TIAGO

SUSPENSION

5.10 WHEELS AND TYRES

Wheels and tyres assembly is an important part in

the vehicle; it has effect on performance of the

vehicle.

It is responsible to transfer the required road feel to

the driver and passengers. Hence it is required to

follow correct workshop practices.

A) TYRE INSPECTION

Inspect the tyre for the following and replace if

found.

a) Bulge on threads and side walls.

b) Cuts, cracks, abnormal, excessive, and Un-

uniform tyre wear.

B) REPLACEMENT OF TYRES:

When replacement is necessary, the original

equipment type tyre should be used. Replacement

tyres should be of the same size, load range,

speed rating, manufacturer and construction as

those originally on the vehicle. Use of any other

size or type tyre may affect ride, handling,

speedometer/ odometer calibration, vehicle ground

clearance and tyre clearance to the body chassis.

It is recommended that new tyres be installed in

pairs on the same axle. If necessary to replace only

one tyre, it should be paired with the tyre having

the most tread, to equalize braking traction. Also

do not mix different types of tyres (viz. radial, bias

etc) on the same vehicle, because it badly affects

the handling of the vehicle.

C) REPLACEMENT OF WHEELS:

Wheels must be replaced if

1. They are bent,

2. Dented,

3. Have excessive lateral or radial run out,

4. Air leak through welds,

5. Have elongated bolt holes,

6. If wheel bolts will not stay tight, or

7. If they are heavily rusted

8. Chip off (for Alloy wheel).

Wheels with greater run out than specification may

cause vibrations.

Replacement wheels must be equivalent to the

original equipment wheels in load capacity,

diameter, and rim with offset and mounting

configuration. A wheel of improper

Size or type may affect wheel and bearing life,

brake cooling, speedometer/odometer calibration,

vehicle ground clearance, and tyre clearance to

body and chassis.

5.10.1 HOW TO MEASURE WHEEL RUNOUT:

To measure wheel run out, it is necessary to use

an accurate dial indicator. The tyre may be on or

off the wheel. The wheel should be installed on a

wheel balancer for proper measurement.

Take measurements of both lateral run out and

radial run out at both inside and outside of the rim

flange. With the dial indicator set in place securely,

turn the wheel on full revolution slowly and record

every reading of the indicator. See fig 86.

When the measured run out exceeds the

specification and correction by the balancer

adjustment is impossible, replace the wheel. If the

reading is affected by welding, paint or scratch, it

should be ignored.

Radial

Run out limit

Lateral

Run out limit

Steel wheel

/alloy wheel

1.0 mm

(0.039 in)

1.2 mm

(0.047 in)

FIG. 86

MATCHED TYRES AND WHEELS:

Tyres and wheels are match mounted at the

assembly plant. This means that the radially stiffest

part of the tyre or “high spot” marked in RED on

tyre is matched to the smallest radius or “low spot”

of the steel wheel rim. In case of alloy rims valve is

to be matched with YELLOW spot on the tyre. The

YELLOW spot is an indication of low point of static

imbalance of tyres. This is done to provide the

smoothest possible ride. The color spots on the

tyres are originally marked by paint dot on the out

board sidewall. This paint dot will eventually get

wash off the tyre.