COST 334

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4. On Maximum Designed Operating Tyre Inflation PressureIn addition to the proposed limits on TCF value of the tyre, it is also recommended thata maximum limit be placed on the manufacturer-recommended inflation pressure ofthe tyre (measured cold) according to the allowable load level of the specific axle onwhich the tyre is mounted. This will ensure that the TCF limits cannot be inadvertentlyexceeded by the use of increased inflation pressure.The proposed maximum designed operating tyre inflation pressure (measured cold) is9 bars.Much progress has been made in recent years on the development of on-board systemsfor the measurement and control of tyre inflation pressures. It is further recommended,therefore, that consideration is given to introducing legislation requiring the use ofsuch systems on the largest (5 and 6-axle) vehicles, in order to ensure compliance withtyre manufacturer's recommended inflation pressures for given loads and duty cycles.This will produce benefits to operators in terms of improved tyre performance (tyrewear and rolling resistance), and to society in terms of minimised pavement wear andreduced safety risks.5. On future research on the Tyre Configuration FactorThe work of Task Group 3 has been necessarily limited to a proportion of thecombinations of tyre type, pavement type, and pavement distress modes that need tobe considered. Among a number of other issues, it is recommended that furtherresearch is carried out, as a priority, on:156• The effects of different tyre load configurations on concrete pavements, bridges,viaducts, etc. It is anticipated that the influences of tyre type will be stronglydependent on the materials and structural designs used. Further research isnecessary to expand the present work to other types of structure.• The separation of the effects on thin and medium pavements of different tyre loadconfigurations.• Comparative testing of actual pavement performance in respect of fatigue andsecondary rutting, to validate the present predictions based on pavement responseinstead of performance.• The effects of tyre dynamics with different types and sizes of tyres, on pavementsof differing thicknesses.• The refinement and expansion of the TCF formulae developed by TG3.6. On future development of truck tyresThe results of the work provide useful guidance to tyre manufacturers on how tyresmight be developed to limit pavement distress. Tyre manufacturers are not onlyconcerned with this issue, of course. TG3 acknowledges that the properties of a giventyre size, including its contact area, are the results of an equilibrium between manyperformances including adherences (dry, wet, snow, ice …), noise, fuel consumption,treadwear, vehicle handling. All these factors have to be taken into account.• Nevertheless, from the point of view of pavement distress alone, it is recommendedthat future truck tyres are developed with limited TCF values. This can be achievedin particular by providing sufficient width and length of the tyre-pavementfootprint area.version 29 November 2001
Chapter 4• From the same viewpoint it is recommended that the existing 385/65R22.5 tyresize be modified to achieve lower TCF values. This can be done by providing agreater width of the tyre footprint area.version 29 November 2001157
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European Co-operation in the Field
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Table of ContentsTable of ContentsE
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Chapter 4Chapter 4 : Pavement Wear
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Chapter 44.2 SCOPE OF THE WORKHisto
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Chapter 44.3 DEFINITION OF THE PROB
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Chapter 4It is observed 50 that the
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Chapter 4RimTyresFigure 4.4 - Tyre
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Chapter 4• Trucks may travel incr
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Chapter 4Table 4.2 - Length of Prim
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Chapter 4be noted that not all coun
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Chapter 4lesser effect than the loa
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Chapter 4(side view)1. load scaleor
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Chapter 44.3.4.4 The contact area s
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Chapter 4Figure 4.10 shows a simpli
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Chapter 4others). These different g
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Chapter 44.3.5.2 Pavement distress
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Chapter 44.3.6 Load effects4.3.6.1
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Chapter 4arrives within that period
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Chapter 4inflationdifferencepressur
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Chapter 4Mechanistic-empirical perf
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Chapter 4distressN2N1D1D2load cycle
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Chapter 4pressure, diameter, contac
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Chapter 4Table 4.10 - Summary of re
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Chapter 4Table 4.11 - Properties of
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Chapter 4difference in tyre pressur
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Chapter 4Table 4.14 - Footprint wid
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Chapter 4• Drive axle, twin tyres
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Chapter 4for a given rim diameter,
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Chapter 4Figure 4.21- Setup for whe
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Chapter 4Table 4.17 - Unequal load
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Chapter 44.4.9.3 Tekscan Measuremen
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Chapter 4Figure 4.30 - 295/60R22.5
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Chapter 4The following conclusions
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Chapter 4An extensive identificatio
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Chapter 4different diameter tyres.
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Chapter 4pavement surface, for the
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Chapter 4Table 4.21 - Maximum subgr
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Chapter 44.50Initial readings amend
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Chapter 42.0m 3.5m 2.0m 2.0m 3.5m2.
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Chapter 4• the maximum rut depth
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Chapter 4measurements but needs fur
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Chapter 4Figure 4.47 - Manège de F
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Chapter 4(0.48 m depth) and near th
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Chapter 4this question was to compa
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Chapter 4The conclusion of the anal
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Chapter 46050Stress [kPa]403020100B
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Chapter 4Length contact areaDirecti
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Chapter 44.5.9.2 Numerical modelTab
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Chapter 4Table 4.33 - Practical per
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Chapter 4Practical permanent deform
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Chapter 4• “Pressure ratio” i
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Chapter 4also may be that the param
Page 105 and 106: Chapter 41.21.0Ln Distress ratio pr
Page 107 and 108: Chapter 44.5.10.7 Regression result
Page 109 and 110: Chapter 44.5.10.8 Summary and concl
Page 111 and 112: Chapter 44.6 EFFECTS OF UNEQUAL LOA
Page 113 and 114: Chapter 4• Molzer used worst-case
Page 115 and 116: Chapter 4Table 4.43 - Vertical subg
Page 117 and 118: Chapter 4Table 4.47 - Practical per
Page 119 and 120: Chapter 42544 km (divided over 1998
Page 121 and 122: Chapter 44.7 EFFECTS OF DYNAMICS4.7
Page 123 and 124: Chapter 43. Measurements of dynamic
Page 125 and 126: Chapter 4Figure 4.65 - Truck tyre o
Page 127 and 128: Chapter 4road. The results of the D
Page 129 and 130: Chapter 4Table 4.55 - Calculated st
Page 131 and 132: Chapter 4The wide base single tyre
Page 133 and 134: Chapter 4In the two tables below th
Page 135 and 136: Chapter 44.8.3 Evaluation and sensi
Page 137 and 138: Chapter 4fatigue• The total conta
Page 139 and 140: Chapter 4Like for the towed axles,
Page 141 and 142: Chapter 4Table 4.66 - Overview of a
Page 143 and 144: Chapter 44.8.6 Specification of roa
Page 145 and 146: Chapter 4Table 4.67 Values of Axle
Page 147 and 148: Chapter 4Table 4.70 Proposed TCF li
Page 149 and 150: Chapter 44.9 SUMMARY, CONCLUSIONS A
Page 151 and 152: Chapter 4values were calculated as
Page 153 and 154: Chapter 4334 established good techn
Page 155: Chapter 4The development of the Tyr
Page 159 and 160: Chapter 4DBMdistressDLCdouble axled
Page 161 and 162: Chapter 4pavementPCCperformanceperm
Page 163 and 164: Chapter 4tandem axleTCFtfthermal cr
Page 165 and 166: Chapter 44.11 REFERENCESAddis RR (1
Page 167 and 168: Chapter 4rutting from new single ty
Page 169 and 170: Chapter 4Molzer C (1998) Revision o
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COST 334

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