MAINTENANCE, INSPECTION AND TESTS 3. PRELIMINARY INSPECTION A. VISUAL INSPECTION I. Visually inspect the tyre and replace the same if any of the following defects are found: Bumps or bulges in the tread or the side of the • tyre. Cuts, splits or cracks. • Excessive tread wear or non-uniform tyre wear. • Remove tyres for replacement preferably when remaining tread depth in any part of tyre tread reaches 1.6mm. Misalignment of wheels and axles in front or rear, improperly operating brakes or shock absorbers, bent wheels, worn bushings and other mechanical problems can cause uneven wear. Hence such defects should be immediately corrected. Tyre wear can also be due to faulty steering or suspension components, Incorrect Steering geometry adjustments and also worn out wheel bearing. Hence all these components should be inspected before arriving at the cause for tyre wear. Refer their respective groups for procedure to inspect the components. PRECAUTIONS II. Do not stand over the tyre while inflating. Bead • may break when it snaps over rim’s safety hump and cause serious personal injury. Do not exceed specified pressure when • inflating. If specified pressure will not seat beads, deflate, re-lubricate and re-inflate. While removing tyre from wheel rim and • mounting it back on wheel rim, take precaution not to damage tyre bead. Use tyre removal and assembly machines. Damage or cut on tyre bead may cause gradual loss of air deflation of tyre. If wheel rims get damaged in the service, get • wheel rims repaired/replaced immediately. Running vehicle with damage rim may cause deflation of tyre and subsequent dislodging of tyre from rim. Maintain recommended inflation pressure in • tyre. Over inflation in particular, may cause puncture or bursting of tyre. Avoid unequal load distribution on wheels • which may be due to A difference in the overall diameter of the a. two tyres. The difference in the amount of air pressure b. in each tyre. The contour of the roads. c. Axle sag. d. FOLLOWING PRECAUTIONS SHOULD BE TAKEN WHILE 1. Installing wheel assembly on wheel hub The wheel must be correctly positioned a. relative to the hub when mounting on the vehicle. To prevent rusting, small amounts of oil b. may be applied to the wheel bolts and nuts. Care must be taken not to over lubricate. Wheel bolts and nuts should be tightened c. as per specified torque value. 2. Removing wheel assembly using a hydraulic jack. Follow the jacking instructions. a. Make sure to set the jack properly in the b. jack point. Raising the vehicle with improperly positioned jack may damage the vehicle or causes the personal injury. Do not carry any other work or never get c. under the vehicle supported by jack as it may cause personal injury. Do not start or run the vehicle while d. supported by jack. Do not lift the vehicle with any anyone e. seated in the vehicle. Do not lift the vehicle excessively. Lift up to f. sufficient height necessary to remove and change the wheel. REGULAR MAINTENANCE B. INFLATION I. Check tyre pressures when tyres are cold. • Check the tyre pressure & condition after every • 15 days including spare wheel. NOTE Excessive bolt tightening may cause deformation of bolt causing failure and an insufficient tightening may cause the wheel loosening. WHEELS AND TYRES 11
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