may include:
0
0
Loose or worn wheel bearings.
Loose or worn suspensions or steering components.
0 Worn or damaged drive shaft slip yoke joint.
0 Front disc rotor runout.
o Loose engine or transmission supports.
0 Driveline alignment.
0 Engine driven accessories.
Suspension Systems
11.4 DIAGNOSIS AND TESTING
' 11.4.1 Tire Wear
Tires should be inspected as abnormal or excessive wear may becaused by incorrect wheel alignment, wheelbire im- balance, or incorrect tire pressure.
1 1.4.2 vibration and Roughness
Vibration, roughness, and shimmy conditions may be caused by excessive tire or wheel runout, worn or cupped tires,
or wheel and tire unbalance.
Most of these conditions are due to irregularities in the road surface, hence driving the vehicle on different types of
road surface will often indicate the cause of the condition.
Do not automatically suspect the tires when attempting to diagnose a vibration concern as other sources of vibration
Before investigating any other vibration concerns,
a roaG &est and a customer inter\,.dw (if possible) should be carried
out. This can provide much of the information needed to find the source of vibration.
Drive the vehicle on a road that is preferably smooth and free of undulation and
if vibration is apparent note, the speed at which thevibration occurs, whattype of vibration occurs in each speed range (mechanical or audible), howthevibra- tion is affected by changes in vehicle speed , engine speed and engine torque, and the type of vibration sensitivity
(torque sensitive, vehicle speed sensitive, or speed sensitive).
Some of the condition terms used when describing sources of vibration are explained as follows:
0 Torque Sensitive
This condition can be improved or worsened by accelerating, decelerating, coasting, maintaining
a steady
vehicle speed and application of engine torque.
0 Vehicle Speed Sensitive
This means that the vibration always occurs at the same vehicle speed and is not affected by engine torque,
engine rpm, or transmission gear selection.
B
0 Engine Speed Sensitive
This means that the vibration occurs
at varying vehicle speeds when a different transmission gear is selected.
It can sometimes be isolated by increasing or decreasing engine speed with the transmission in 'NEUTRAL', or
by stall testing with the engine in gear. If the condition is enginesensitive, the condition is not related to tires.
If the road tests indicates that the vibration is related to the tires or wheels,use a 'lire Wear Diagnosis Chart' to
investigate the cause of concern. Should the road test indicate that there is tire whine, but noshake or vibration,
the noise originates from the contact between the tire and the road surface.
X300 VSM 3 Issue 1 August 1994
Tire Replacement And Wheel hterchanging
WARNING: UNDER NO CIRCUMSTANCES SHOULD CROSS-PLY TIRES BE FITTED.
When renewal of tires is necessary, it is preferable to fit a complete set.
Should eitherfront or reartires only (i.e.
notthe full set) show a necessityfor renewal, newtires must befitted to replace
the worn ones.
No attempt must be made to interchange tires from the front to the rear orvice-versa, as wear produces a characteristic
pattern on each tire depending upon its position on the vehicle. If this position is changed after wear has occurred, the
performance of the tire will be adversely affected.
It should be remembered that new tires must be balanced.
The radial ply tires specified here are designed to meet the high speed performance of this vehicle. Only tires of ident
- ical specification as shown in this section must be fitted as replacements. If two replacement tires are fitted to one axle,
they must be of the same type and pattern as those on the other axle, i.e. tires must be used in sets of four of the same
manufacturer and tread pattern,
not intermixed.
Tire Fitments
32 Liter 4.0 Liier 4.0 Liter SC 6.0 Liter 6.0 Liter 0
(Normally (Daimler & (UK, Euro, ROW
Aspirated) Federal
XJ12) XJ12)
Standard 225 160 ZR16 225 I60 ZR16 - 225 I60 ZR16
225
1 55 ZR16 225 I55 ZR16 - - 225 I55
ZR16
- 255 I45 ZR17 - -
Space saver 115/85R18 115/85R18 115185 115185 115185
(where fitted) RI8 R18 RI8
Recommended tires
The following tires are recommended:
225 I60 ZR 16 ...................................................... Pirelli P4000 E
225 155 ZR 16 ...................................................... Pirelli P6000
225 155 ZR 16 ...................................................... Dunlop SP Sport 2000
255
145 ZR 17 ...................................................... Pirelli P Zero
115185 R 18 Pirelli .......................................................
0
Recommended Winter (Snow) Tires
Tire designation:
225 I60 R 16 ...................................................... Goodyear Eagle GW M+S
225 155 R 16 ....................................................... Pirelli Winter 210 M+S
225 I55 R 16 ...................................................... Michelin 330 M+S
Only use winter tires in complete sets of the same type I size.
CAUTION: Tire directional indicators must rotate in a clockwise direction when viewed from the right-hand side of
the vehicle, and in an anti-clockwise direction when viewed from the left-hand side.
The recommended pressures for winter tires are shown in the table of inflation pressures on the following page.
0
X300 VSM Issue 1 August 1994 AI-95MY 10
