 
1000  
1030  
  
110 
111 
112 
113 
114 
115 
116 
117 
118 
119 
 
120  
1060  
1090  
1120  
1150  
1180  
1215  
1250  
1285  
1320  
1360  
 
1400  
 
 
 
 
 
 
 
NOTES  
 
1) The load capacity correspon ding to the load index applies for speeds up to and 
including 210 km/h.   
 
For speed symbol V tyres (between 210 km/h and 240 km/h), the maximum load 
capacity per tyre is to be reduced to the value corresponding to the following 
percentages:  
 
100% at 210 k m/h, 97% at 220 km/h, 94% at 230 km/h, 91% at 240 km/h. Between 
these speeds, linear interpolation is permitted.  
 
2) In the case of speed symbols W and Y, the maximum load capacity per tyre 
corresponding to the load index applies for speeds up to and inclu ding 240 km/h for W 
and 270 km/h for Y. 
 
For speed symbol W tyres between 240 km/h and 270 km/h, the maximum load capacity per 
tyre is to  be reduced to the value corresponding to the following percentages:  
 
100% at 240 km/h, 95% at 250 km/h, 90% at 260 km /h, 85% at 270 km/h. Between these 
speeds, linear interpolation is permitted.  
 
For ZR marked tyres and/or for speeds over 300 km/h, consult the tyre manufacturer 
concerned for the maximum tyre load capacity permitted in relation to the maximum speed 
allowe d for the tyre.  
 
 
 
  
©TBS 1999 – All rights reserved                                                                                              7 Table 3 - Correlation between speed symbol and speed category  
 
Speed  
symbol  Speed category  
km/h  
 
J 
K 
L 
M 
N 
P 
Q 
R 
S 
T 
U 
H 
V 
W 
Y  
100 
110 
120 
130 
140 
150 
160 
170 
180 
190 
200 
210 
240 
270 
300 
 
 
 
 
Radial ply tyres designed for operation at speeds in excess of 300 km/h are to be identified by 
means of code -letters ZR in the “dimensional and constructional” characteristics in place of 
the tyre construction code.  For these tyres, consult the tyre manufacturers concerned for the 
maximum spee d capability.  
 
6 Marking  
 
Each tyre shall conform to each of the following marking requirements:  
 
a) the designation of the size and construction as in 5.1;    
b) the designation of service condition characteristics as in 5.2;  
c) the designation of other service  characteristics as in 5.3.  
 
The location of the marking of the load and speed characteristics shall be distinct, but near 
the marking of the size and construction.  In no cases shall the information be positioned on 
the tyre so that it is obstructed by th e flange or any rim designated for use with that tyre.  
 
6.1 Example 1  
 
A tyre having  
a) a size contraction of:  
 
i) nominal section width 165 mm;  
ii) nominal aspect ratio 80;  
iii) radial ply construction;  
iv) nominal rim diameter code 15.  
 
b) service description of ;  
 
h) load index LI 87, corresponding to a tyre load -carrying capacity of 545 kg. – speed 
symbol  H, corresponding to a speed category of 210 km/h.  
 
 
 
 
 
 
  
8                                                                                              ©TBS 1999 – All rights reserved  c) other service characteristics:  
 
i) TUBELESS : tyre to be used without a tube; shall be marked as follow s:  
 
   165.80 R 15 87 H  
   TUBELESS  
 
 
NOTE  – See Annex D for other existing size markings.  
 
 
6. 2 Example 2  
 
A tyre marked 225/45 ZR 16 has the following characteristics:  
 
a) nominal section width 225 mm;  
b) nominal aspect ratio 45;  
c) radial ply construction ty re designed for  operations at speeds in excess of 240 km/h  
(code letters “ ZR”); 
d)  nominal rim diameter code corresponding to 406 mm (code 16).  
 
 
NOTE – See Annex C for special cases of radial tyres designed for speeds in 
excess of 210 km/h.  
 
7 Tyre dimens ions   
 
Except for the cases in 7.1.1   and 7.1.2, the formula derived values for tyre dimensions are to 
be rounded off to the nearest millimeter. For rounding off, see TZS 4 1979 (see clause 3).  
 
NOTE  – Dimensions are expressed in millimetres.  
 
 7.1 Calcul ation of “design tyre” dimensions  
 
7.1.1  Theoretical rim width, R th 
 
 The theoretical rim width, R th  is equal to the product of the nominal section width, SN,  and 
the rim/section ratio,  K,  
 
 R th = K1 SN 
 
    
For tyres mounted on 5° rims (code – designated) with nominal rim diameter expressed by a 
two figure code,  
 
 K1 = 0.7 for tyres having nominal aspect ratio ( H/S) from 50 to 95 inclusive;  
 K1 = 0.85 for tyres having nominal aspect ratio ( H/S) from 30  to 45 inclusive;  
 
 
7.1.2    Measuring rim wid th, R m 
 
The measuring rim width, Rm, is equal to the product of the nominal section width, SN and the 
rim/section width ration coefficient, K2: 
 
 
 Rm = K2 SN 
 
 
Rounded to the nearest standardized rim.  
  
©TBS 1999 – All rights reserved                                                                                              9 For tyres mounted on 5° drop -centre rims with a nomina l diameter expressed by a two -figure 
code;  
 
 K2 = 0.7 for nominal aspect ratios ( H/S) 95 to 75 inclusive;  
 K2 = 0.75 nominal aspect ratios ( H/S) 70 to 60 inclusive;  
 K2 = 0.8 or nominal aspect ratios ( H/S) 55 to 50;  
 K2 = 0.85 for nominal aspect ratio ( H/S) 45; 
 K2 = 0.9 for nominal aspect ratios ( H/S) 40 to 30 inclusive.  
 
 
7.1.3  Design tyre section width, S  
 
The design tyre section width, S is the nominal section width, SN, transferred from the 
theoretical rim, Rth to the measuring rim, Rm. 
 
 
S = SN + 0.4  (Rm – Rth ) 
 
where  Rm and R th are expressed in millimetres.  
 
 7.1.4  Design tyre section height, H  
 
The design section height, H, is equal to the product of the nominal section width, SN, and the 
nominal aspect ratio, H/S divided by 100:  
 
 
   SN H/S 
H =  
    100 
 
 
NOTE –H/S = nominal aspect ratio.  
 
 7.1.5  Design tyre overall diameter, D o 
 
 The design tyre overall diameter, Do is the sum of the nominal rim diameter, Dr, plus twice the 
design tyre section height, H. 
 
 
 Do = Dr + 2H 
 
For those tyres using a  nominal rim diameter code, the corresponding value of Dr given in 
Table 1 is to be used.  
 
7.1.6  Guidelines   
 
Guidelines   for “tyre design dimensions” for the metric series of passenger car tyres mounted 
on 5° rims (code -designated) are given in Annex A. Table 5 presents a guide relating to the 
determination of the appropriate rim widths for a given tyre.  
 
 
7.2 Calculation of “maximum overall (grown) tyre dimension in service” for tyres 
mounted on their measuring rims  
 
This calculation is for use by vehicl e manufacturers in designing for tyre clearance.   
 
These dimensions are to be calculated with the coefficients (see Table 4) appropriate to the 
design tyre section width and the design tyre section height.  
 
7.2.1  Maximum overall (grown)  width in service , W max.  
10                                                                                              ©TBS 1999 – All rights reserved   
The maximum overall (grown) width in service, Wmax is equal to the greater of the following 
values:  
 
a) the product of the design tyre section width S  and the appropriate coefficient a (see 
Table 4);  
 
 
Wmax = Sa  
 
b) the addition of 8 mm to the design tyre section width, S:  
 
Wmax = S + 8 
 
 
 
 Table 4 – Coefficients for calculation of the tyre dimensions  
  
 
Structure   
Tyre  
construction 
code   
Nominal 
aspect ratio 
H/S  
Coefficients  
 
 
a  
b  
c  
d 
 
 
Diagonal  
  
D  
 
All  
 
1.1  
 
1.08  
-   
- 
 
Bias-belte d 
  
B  
-   
- 
 
 
 
Radial ply   
 
 
R  
≤ 65  
1.04 
  
 
 
 
 
1.04  
 
 
 
 
0.96  
 
 
 
 
0.97  
 70  
1.04 
 
 
≥ 75  
1.06 
 
 
 
 
NOTE  – The maximum overall section width may be exceeded by the thickness of a 
special protective rib on one sidewall.  
 
 
7.2.2  Maximum overall (grown) diameter in service, D o max, is equal to the nominal rim 
diameter, Dr, plus twice the product of the design tyre section height H, and the appropriate 
coefficient b, (see Table 4).  
 
D o max = Dr + 2Hb 
 
 7.3 Calculation of minimum tyre dime nsions for radial ply tyres mounted on their 
measuring rims  
 
 7.3.1  Minimum tyre section width, S min    
  
The minimum tyre section width, S min, is equal to the product of the design tyre section width, 
S, and the coefficient c (see Table 4).   
  
©TBS 1999 – All rights reserved                                                                                              11  
S min = Sc 
 
7.3.2  Minimum tyre overall diameter , D o min 
 
The minimum tyre overall diameter, D o min, is equal to the nominal rim diameter, Dr, plus twice 
the product of the design tyre section height, H, and the coefficient d (see Table 4).  
 
 
D o min = Dr + 2Hd 
 
7.4 Range of approved rims  
 
7.4.1  The range of approved rim widths is calculated as the product of the nominal section 
width, SN, and the coefficients shown in Table 5.  The values obtained shall be rounded to the 
nearest standardized rim width.  
 
7.4.2  The maximum overall grown width in service, W max and the minimum tyre section width, 
S min, will change by 40% of the change in rim width, expressed in millimetres.  
 
 
Table 5 – Approved rim widths for passenger car tyres as a function of nominal aspect 
ratio  
 
 
 
Nominal aspect ratio H/S  
  
Coefficients for calculation of approved rim width  
 
 
min 
  
max.  
  
70 ≤ 95 
50 ≤ 65  
H/S = 45 
35 = H/S ≤ 40  
H/S = 30 
  
0.65 
0.7 
0.8 
0.85 
0.9  
0.85 
0.9 
0.95 
1 
1 
 
 
8 Tyre dimension presentation  
 
Tyre dimensions shall be shown in tables.  An example for tyres mounted on 5° rims (code - 
designated) and nominal rim diameter expres sed by a two -figure code is given in Table 6.  
 
 
Table 6 – Example of tyre dimension table  
 
 
 
Tyre  
size 
designation   
Measuring 
rim  
code   
Design dimensions   
Maximum dimensions in 
service  (grown)  
 
 
Section  
width  
mm  
Overall 
diameter  
D o mm  
Overa ll  
width  
W max mm   
Overall 
diameter  
D o max mm 
 
      
 
 
  
12                                                                                              ©TBS 1999 – All rights reserved  9   Test requirements  
 
9.1    Test sample  
 
The test sample shall constitute  
 
9.1.1   one tyre for physical dimensions, resistance to bead unseating, and strength in 
sequence;  
 
9.1.2  another ty re for endurance test; and  
 
9.1.3  a third tyre for high -speed performance.  
 
 
9.2 Physical dimensions measurement   
 
The tyre physical dimensions shall be determined under uniform ambient conditions anis 
follows:  
 
9.2.1  The sample shall be mounted on a recom mended test rim for that tyre size designation 
and inflated to the applicable pressures recommended in Table 7.  Then the tyre shall be 
conditioned at ambient room temperature for a minimum of 24 h and the pressure re -adjusted 
to the original value.  
 
9.2.2  The section width and overall are callipered at six points approximately equally spaced 
around the tyre circumference.  The average of the measurements as the section width and 
overall width, respectively; is recorded.  
 
9.2.3  The tyre overall diameter is determined by measuring the maximum circumference of 
the tyre and dividing this dimension by π = 3.1416.  
 
The actual section width and overall width for  each tyre measured in accordance with this 
procedure shall not exceed the section width specified in the submission made   by the 
manufacturer or in any standard tyre and rim matching information ; for its size designation 
and type, by more than 7%.  
  
 
Table 7 – Recommended pressures for measurement of tyre dimensions  
 
 
Tyre    
Pressure (kPa)  
 
 
Standard load version  
 
 Extra load/reinforced version  
 
 “Type” temporary -use spare tyre   
180 
 
 230 
 
 420 
 
 
 
 
 
9.3 Tubeless tyre bead unseating resistance  
 
9.3.1  Preparation of tyre -wheel assembly    
 
The tyre is washed, dried at the beads and mount without lubrication or adhesives on a clean, 
painted test rim.  The tyre is then inflated to the applicable pr essure specified in Table 8 at  
©TBS 1999 – All rights reserved                                                                                              13 ambient room temperature.  The tyre -wheel assembly is mount on a fixture against the tyre 
side wall as required by the geometry of the fixture.  
 
 
9.3.2 Test procedure   
 
a) Load is applied through the block to the tyre outer side wall at the specified distance 
for the applicable wheel size at a rate of 50 mm per minute, with the load arm 
substantially parallel to the tyre and rim assembly at the time of engagement.  
 
b) The load is increased until the bead unseats or the applicable spe cified value is 
reached (see Table 8).  The applied force required to unseat the tyre bead at the 
point of contact shall be not less than the specified one.  
 
c)  The test is repeated at at least four places equally spaced around the tyre 
circumference.  
 
 
Table 8 – Specified values for bead unseating test  
 
  
 
Max.  inflation 
pressure ( kPa)   
Section width  (mm)   
Load rating (kg)   
Applied force  
required to unseat 
the (bead kN) min  
 
Other than  
 420 
  
SN < 155  
155 ≥ SN < 205  
SN ≥ 205   
- 
- 
- 
  
6.7 
8.9 
11 
 
 
420  
- 
- 
-  
< 400  
400 ≥ LR  > 650  
LR ≥ 650   
6.7 
8.9 
11 
 
 
 
 9.4 Tyre strength   
 
 9.4.1  Requirement  
 
Each tyre shall need the requirements for maximum breaking energy specifed in Table 9 
when tested according  to 9.4.3.  
 
 
9.4.2  Preparation of tyre  
 
The tyre is mount on a test rim and inflated to the applicable pressure specified in Table 11.  It 
is then conditioned at room temperature for at least 3 h and the pressure is readjusted to the 
original value.  
 
 9.4.3 Test procedure  
 
A 20 mm diameter cylindrical steel plunger is forced, with a hemispherical end perpendicularly 
into the tread rib as near to the centre line as possible, avoiding penetration into the tread 
groove, at the rate of 50 mm per minute.  
 
 The force and penetration at five test points equally spaced around the circumference of the 
tyre are recorded.  If the tyre fails to break before the plunger is stopped by reaching the rim,  
14                                                                                              ©TBS 1999 – All rights reserved  the force is recorded and the values are used in computing the breaki ng energy for each test 
point by means of the following formula:  
 
 
 
  F x P 
W =   
2000  
 
 
where  
 
 W = energy in J  
 F = force in N  
P = penetration in mm  
 
 
The breaking energy for the tyre is determined by computing the average of the five values 
obtained  above.   
 
 
Table 9  – Minimum breaking energy (Joules) – tyre strength tests  
 
A) For bias ply tryes with designated section width of 155 mm and above.  Maximum 
permissible   inflation pressure.  
 
 
 
Cord material  
  
220.48 (kPa)   
248.04 
(kPa)   
275.6 
(kPa)  
  
240 (kPa)   
280 (kPa)   
300 
(kPa)   
340 (kPa)  
 
Rayon  
  
11368.5   
1773.8   
22737   
11368   
22737   
11368.5   
22737  
 
Nylon or 
polyester  
  
 
 17914   
 
26891   
  
35828   
 
17914   
 
35828   
 
17914   
 
35828  
 
 
 
B) For bias ply tyres with designated section width below 155 m m. Maximum permissible 
inflation pressure  
 
    
 
Cord material  
  
220.48 (kPa)   
248.04 
(kPa)   
275.6 
(kPa)  
  
240 (kPa)   
280 (kPa)   
300 
(kPa)   
340 (kPa)  
 
Rayon  
  
6890   
12918.75   
17225   
6890   
17225   
6890   
17225  
 
Nylon or 
polyester  
  
 
13435.5   
20153.2   
2687 1  
13435.5   
26871   
13435.5   
26871  
 
 
 
 
 
 
 
 
C) For radial ply tyres.  Maximum permissible inflation pressure  
   
©TBS 1999 – All rights reserved                                                                                              15  
 
 
Size 
designation 
below 160 
mm  
Tyre other than CT   
CT tyres  
 
 
psi  
kPa  
kPa 
 
 
32  
36  
40  
240  
280  
300  
340  
350  
290  
330  
350  
390 
 
 
2205   
3305   
4405   
2205   
4405   
2205   
4405   
2205   
2205   
4405   
2205   
4405  
 
  
160 mm or 
above   
290  
4405   
5905   
2905   
5905   
2905   
5905   
2905   
2905   
5905   
2905   
5905  
 
 
 
D) For tyres with 413.4 kPa maximum permissible inflation pressure and maximum load ratin g 
of 399 kg and above  
 
 
 
Cord material   
Breaking energy (J)  
 
  
Rayon   
186.45  
 
 
Nylon or polyester    
293.8  
 
 
E) For tyres with 413 kPa maximum permissible inflation pressure and 399 kg maximum load 
rating and below  
 
 
 
Code material   
Breaking energy (J)  
 
 
Rayon   
1130  
 
 
Nylon or polyester   
220.35  
 
 
9.5 Tyre endurance  
 
9.5.1  Requirement  
 
 
When the tyre has been subjected  to the laboratory endurance test specified in 9.5.3,  using 
a test rim that undergoes no permanent deformation and allows no los s of air through the 
potion that it comprises of the tyres rim pressure chamber;  
 
a) there shall be no visual evidence of tread sidewall, ply cord, innerliner or bead 
separation,  chunking, broken cords, cracking or open splices and  
 
b) the tyre pressure at the  end of the test shall be not less than the initial pressure 
specified in Table 11.  
  
16                                                                                              ©TBS 1999 – All rights reserved   9.5.2 Preparation of tyre   
 
The tyre is mount on a test rim and inflated to the pressure specified in Table 11.  
 
The tyre assembly is conditioned to 38  ± 2°C for at leas t 3 h then the pressure is readjusted 
to the initial value immediately before testing.  
 
9.5.3  Test procedure   
 
The tyre – wheel assembly is mount on a test axle and pressed against a flat -faced steel test 
wheel, with the applicable test load specified in T able 10 for the tyre size, designation type, 
and max.  permissible inflation pressure.  
 
During the test, the air surrounding the test area shall be kept at 38  ± 2°C.  
 
The test is then conducted at 80 km/h without pressure adjustment or other interruption s as 
follows:   
 
The loads for the following periods are specified percentage of the maximum load rating 
marked on that tyre sidewall.  
 
 
Table 10 – Percentage of maximum load rating   
 
  
 
4h 
6h 
24h  
85% 
90% 
100%  
 
 
 
Immediately after the tyre is run the re quired time, the inflation pressure is measured.  The 
tyre is then allowed to cool for one hour, deflated, removed from the test rim and inspected for 
the conditions specified in 9.5.1 (a).  
 
Table 11 – Test inflation pressures  
 
  
 
Test type max, 
inflation  pressure  
 Tyre other than CT 
kPa CT tyres  
kPa 
 
 
240  
280  
300  
340  
350  
290  
330  
350  
390 
 
 
Bead unseating, 
tyre strength and 
tyre endurance  
  
 
180  
 
220  
 
180  
 
220  
 
180  
 
230  
 
270  
 
230  
 
270 
  
High speed 
performance  
  
 
220  
 
260  
 
220  
 
260  
 
220  
 
270  
 
310  
 
270  
 
310 
 
 
 
 
9.6 High -speed performance   
  
©TBS 1999 – All rights reserved                                                                                              17 9.6 1  Requirements  
 
When the tyre has been subjected to the laboratory high -speed performance test specified in 
9.6.3  using a test rim that undergoes no permanent deformation and allows no lo ss of air 
through the portion that it comprises of a tyre -rim pressure chamber, the tyre shall meet the 
requirements set forth in 9.5.1 (a) and (b).  
 
9.6.2  Preparation  of tyre   
 
As described in 9.5.2.  
 
 9.6.3  Test procedure   
 
The tyre and wheel assembly is  mount in accordance with 9.5.3 and pressed against the test 
wheel with a load of 88% of the tyre's maximum load rating as marked on the tyre sidewall; then 
is run for two hours at 80 km/h.  The tyre is allowed to cool to 38  ± 2°C and the pressure is 
readjusted  to the applicable pressure specified in Table 11.  
 
 
Then without readjusting inflation pressure, the tyre is tested at 120 km/h for 30 minutes, 130 
km/h for 30 minutes and 140 km/h for 30 minutes.  
 
 Immediately after running the tyre the required t ime, the inflation pressure is measured and  
inspected for the conditions specified in 9.5.1 (a).  
 
10 Non – conforming tyres   
 
No tyre that is designed and manufactured for use on passenger cars, that does not conform to 
the requirements of this standard s hall be sold, offered for sale, introduced or delivered for 
introduction into,  or imported into the United Republic of Tanzania for any purpose.  
 
 
Annex A  
 
(normative)  
 
Guidelines for design tyre dimensions (metric series) mounted on 5° rims (code -design ated) 
with nominal rim diameter expressed by a two -figure code are given in tables A.1 to A. 7 as a 
function of nominal aspect ratio.  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           
Table  A.1 – H/S of 95 to 75 inclusive  (K1 = 0,7; K2 = 0,7)  
  
18                                                                                              ©TBS 1999 – All rights reserved  Nominal 
section  
width  
  
SN 
 
 
mm Measuring rim 
width  Design tyre dimensions, mm  Approved rim 
width codes  
 
 
(Rm) 
 
 
code         mm  Section 
width  
 
 
 
S  
Section height, H, nominal aspect rations , H/S  (%) 
of  
 
 
  95            90               85                 80         75   
 
 
 
min  
 
 
 
max 
 
95 
 
105 
 
115 
 
125 
 
135 
 
145 
 
155 
 
165 
 
175 
 
185 
 
195 
 
205 
 
215 
 
225 
 
235 
 
245 
 
255 
 
265 
 
275 
 
285 
 
295 
 
305 
 
315 
  
2.5 
 
3.0 
 
3.0 
 
3.5 
 
3.5 
 
4.0 
 
4.5 
 
4.5 
 
5.0 
 
5.0 
 
5.5 
 
5.5 
 
6.0 
 
6.0 
 
6.5 
 
7.0 
 
7.0 
 
7.5 
 
7.5 
 
7.0 
 
8.0 
 
8.0 
 
8.5 
  
63,5 
 
76 
 
76 
 
89 
 
89 
 
101,5  
 
114,5  
 
114,5  
 
127 
 
127 
 
139,5  
 
139,5  
 
152,5  
 
152,5  
 
165 
 
178 
 
178 
 
190,5  
 
190,5  
 
203 
 
203 
 
216 
 
216  
94 
 
106 
 
113 
 
126 
 
133 
 
145 
 
157 
 
165 
 
177 
 
184 
 
196 
 
203 
 
216 
 
223 
 
235 
 
248 
 
255 
 
267 
 
274 
 
286 
 
294 
 
306 
 
313  
90 
 
100 
 
109 
 
119 
 
128 
 
138 
 
147 
 
157 
 
166 
 
176 
 
185 
 
195 
 
204 
  
86 
 
95 
 
104 
 
113 
 
122 
 
131 
 
140 
 
149 
 
158 
 
167 
 
176 
 
185 
 
194 
 
203 
  
81 
 
89 
 
98 
 
106 
 
115 
 
123 
 
132 
 
140 
 
149 
 
157 
 
166 
 
174 
 
183 
 
191 
 
200 
 
208  
76 
 
84 
 
92 
 
100 
 
108 
 
116 
 
124 
 
132 
 
140 
 
148 
 
157 
 
164 
 
172 
 
180 
 
188 
 
196 
 
204  
71 
 
79 
 
86 
 
94 
 
101 
 
109 
 
116 
 
124 
 
131 
 
139 
 
146 
 
154 
 
161 
 
169 
 
176 
 
184 
 
191 
 
199 
 
206 
 
214 
 
221 
 
229 
 
236  
2.5 
 
2.5 
 
3.0 
 
3.0 
 
3.5 
 
3.5 
 
4.0 
 
4.0 
 
4.5 
 
4.5 
 
5.0 
 
5.0 
 
5.5 
 
6.0 
 
6.0 
 
6.5 
 
6.5 
 
7.0 
 
7.0 
 
7.5 
 
7.5 
 
8.0 
 
8.0 
  
3.0 
 
3.5 
 
4.0 
 
4.0 
 
4.5 
 
5.0 
 
5.0 
 
5.5 
 
6.0 
 
6.0 
 
6.5 
 
7.0 
 
7.0 
 
7.5 
 
8.0 
 
8.0 
 
8.5 
 
9.0 
 
9.0 
 
9.5 
 
10.0 
 
10.0 
 
10.5 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Table A.2  - H/S of 70 (K 1 = 0,7; K 2 = 0,75)  
  
©TBS 1999 – All rights reserved                                                                                              19  
 
Nominal 
section 
width  
 
 
SN 
 
mm  
Measuring rim  
width  
 
 
(Rm) 
 
 
Code                    mm    
Design tyre dimensions, 
mm   
 
Appro ved rim width  
codes   
 
 
 
 
Min                          max   
 
Section 
width  
 
S  
 
Section 
height  
 
 H  
 
95 
 
105 
 
115 
 
125 
 
135 
 
145 
 
155 
 
165 
 
175 
 
185 
 
195 
 
205 
 
215 
 
225 
 
235 
 
245 
 
255 
 
265 
 
275 
 
285 
  
         3.0 
 
3.0 
 
3.5 
 
3.5 
 
4.0 
 
4.5 
 
4.5 
 
5.0 
 
5.0 
 
5.5 
 
6.0 
 
6.0 
 
6.5 
 
6.5 
 
7.0 
 
7.0 
 
         7.5 
 
8.0 
 
8.0 
 
         8.5  
76 
 
76 
 
89 
 
89 
 
101,5  
 
114,5  
 
114,5  
 
127 
 
127 
 
139,5  
 
152,5  
 
152,5  
 
165 
 
165 
 
178 
 
178 
 
190,5  
 
203 
 
203 
 
216  
99 
 
106 
 
118 
 
126 
 
138 
 
150 
 
157 
 
170 
 
177 
 
189 
 
201 
 
209 
 
221 
 
228 
 
240 
 
248 
 
260 
 
272 
 
279 
 
292 
  
67 
 
74 
 
81 
 
88 
 
95 
 
102 
 
109 
 
116 
 
123 
 
130 
 
137 
 
144 
 
151 
 
158 
 
165 
 
172 
 
179 
 
186 
 
193 
 
200  
2.5 
 
2.5 
 
3.0 
 
3.0 
 
3.5 
 
3.5 
 
4.0 
 
4.0 
 
4.5 
 
4.5 
 
5.0 
 
5.0 
 
5.5 
 
6.0 
 
6.0 
 
6.5 
 
6.5 
 
7.0 
 
7.0 
 
7.5  
3.0 
 
3.5 
 
4.0 
 
4.0 
 
4.5 
 
5.0 
 
5.0 
 
5.5 
 
6.0 
 
6.0 
 
6.5 
 
7.0 
 
7.0 
 
7.5 
 
8.0 
 
8.0 
 
8.5 
 
9.0 
 
9.0 
 
9.5 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
20                                                                                              ©TBS 1999 – All rights reserved  Table A.3  - H/S of 65 and 60 (K1 = 0,7; K2 = 0.75)  
 
 
Nominal 
section 
width  
 
 
SN 
 
mm  
Measuring rim  
width  
 
 
(Rm) 
 
 
Code                  mm   
Design tyre dimensions, mm  
   
 
Approved rim width  
codes   
 
 
 
 
min                  max   
 
Section 
width  
 
   S  
Section height, H,  at 
nominal aspect ratios , H/S 
(%) of  
 
 
      65                 60  
 
105 
 
115 
 
125 
 
135 
 
145 
 
155 
 
165 
 
175 
 
185 
 
195 
 
205 
 
215 
 
225 
 
235 
 
245 
 
255 
 
265 
 
275 
 
       285 
 
295 
 
305 
 
315 
 
325 
 
335 
 
345 
  
3.0 
 
3.5 
 
3.5 
 
4.0 
 
4.5 
 
4.5 
 
5.0 
 
5.0 
 
5.5 
 
6.0 
 
6.0 
 
6.5 
 
6.5 
 
7.0 
 
7.0 
 
7.5 
 
8.0 
 
8.0 
 
8.5 
 
8.5 
 
9.0 
 
9.5 
 
9.5 
 
10.0 
 
10.0 
  
76 
 
89 
 
89 
 
101,5  
 
114,5  
 
114,5  
 
127 
 
127 
 
139,5  
 
152,5  
 
152,5  
 
165 
 
165 
 
178 
 
178 
 
190,5  
 
203 
 
203 
 
216 
 
216 
 
228,5  
 
241,5  
 
241,5  
 
254 
 
254  
106 
 
118 
 
126 
 
138 
 
150 
 
157 
 
170 
 
177 
 
189 
 
201 
 
209 
 
221 
 
228 
 
240 
 
248 
 
260 
 
272 
 
279 
 
292 
 
299 
 
311 
 
323 
 
331 
 
343 
 
350 
  
68 
 
75 
 
81 
 
88 
 
94 
 
101 
 
107 
 
114 
 
120 
 
127 
 
133 
 
140 
 
146 
 
153 
 
159 
 
166 
 
172 
 
179 
 
185 
 
192 
 
198 
 
205  
 
 
69 
 
75 
 
81 
 
87 
 
93 
 
99 
 
105 
 
111 
 
117 
 
123 
 
129 
 
135 
 
141 
 
147 
 
153 
 
159 
 
165 
 
171 
 
177 
 
183 
 
189 
 
195 
 
201 
 
207  
3.0 
 
3.0 
 
3.5 
 
3.5 
 
4.0 
 
4.5 
 
4.5 
 
5.0 
 
5.0 
 
5.5 
 
5.5 
 
6.0 
 
6.0 
 
6.5 
 
7.0 
 
7.0 
 
7.5 
 
7.5 
 
8.0 
 
8.0 
 
8.5 
 
8.5 
 
9.0 
 
9.0 
 
9.5  
3.5 
 
4.0 
 
4.5 
 
5.0 
 
5.0 
 
5.5 
 
6.0 
 
6.0 
 
6.5 
 
7.0 
 
7.5 
 
7.5 
 
8.0 
 
8.5 
 
8.5 
 
9.0 
 
9.5 
 
9.5 
 
10.0 
 
10.5 
 
11.0 
 
11.0 
 
11.5 
 
12.0 
 
12.0 
 
 
 
 
 
 
 
 
 
 
Table A.4  - H/S of 55 and 50 (K1 = 0,7; K2 = 0,8)  
  
©TBS 1999 – All rights reserved                                                                                              21  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Table A.5  – H/S of  45 (K1 = 0,85; K2 = 0,85)   
22                                                                                              ©TBS 1999 – All rights reserved   
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Table A.6   - H/S of 40 and 35 (K 1 = 0,85; K 2 = 0,9)   
©TBS 1999 – All rights reserved                                                                                              23  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Table A 7  - H/S of 30 (K1 = 0,85;  K2 = 0,9)  
  
24                                                                                              ©TBS 1999 – All rights reserved  
 
 
 
 
 
 
 
 
 
 
 
 
 
Annex B   
  
©TBS 1999 – All rights reserved                                                                                              25 (normative)  
 
Load capacity indices for passenger car tyres  
 
 Tables B.1  to B.4 show equivalences, based on overall diameter, for tyres in standard load 
version.  
 
 Load -carrying capacity indices are referred to a basic inflation pressure of 240  
 kPa.  Load indices given are preferred values for international use.  Sizes given in parentheses 
are  those for tyres equivalent in overall diameter which have higher load capacity indices.  
 
Table B.5 gives tyres load capacity indices, grouped by nominal r im diameter and nominal 
aspect ratio, referred to a basic pressure of 240  kPa for the standard load version.  
 
 
NOTE – For future revisions of the values in Table B.5, it is recommended that all 
values be increased by the same amount.  
 
 
Table B.6 gives the  load capacity indices for T -type temporary spare tyres, with a reference 
pressure of 420 kPa.  
 
 
 
 
Table B.1  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Table B.2  
  
26                                                                                              ©TBS 1999 – All rights reserved  
 
 
 
Table B.3  
 
 
 
 
 
 
 
 
 
 
 
 
Table B.4  
  
©TBS 1999 – All rights reserved                                                                                              27 
 
 
Table B. 5 
 
 
 
 
 
 
 
  
28                                                                                              ©TBS 1999 – All rights reserved  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
©TBS 1999 – All rights reserved                                                                                              29 
 
 
 
 
 
 
  
30                                                                                              ©TBS 1999 – All rights reserved  
 
 
 
 
 
 
 
 
 
 
 
  
©TBS 1999 – All rights reserved                                                                                              31  
 
 
Annex C  
 
(informative)  
 
Marking of radial tyres designed for vehicle with maximum speeds above 
210 km/h  
 
   
The code letters “ VR” ma y be used within the dimensional and constructional characteristics in 
place of the tyre construction code for radial ply tyres designed for equipment on some existing 
vehicles with maximum speeds above 210   km/h.  
 
Example  
 
 215 /60 VR 15  
 
 This preclude s the marking of service description.  For the maximum  speed capability and the 
load capacity of the tyres, the tyre manufacturer concerned shall be consulted.  
 
C.2 The code letters “ZR” may be used within the dimensional and constructional 
characteristic s in place of the tyre construction code for radial ply tyres designed to equip some 
existing vehicles with maximum speeds above 240 km/h.  
 
Example  
 
205/50 ZR 16   
 
This precludes the marking of service description. For the maximum speed capability and th e 
load capacity of the tyres, the tyre manufacturer concerned shall be consulted.  
 
 C.3 The code letters “ZR” may be used within the dimensional and constructional 
characteristics, in place of the tyre construction code (see 5.1.3) and in conjunction with “W” 
speed symbol and load index to identify tyre performances up to 270 km/h.  
 
Example  
 
195/50 ZR 15 82W  
 
C.4 The code -letters “ZR” may be used in the dimensional and constructional characteristics  
(see 5.1.3)  associated with the speed code Y and the loa d index to identify tyre performances 
up to 300 km/h.  
 
Example  
 
195/50 ZR 15 82Y  
 
 
 
 
 
 
 
 
 
 
  TZS 618: 1999                                                               
 
 
©TBS 1999 – All rights reserved