Kimberley KARAVAN 2021

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creates a preload, which is what

serves to clamp the wheel securely

to the hub. If undertightened, the

nut (or bolt) can gradually loosen,

and we all know the consequences

of that. If overtightened, the stud or

bolt can exceed its “elastic” range,

and can permanently stretch

(fatigue), which destroys its ability

to provide clamping load. If this

happens, the stud or bolt can either

loosen on its own or can break dur-

ing operation. Especially when deal-

ing with today’s lightweight alloy

wheels and sometimes light (and

thin) rotor mounting faces, severe

wheel vibrations under braking can

occur if wheels are improperly or

unevenly tightened.

REASONS TO NOT USE

AN IMPACT GUN ON

ALLOY WHEELS

An impact gun (especially when

installing wheels) can wreak havoc

on alloy wheels. Fastener damage

can occur as a result of a socket

banging against a nut’s c

hrome plat-

ing. If aftermarket spline-drive

“tuner” nuts are used, the narrow

splines can be burred. Probably the

biggest area of concern is inaccurate

and/or excessive clamping loads,

which can distort the wheel and its

mated hub/rotor, leading to vibra-

tion complaints. Additional wheel

cosmetic damage can result if sock-

et-to-fastener recess is minimal, or

if a thick-walled socket is used that

minimizes clearance, the outer wall

of the socket can abrade against the

wheel’s nut recess.

If the socket is dirty, abrasive

damage to both the fastener and

wheel are possible. In addition,

excessive tightening can cause the

nut or bolt seat to pound into the

aluminum wheel’s seat pocket,

displacing the aluminum (goug-

ing/deforming the alloy). This can

lead to eventual

fastener loosening,

since the seat base integrity has

been deformed

or reduced.

Excessive tightening can also stress

the wheel stud, permanently

stretching the threaded shank

INSTALLING ALLOY WHEELS

While the use of a torque wrench is preferred for tightening an alloy

wheel, if an impact gun must be used, be sure to employ torque

sticks, which feature a pre-set torsional limiting range to prevent

over-tightening.

Any busy shop should have their torque wrenches periodically re-

calibrated in order to maintain accuracy and consistency.

beyond its elastic point, weakening

the stud considerably. When this

happens, the stud may eventually

break or allow the nut to loosen.

WHEEL FASTENER

TORQUE VALUES

Always refer to the Toyota tighten-

ing specifications for proper wheel

fastener torque values. Listed here is

a broad generalization of torque

values, based on fastener size, for

example only.

TORQUE WRENCHES

PREFERRED

While the use of a calibrated

torque wrench is always preferred

for wheel fastener tightening, an

option (if your shop decides that it

simply must use an air gun)

involves the use of “torque sticks,”

which are available individually or

in sets.

Each tool is essentially a short tor-

sion bar with a 1/2-inch drive at one

end and a hex socket at the other

end. Using this tool on the air gun

allows

you to pneumatically tighten

the wheel fastener to within a theo-

retically acceptable range. Each

“stick” is color coded and labeled in

terms of its hex size and its torque

range.When the stick is subjected

to its pre-set torque range, the cen-

ter section of the tool begins to

twist (similar to a torsion bar

spring), theoretically preventing

tightening the fastener beyond that

pre-set range. If you can’t convince

your shop to take the time to use a

torque wrench, at the very least be

sure to use a torque stick.

CHECK WHEEL

CENTERING

Wheels are designed to center onto

the vehicle hubs by one of two meth-

ods: lug-centricity or hub-centricity.

A lug-centric wheel relies on cen-

tering via the fastener locations

only. As the lug nuts (or wheel bolts)

are tightened, the wheel is centered

onto the hub,

guided by the wheel

studs and the seating of the wheel

nuts. This requires precise location

of both wheel bolt holes and the fas-

tener locations on the hub.

A hub-centric wheel is centered

onto the hub via the fit of the wheel

center hole at the hub face. The hub

face will feature a center lip that

engages into a recess on the wheel’s

hub face. Hub-centric designs more

precisely locate the wheel onto the

hub, to minimize the chance for

installed-radial-runout.All later-

model Toyota wheels and hubs are

designed for hub-centric fitments.

However, some earlier Toyotas (1989

and older) may feature lug-centric

designs, wherein the wheel is cen-

tered onto the hub as the wheel nuts

are tightened.

It’s important to recognize which

type of centering you have. I

f the

hub design calls for a hub-centric

T OYOTA ’S S UPPORT T O A UTOMOTIVE R EPAIR

INSTALLING ALLOY WHEELS

If the customer brings in aftermarket wheels, pay attention to the

hubcentric fit of the wheel’s center hole to the hub’s center flange

lip. Since the vast majority of Toyota vehicles use a hubcentric fit,

make sure that the wheel closely centers itself at the hub. Some

aftermarket wheels may be made to fit a variety of vehicles, in which

case the wheel’s center hole may be larger than is required for prop-

er fit. In these cases, hubcentric adapter rings will be needed. Here a

hubcentric ring is installed onto an aftermarket wheel. The inside

diameter of this ring will match the required size for the customer’s

Toyota vehicle.

Vehicle

RAV4

MR2

Avalon

Camry

Solara

Celica

Echo

Scion tC

Prius

Sienna

Highlander

Scion xB

Scion xA

Corolla

Matrix

4Runner

Tacoma

Tundra

Sequioa

Land Cruiser

Torque

76 ft-lbs (103N-m)

83 ft-lbs (110 N-m)

97 ft-lbs (131 N-m)

Kimberley KARAVAN 2021 - Page 109