BS AU 50-2-7:1987 pdf free download.Tyres and wheels.
7.1 Scope
This Section of BS AU 50: Part 2 gives recommendations for vehicle manufacturers on the initial steps to be taken in selecting wheels for commercial vehicles and recornmendations on the cue of wheels for the user. Descriptions of the principal types of wheels and attachments, the sequence
of attachment stud tiitening and the checking procedures to be carried out when fitting wheels to vehicles are also given.
NOTE 1. Appendix A gives the principal types of rims and wheels used in the UK. For further details see 85 AU 50: Pert 2:
Sections 0, 1 and 2.
NOTE 2. The titles of the publications referred to In this standard are listed on the inside back cover.
72 Tyre and nm selection
When selecting a tyre and rim for a vehicle it is important to ensure that the correct choice is made. The initial choice is the tyre. Basic factors which influence this choice are:
(a) load carrying capacity;
(b) conditions of service and operational use.
The basic tyre choice is between tube type or tubeless tyres and between diagonal or radial tyres.
The complete tyre specification, including the rim profile. should be agreed between the tyre, wheel and vehicle manufacturers.
NOTE. lnformat.on on tyre sizes, inflation pressures and axle Ioch is given in BS AU 50 Part 1: Section 2. Rim data are wen in BS AU 50: Pare 2: Sections 0 and 1.
7.3 Wheel selection
It is important that the selection of the type of wheel should be by agreement between the vehicle manufacturer and the wheel and tyre manufacturers.
Factors affecting wheel selection are:
(a) compatibility with the vehicle type, design and performance requirements;
(b) compatibility with the vehicle for installation, i.e. ensuring the correct wheel to hub attachment. and the type of stud and nut fixing. Also that the wheel has adequate clearance eround the vehicle brake and hub, the steering mechanism and the body parts;
(c) compatibility with the tyre for rim profile, valve fitment, offset and, where required, for dual (twin) type assembly, that the wheel has the correct half dual spacing (offset) for the selected tyre size.
resulting in stretched threads, broken studs and cracked wheels.
Following a wheel fitting the nuts should be rechecked for tightness, by hand, using the recommended torque wrench and torque values, after the vehicle has travelled approximately 50 km (or the distance recommended by the vehicle manufacturer). Nuts should also be checked for tightness at the normal service intervals.
7.9 In-service wheel checks
During normal vehicle use the wheels should be examined regularly for signs of looseness. Looseness is usually seen by rust marks around the stud holes and by signs of fretting. In addition the wheels should be examined for cracks and distortion. If cracks are found the tyre should be deflated by removing the valve core before removing the wheel from the vehicle (in the case of dual tyres both tyres should be deflated). It is essential that cracked wheels or wheels with deformed bolt holes should be removed and scrapped. Damaged wheels should not be repaired for reuse.
7.10 Removing wheel from vehicle
Before commencing removal of the wheel from a vehicle, the tyre and the wheel should be carefully examined for defects and damage. (For further details see the publications referred to in 7.5.)
In the event of difficulty in removing a wheel from a hub or drum, under no circumstances should direct hammer blows be made to the wheel rim. A protective block of wood or a rubber faced mallet should be used with caution. With divided type wheels it is essential that the outer clamping nuts should not be loosened or unscrewed. These are coloured as follows:
red for wheels painted in colours other than red yellow for wheels painted red.
Before removing divided wheels from the vehicle the tyres should be deflated by removing the valve core.
If there are signs that a tyre has run substantially deflated, or has stood in a deflated condition, wheel components may have become damaged or displaced. In which case the assembly should be removed from the vehicle and stripped and each part should be examined and corrected/treated before being reassembled.
(a) (I) Do contact the vehicle manufacturer for wheel specit ications and recommendations.
(b) (1) Do check the condition of wheels regularly. Do derust and repaint wheels.
(c) (I) Do replace damaged components (loose flanges and/or lock rings).
(d) Ci) Do follow fitting instructions and ensure there is the correct gap between the ends of two-piece spring flanges and lock ring of three/four-piece rims.
(e) Ci) Do discard and scrap damaged components and wheels.
Do check the condition of the wheel fixing attaching the wheel to the vehicle hub.
(f) C.) Do ensure, where nut seat type fixing is used. that the conical nut and stud are used with the conical stud hole in the wheel and that the spherical nut and stud are used with the spherical stud hole in the wheel.
Do use the correct flat faced captive washered nuts on spigot mounted wheels.
Ci) Do ensure that nuts run freely on stud threads.
Ci) Do ensure that nut seats are not damaged.
(I) Do check that studs are correctly seated in hub.
Ci) Ci) Do follow the procedures for the correct assembly of wheel to hub and the nut
tightening sequence.
(k) (i) Do tighten the nuts with a tool applying the torque value recommended by the vehicle manufacturer.
Do recheck the nuts for tightness after the vehicle has travelled a short distance and at the normal servicing intervals.
(1) Ci) Do deflate the ryre before removing a defective wheel from the vehicle.
Do deflate both tyres in the case of twin (dual) assemblies.
(m) (i) Do deflate the tyre, by removing the valve core, before removing a divided type wheel.
Cn) Ci) Do inflate the tyre with dry air.
(ii) Do not assume that the rim profile size indicates suitability of wheel use.
(ii) Do not use excessively corroded or pitted components or wheels.
Do not reassemble when paint is wet.
Do not allow other than minimal thickness of paint on wheel surfaces.
(ii) Do not interchange or mix different sizes and types of components.
Do not interchange or mix different manufacturer’s products.
(ii) Do not damage wheel or parts by bad fitting or use of incorrect fittings, tools and levers.
(ii) Do not weld or repair damaged wheels or stud holes or components, or replace the centre of disc wheels.
(ii) Do not fit conical collars and conical nuts to wheels with spherical holes.
Do not fit spherical collars and spherical nuts to wheels with conical holes.
Do not fit other than flat faced captive washered nuts to spigot mounted wheels.
(ii) Do not use grease on stud threads.
(ii) Do not use wheels with worn nut seats.
(ii) Do not assemble wheels on stretched, damaged or worn studs and washers.
(ii) Do not fully tighten one nut while the others are still loose.
(ii) Do not overtighten the nuts by using extensions on wheel nut spanners and spiders.
Do not use air impact tools for the final nut tightening.
(ii) Do not reuse a tyre/wheel assembly that has run substantially deflated or stood in a deflated condition, until a complete examination and reassembly in accordance with the appropriate procedures has been made.
(ii) Do not undo the clamping bolts of divided type wheels until the tyre has been completely deflated.
(ii) Do not inflate the tyre with moist or contaminated air.