1、SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirelyvoluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefro
2、m, is the sole responsibility of the user.”SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions.QUESTIONS REGARDING THIS DOCUMENT: (724) 772-8512 FAX: (724) 776-0243TO PLACE A DOCUMENT
3、 ORDER; (724) 776-4970 FAX: (724) 776-0790SAE WEB ADDRESS http:/www.sae.orgCopyright 1970 Society of Automotive Engineers, Inc.All rights reserved. Printed in U.S.A.SURFACEVEHICLE400 Commonwealth Drive, Warrendale, PA 15096-0001STANDARDSubmitted for recognition as an American National StandardJ918cR
4、EV.MAY70Issued 1965-06Revised 1970-05Superseding J918b(R) PASSENGER CAR TIRE PERFORMANCE REQUIREMENTS AND TEST PROCEDURESForewordThis Document has also changed to comply with the new SAE Technical Standards Board Format.1. ScopeThis SAE Standard provides minimum performance requirements and accompan
5、ying uniformlaboratory test procedures for evaluating certain essential characteristics of new tires and newly retreadedtires intended for use on passenger cars.(The requirements published in this SAE Standard pertain to tire sizes currently used on American passengercars and popular sizes used on i
6、mported passenger cars. For related information on tire sizes not listed,contact Society of Automotive Engineers, Inc., Detroit Branch Office, 18121 East Eight Mile Road, EastDetroit, Michigan 48021.)2. References2.1 Applicable PublicationThe following publication forms a part of the specification t
7、o the extent specifiedherein.2.1.1 TRA PUBLICATIONAvailable from 175 Montrose West Avenue, Suite 150, Copley, OH 44321.TRA Yearbook3. Definitions3.1 BeadThat part of the tire which is shaped to fit the rim. Made of high tensile steel wires, wrapped andreinforced by the plies.3.2 Bead SeparationBreak
8、down of the bond between components in the bead area.3.3 Bias Ply TirePneumatic tire in which the ply cords extending to the beads are laid at alternate anglessubstantially less than 90 deg to the centerline of the thread.3.4 CarcassTire structure, excepting tread and sidewall rubber.3.5 ChunkingSep
9、aration of the tread from the carcass in particles which may range from a very small size toseveral square inches in area.SAE J918c Revised MAY70-2-3.6 CordTextile, steel wire strands, and the like, forming the plies in the tire.3.7 Cord SeparationParting of cords from adjacent rubber compounds.3.8
10、GrooveSpace between two adjacent tread ribs or lugs.3.9 Load RangeThe term “Load Range” with a letter (A, B, C, etc.) in tire identification is used to identify a givensize tire with its load and inflation limits when used in a specific type of service, as defined in heading of TRAtables.3.10 Measur
11、ing RimRim of specific width and profile as specified by the Tire does not necessarily represent the actual number of plies in the tire. It isused to relate a given size tire with its load and inflation limits as does load range. Ply rating has been replacedby “load range.” See paragraph 3.9.3.13 Pl
12、y SeparationParting of rubber compound between adjacent plies.3.14 Radial Ply TirePneumatic tire in which the ply cords which extend to the beads are laid substantially 90 degto the centerline of the tread.3.15 Retreaded TireA used tire to which a new tread has been affixed to extend the useful life
13、 of the tire.3.16 RibTread section element circumferentially around tire.3.17 RimMetal support for tire or tire and tube assembly on the wheel.3.18 Section WidthThe linear distance between the exteriors of the sidewalls of an inflated tire at its widest point,excluding elevations due to labeling, de
14、corations or protective bands.3.19 SidewallPortion of tire between tread and bead.3.20 Size FactorThe sum of the tire section width (on the measuring rim) and the outer diameter.3.21 TreadPortion of tire which comes in contact with road.3.22 Tread SeparationTread pulling away from tire carcass.4. Re
15、quirements4.1 StrengthWhen tested in accordance with the procedures described in paragraph 5.1, the average energyabsorbed by the tire at break (or bottoming) shall meet or exceed the requirements established in Tables 1Athrough 1C. In the event that the plunger bottoms against the rim before the ti
16、re breaks at all five points tested,the tire shall be deemed to have passed the test regardless of the energy values. Breaking energy value for atire size not listed in these tables shall not be less than that shown for the nearest smaller size tire of the sameply rating, ply cord material and const
17、ruction.Static breaking energy values for nylon and polyester cord tires are established substantially higher than thosefor rayon cord tires. These differentials are necessary in static test requirements in order to insure comparableimpact resistance under dynamic conditions.SAE J918c Revised MAY70-
18、3-4.2 Tire EnduranceWhen tested in accordance with the procedures described in paragraph 5.2, tires shall showno evidence of tread, ply, cord or bead separation, tread chunking, or broken cord.4.3 High Speed PerformanceWhen tested in accordance with the procedures described in paragraph 5.3, tiressh
19、all show no evidence of tread, ply, cord or bead separation, tread chunking, or broken cord.4.4 Tubeless Tire Resistance to Bead UnseatingWhen tested in accordance with the procedures described inparagraph 5.4, the applied force required to unseat the tire bead at the point of contact shall not be l
20、ess than:1. 1,500 lb for tires with a design section width of less than 6.00 in.2. 2000 lb for tires with a design section width of 6.00 in. or more but less than 8.00 in.3. 2500 lb for tires with a design section width of 8.00 in. or more.Use the section width specified in current TRA Year Book for
21、 applicable tire size designation and type.These tire sizes should be tested on any one of the optional bead seat contours as specified in the current TRAYear Book.4.5 Physical DimensionsUsing the procedure described in paragraph 5.5, all tires shall meet the requirementsof the minimum size factor d
22、imensions listed in the current TRA Year Book.TABLE 1AMINIMUM BREAKING ENERGY VALUES(BIAS PLY TIRES, DESIGN SECTION WIDTH BELOW 6.00 IN. (155 MM.)Cord MaterialLoad Range, in.-lbB(4-Ply Rating)Load Range, in.-lbC(6-Ply Rating)Load Range, in.-lbD(8-Ply Rating)Rayon 1000 1500 2000Nylon or Polyester1600
23、 2400 3200TABLE 1BMINIMUM BREAKING ENERGY VALUES(BIAS PLY TIRES, DESIGN SECTION WIDTH OF 6.00 IN. (155 MM.) AND ABOVE)Cord MaterialLoad Range, in.-lbB(4-Ply Rating)Load Range, in.-lbC(6-Ply Rating)Load Range, in.-lbD(8-Ply Rating)Rayon 1650 2475 3300Nylon or Polyester2600 3900 5200TABLE 1CMINIMUM EN
24、ERGY BREAKING VALUES(RADIAL PLY TIRES)Design Section WidthLoad Range, in-lbB(4-Ply Rating)Load Range, in.-lbC(6-Ply Rating)Load Range, in.-lbD(8-Ply Rating)Below 6.00 in.(155 mm.)1600 2400 32006.00 in. (155 mm.)and Above2600 3900 5200SAE J918c Revised MAY70-4-4.6 Test SampleThree new or newly retrea
25、ded tires are required for each test sample as follows:1. First tire shall be used for physical dimensions, resistance to bead unseating, and strength in thissequence.2. Second tire shall be used for tire endurance.3. Third tire shall be used for high speed performance.5. Test Procedures5.1 Strength
26、5.1.1 PREPARATION OF TIRE FOR STRENGTH TESTThe tire shall be mounted on the rim and shall be conditioned atapproximately the temperature of the room in which the test shall be conducted for at least 3 hr, after whichthe pressure shall be adjusted to the values shown in Table 2. For convenience in te
27、sting, a tube may beused with tubeless tires.5.1.2 EQUIPMENTThe test machine shall be one which can force a cylindrical steel plunger in. in diameter, witha hemispherical end, into the tire at a rate of 2 in./minute.5.1.3 PROCEDUREThe plunger shall be forced into the tread as near to the centerline
28、as possible, avoidingpenetration into a tread groove. Five measurements of force and penetration at break (or bottoming of theplunger against the rim) shall be made at points approximately equally spaced around the circumference ofthe tire.Average energy absorbed shall be calculated from the five en
29、ergy values obtained at break (or bottoming) bymeans of the following formula:(Eq. 1)where: W = energy at break, in.-lbF = force at break (or bottoming), lbP = penetration at break (or bottoming), in.5.2 Endurance Test5.2.1 PREPARATION OF TIRE FOR ENDURANCE TESTThe tire shall be mounted on any rim s
30、pecified in the currentTRA Year Book for the size being tested and inflated to the pressure shown in Table 2. It shall then beconditioned at a temperature of 100 5 F for a minimum of 3 hr. Immediately prior to test, the inflationpressure shall be adjusted to the value specified in Table 2.TABLE 2TES
31、T INFLATION PRESSURESLoad RangeB(4-Ply Rating)Load RangeC(6-Ply Rating)Load RangeD(8-Ply Rating)Maximum Permissible Inflation Pressure (psi)32 36 40Pressure (psi) to be used in tests for physical dimensions, tire strength, tire endurance and bead unseating.24 28 32Pressure (psi) to be used in tests
32、for high speed performance.30 34 38W FP2-=SAE J918c Revised MAY70-5-5.2.2 EQUIPMENTThe test wheel shall be a flat-faced steel wheel, 67.23 in. in diameter, and at least the samewidth as the tread width of the tire to be tested. The tire while being tested shall be located in an air spacecontrolled a
33、t a temperature of 100 5 F. The location for the temperature sensing device to determine theairspace temperature shall conform to the following: 1. For each tire position, the sensor shall be located approximately 6 in. horizontally out from the edge ofthe rim flange at any point in the circumferenc
34、e on either or both sides of the tire or at a point in the testroom where the same temperature readings exist.2. It shall be located away from any wall or ceiling and not in a path where it can be influenced by intakesor outlets, room ventilators, exhaust vents, generators, and so forth.NOTEAlternat
35、e diameter test wheels may be used providing adequate correlation to 62.23 in. test wheel isprovided.5.2.3 PROCEDUREThe tire and wheel assembly shall be mounted on the text axle and pressed against the testwheel with the required axle load: Specifications for the test shall be as shown in Table 3.5.
36、3 High Speed Performance5.3.1 PREPARATION OF TIRE FOR HIGH SPEED TESTThe tire shall be mounted on any rim specified in current TRAYear Book for the size being tested and inflated to the pressure shown in Table 2. It shall then be conditionedat a temperature of 100 5 F for a minimum of 3 hr. Immediat
37、ely prior to test, the inflation pressure shall beadjusted to that specified in Table 2.5.3.2 EQUIPMENTThe test wheel shall be a flat-faced steel wheel 67.23 in. in diameter and at least the samewidth as the tread width of the tire to be tested. The tire, while being tested, shall be located in an a
38、ir spacecontrolled at a temperature of 100 5 F.The location for the temperature sensing device to determine the airspace temperature shall conform to thefollowing:1. For each tire position, the sensor shall be located approximately 6 in. out from the edge of the rimflange at any point in the circumf
39、erence on either or both sides of the tire or at a point in the test roomwhere the same temperature readings exist.2. It shall be located away from any wall or ceiling and not in a path where it can be influenced by intakesor outlets, room ventilators, exhaust vents, generators, and so forth.NOTEAlt
40、ernate diameter test wheels may be used providing adequate correlation to 67.23 in. test wheel isprovided.TABLE 3TIRE ENDURANCE TEST(1)1. The test will be conducted without adjustment of inflation pressure or other interruption. This per-mits normal pressure buildup.Speed, m.p.h.Inflation Pressure,
41、psiLoad RangeB(4-PR)Inflation Pressure, psiLoad RangeC(6-PR)Inflation Pressure, psiLoad RangeD(8-PR)Test LoadSee Table 5(Col. No.) Hrs.Total Miles50 24 28 32 1 4 50 2 6 50 3 24 1700SAE J918c Revised MAY70-6-5.3.3 PROCEDUREThe tire and wheel assembly shall be mounted on the test axle and pressed agai
42、nst the testwheel with the required axle load. Specifications for the progressive test speeds and conditions shall be asshown in Table 4.After 2 hr breakin running at 50 mph, the tire shall be cooled to an equilibrium temperature of 100 5 F.Inflation pressure shall then be readjusted to initial pres
43、sure and test continued without further adjustment ininflation pressure. This permits normal pressure buildup.After cooling period resume test at 75 mph. Increase speed 5 mph every hr until maximum indicatedspeed has been achieved. Standard highway tires shall be tested at speed up to and including
44、85 mphrequirement. Deep tread winter tires shall be tested at speeds up to and including the 80 mph requirement.5.4 Tubeless Tire Resistance to Bead Unseating5.4.1 PREPARATION OF TIRE-WHEEL ASSEMBLY FOR BEAD UNSEATING TESTThe tire shall be washed and dried atthe two beads, mounted on a clean and pai
45、nted rim without the use of lubrication, and inflated to theapplicable pressure, Table 2, at ambient temperature.5.4.2 EQUIPMENTA fixture used to support the mounted tire-wheel assembly is shown in Figure 1. A standardblock, detailed in Figure 2, is forced against the tire side wall as dictated by t
46、he fixture geometry, at a point onthe side wall as indicated by distance “A” in Figure 1. This load may be applied by a hydraulic ram or itsequivalent.TABLE 4HIGH SPEED PERFORMANCESpeed,mphInflation Pressure, psiLoad RangeB(4-PR)Inflation Pressure, psiLoad RangeC(6-PR)Inflation Pressure, psiLoad Ran
47、geD(8-PR)Test LoadSee Table 5(Col. No.) Hrs.TotalMiles50 30 34 38 1 2 75 30 34 38 1 1/2 80 1 1/2 85 1 1/2 220TABLE 5TEST LOADS(1)1. Use loads for indicated pressures as found in current TRA Year Book for the particular tire size and load range.Load RangepsiCol. 1psiCol. 2psiCol. 3B(4-ply rating)24 2
48、8 32C(6-ply rating)28 32 36D(8-ply rating)32 36 40SAE J918c Revised MAY70-7-FIGURE 1BEAD UNSEATING TEST FIXTUREFIGURE 2BLOCK DIAGRAMSAE J918c Revised MAY70-8-5.4.3 PROCEDUREWith the tire and wheel mounted in the fixture, the load shall be applied through the block tothe tire sidewall at a rate of 2
49、in./minute with the load arm substantially parallel to the tire and rim assembly atthe time of engagement. Increase the load until the bead unseats or until the applicable loads as specified inparagraph 4.4 are met. Repeat the test for at least four equally spaced points round the tire.5.5 Physical DimensionsThe size factor of a tire is the sum of the tire section width (on its measuring rim) andthe outer diameter. Determination of tire section width is to be done with the tire
