Wheel and tyres

1 Wheels
A disk or spoke with hub (revolving around axle) at a center and has a rim around the outside of disc for
mounting the tyre.

1.1 Necessity of Wheels

• Wheel must sustain vehicle and passenger load
• Must provide cushioning effect and cope’s with steering control

1.2 Requirement of Wheels

• Should be light in weight
• Should be possible to remove or mount the wheel easily
• Must be balanced both statically and dynamically
• Wheels material should not deteriorate
• Must have better corrosion resistance
• Should have good load carrying capacity
• Should resist bending, tensile, compressive and torsional resistance
• Must provide cushioning effect to absorb shock load due to road irregularities

1.3 Valve Stems and Cores

Functions – Retains air, allows inflation and deflation.

• Rubber stem of the valve is pulled into the wheel.

• Valve core contains a spring-loaded air valve insert.
• The valve core also has a sealing washer and a seat washer.
• Valve cap keeps out dust and helps keep air in.
• Valve caps Sealing washer Seat washer Valve stem Valve core Tyre pressures must only be checked
and adjusted when the tyre is cold

1.4 Types of wheels

• Pressed steel disc wheel
• Wire wheel
• Light alloy cast or forged wheel
1.4.1 Pressed steel disc wheel
• This wheel is used over 90 % of world manufacturers worldwide because of its simplicity, robust
construction, low cost manufacture, mostly used in heavy vehicles.
• This type consists of two parts, a steel rim to accommodate the tyre and a pressed steel disc.
• The rim and disc may integral or permanently attached.
• The rim profile (tyre bead profile) indicated by letters J, K, JJ, JK or B in the specification.
• WELL is used for removing and mounting the tyre easily.
• Rim seat has 5 to 15-degree taper so that as the tyre is inflated, the beads are forced up taper to give
wedge fit and makes a good seal.

• The Steel disc performs the function of the spokes.

• Holes are provided in the disc for ventilation and cooling of brake drum.
• A hole in the rim is used to accommodate the tube valve.
Application: Used in heavy motor vehicles and cars.

1.4.2 Wire wheel

• it is the earliest type of wheel but it’s use is limited to vintage sports, racing cars and two wheelers.
• It is lighter, better heat dissipation for brake drum and can be fitted and removed easily as only one
nut has to be removed.
• The spokes are attached to the rim on one end and pushed through a hole in the wheel rim on the
other end.
• Spokes are screwed down by nipple, pulling the spoke tightly.
• Spokes are mounted in criss-cross manner.
• The spokes carry the weight, transmit the driving and braking torque and withstand side forces while
cornering, but it can’t take compressive or bending stress.
• As rim has a hole, tubeless tires can’t fit into these wheels.

➢ Components: Spokes, Hub, Rim

Spokes:

• One end of spokes is hooked to hub while another end is attached to wheel rim
• Spokes carries vehicle’s and passenger weight.
• Transmits driving and braking torque and withstand side force while cornering.

Hub

• Hub is provided with internal splines and is mounted on axle shaft.

• One end of spoke is hooked to hub end

Rim

• Rim has holes at the Centre for attaching spokes.

• The only disadvantage of this rim is, tubeless tire cannot be mounted on it because of holes of
the rim.

Advantages

• Light in weight
• Provide better cooling of brake drum
• High strength
• Better changeability as only one nut needs to be opened for mounting and dismounting of
wheels.

1.4.3 Light alloy cast or forged wheel

• This is the most recent type automobile wheels in use, especially in cars and two wheelers.
• It is made of aluminium or magnesium alloys.
• It weighs about 50% of the steel wheel for the same strength and also alloys are best heat conductors
which helps the heat dissipation.
• Magnesium alloys have high impact and fatigue strength so that they can stand vibrations and shock.
• Generally aluminium alloy wheels are used for cars and commercial vehicles while magnesium
alloy wheels are used by sports cars.
• It has low aspect ratio which gives stability on cornering.
Advantages

• Better conductor of heat, which helps to dissipate heat generated by braking.

• Wider rims are possible in this wheel which improves stability on cornering.
• Cast or forged wheel needs to be machined yet it helps to maintain close tolerances.
• Lighter as compared to steel wheels.
• Magnesium alloy has high impact and fatigue strength so they can stand vibration and shock loads.
• Aluminium alloy are easier to cast or forged and are less prone to corrosion

Disadvantages: High price

Applications: Cast wheels are used in car and forged wheels are used in heavy duty

1.5 Wheel Dimensions

The wheel size is the size designation of a wheel given by its diameter, width, and offset. The diameter of
the wheel is given by measuring the distance from one side of the wheel to the other, through the canter
point of the wheel. The width is the distance measured from the bead seat to the other bead seat. The offset
is the distance from the wheel's true centreline (half the width) to the wheel's mounting surface. A typical
wheel size will be listed beginning with the diameter (in inches), then the width (in inches), and lastly the
offset (+ or - for positive or negative, respectively).
For example, 17x8.5 +35, the wheel's diameter is 17 inches, its width is 8.5 inches, and it has a +35-positive
offset.

Positive offset

• Hub mounting surface is toward the front or wheel side of the wheel.
• It is common to find a positive offset in newer and front wheel drive vehicles.

Negative offset

• Hub mounting surface is toward the back or brake side of the wheels centerline.
• A negative offset wheel usually has a "deep lip"

zero offset

• Hub mounting surface is even with the centerline of the wheel.

2 Rim
Rim is outer circular part of wheel on which tyre is mounted and supported
2.1 Types
• Well base rim
• Flat base rim
• Semi drop centre rim
• Flat base divided rim

2.1.1 Well base rim

• Used for passenger car tyres.
• Well enables tyre to pass over the edge opposite side of rim
• Tyre gets to locked to rim on inflation, a slide taper is provided for this purpose.
2.1.2 Flat base rim
• The flat at one end is held in position by pushing the flanges inwards.
• Tyre can be mounted and removed easily
• Used in heavy duty vehicles.

2.1.3 Semi drop center rim

• Used in light commercial vehicles.
• Gives advantage of both well base and flat base rim
• Detachable flange makes tyre removal easy, while slight taper helps the tyre lock on rim.

2.1.4 Flat base divided rim

• Divided rim are in two sections, which are bolter together.
• Used in military and heavy duty vehicles.
3 Tire
A tire (or tyre ) is a ring-shaped component that surrounds a wheel's rim to transfer a vehicle's load from the
axle through the wheel to the ground and to provide traction on the surface travelled over.

3.1 Functions of a tyre:

1. To maintain contact between vehicle and ground by providing desired traction.
2. To support the load of vehicle.
3. Dealing with various forces acting on vehicle during its motion.
4. Providing cushion against shocks and damping them.

3.2 Properties of tyre:

Non-skidding
The tread pattern must be designed to permit least amount of skidding even on wet roads.

Uniform wear
The tyre wear must be less and uniform in order to maintain the non-skidding property.

Load-carrying
The tyre material and design must be able to ensure that the tyre is able to sustain the stresses due to
revolution.

Cushioning
The tyre should be able to absorb high frequency vibrations imparted by road surface and
provide cushioning effect.

Power consumption
The tyre absorbs some power due to the friction between the tread rubber and road surface and also due
to hysteresis loss (as heat).

Tyre noise
The tyre noise should be minimum when rolling.

Balancing
The tyre must be balanced statically as well as dynamically.
3.3 How to read tyre nomenclature?

Service Description

P205/75R x 15 92H
205 cross-sectional width in mm
75 aspect ratio
R radial construction
15 rim diameter in inches
92 load index
H speed rating (130 mph/210 km/h)
Some tires use letters at the end of the tire size (suffixes) to indicate special applications including the
following.
LT = light truck
ML = mining and logging
MH = mobile home
ST = special trailer
TR = truck
High-Flotation Tire Sizes

High-flotation tires have a size designation such as 33 x 12.50R x 15LT:

33 = approximate overall tire diameter in inches
12.50 = approximate cross-sectional width in inches
R = radial-type construction
15 = rim diameter in inches
LT = light truck designation

3.4 Why are tyre black?

To protect the rubber from harmful UV rays.

3.5 Types of Tyre

3.5.1 Conventional tubed tyre:

Plies – Layers of strong fabric which are built up to give the tyre its strength and shape. It’s made of rayon
material.
Tube - Which contains air under pressure. A non-return valve is attached with it. It is made of Butyl
Rubber.

Bead – Two rings that are made of steel wire and encased in rubber. They hold tire side walls snugly against
the rim and prevent tyre from coming off.
Tread – Rubber pattern Outer surface of the tyre that comes in contact with the road.
Side Wall – The sidewall is that part of the tire that bridges between the tread and bead. The sidewall is
largely rubber but reinforced with fabric or steel cords that provide for tensile strength and flexibility.
Breaker strip- A strip of fabric under the tread of a pneumatic tire casing, designed to protect the carcass.
Shoulder- The tire shoulder offers support and protection to both the sidewall and the tread. The shoulder
is one of the thickest parts of the tire, enabling the tire to more easily hold its form during cornering
manoeuvres.
Filler(apex)- The apex provides a cushion between the rigid bead and the flexible inner liner and body ply
assembly.

3.5.2 Tubeless tyre

A tubeless tyre is very similar to a traditional tyre; except that it has no tube inside. Air in the tyre is
retained between the rim and tyre itself, with the use of an airtight seal.

ADVANTAGES
• No silly punctures: A normal tyre usually gets punctured when the tube gets pinched between the
tyre wall and the rim. It may sound silly, but happens more often than you would expect.

• Ability to run at lower pressure: Air changes its pressure inside the tube and makes it common
for tyres to run at lower pressures. This further increases the chances of the tube getting pinched
with the wheel as mentioned before. This will not the case with tubeless tyres.

• Liquid sealant: Tubeless tyres can be filled with liquid sealants. If a sharp object puts a hole in a
tubeless tyre, the liquid sealant immediately oozes out and dries up; thus, sealing the hole. This
enables you to travel longer without having to worry about a puncture.
 • Air escapes slowly: In case you encounter a puncture, the air will leak very slowly in a tubeless
tyre; giving you enough time to pull safely over to the side of the road. A tube will let out air
immediately and can prove dangerous on a highway or when you are going at high speeds.
•
Lightweight: Tubeless tyres are lighter compared to tubed tyres.

• No unwanted friction: While driving at high speeds, a tubed tyre will have friction within itself.
This increases the tube temperature and there can even be chances of the tube exploding. A tyre/tube
explosion at high speeds calls for disaster. Tubeless tyres do not pose this risk.

• Stability: Since air is contained within the tubeless tyre itself, and not in a separate tube, high-speed
stability will be better.

DISADVANTAGES
• Difficult to fit: Tubeless tyres are difficult to fit on the rim as they have to be airtight against the
rim. Furthermore, only an expert can fit a tubeless tyre without getting the rim damaged.

• Punctures: If at all you have had a puncture and the tyre is flat, not everybody will be able to fix
it. Fixing tubeless-tyre punctures require special equipment; which not many will have.

• Cost: Tubeless tyres are expensive compared to tubed tyres due to the difference in components
used.

3.6 Tyre Construction OR Types of carcass (Tread)

3.6.1 Cross ply (or) bias ply type
• One of the oldest designs.
• The tire is constructed to form a single working unit.
• Nylon textile plies are laid across each other(30deg-40deg), running from bead to bead in alternate
directions.
• Number of plies depends on the size of the tyre and the load it has to carry.
• Same number of plies is used on the crown and the sidewalls.
• It does not use belts but it has thicker sidewalls, which can improve sidewall cut resistance.
• It Allows body of the tyre to flex easily and Improved cushioning, hence smooth ride on rough
roads.
• These tyres were used in classic cars.

Dis-advantages:
• Reduced traction at high speeds (due to sidewall flexibility) and increase rolling resistance.
• Two layers rubbing thus produce heat which would damage the tyre material.
3.6.2 Radial ply type

Radial – Ply tyres consist of a carcass ply formed by textile arcs running from one bead to the other.

• Each ply which is laid in an arc at an angle of 90 degrees to the direction the tyre rolls.
• At the top of the tyre crown (under the tread), there is a belt made up of several plies reinforced with
metal wire, laid on top of the carcass ply.
• These crown plies, laid one on top of the other, overlap at an angle determined by the type of the tyre.
• Remember the tyre tread depth must be not less than 1.6mm over the central three-quarters of the tyre
and must go all the way round the circumference in an continuous unbroken band with no bald patches
anywhere on the tyre tread.
• If radial and cross-ply tyres are fitted to the same vehicle, the radial-ply tyres must only be fitted to the
rear.
• Cross-ply and radial ply tyres must never be fitted to the same axle.
• Tyre pressures must be set to the manufacture’s recommendations.
• The tread and side wall must be free from large cuts, abrasions or bubbles

Advantages:
• Its shock absorbing capacity is 25% more than bias ply.
• Lower rolling resistance and hysteresis loss leads to less fuel consumption.
• Larger resistance to punctures, cuts and impacts in the tread area.
• Longer tread life because of less heat build-up in tyre.

3.6.3 Belted bias ply type

• This is a combination of radial and bias ply.
• Bias ply tyres with belts added to increase tread stiffness.
• Belts do not run around the sidewalls, they lay under the tread area only
• Belts and plies run at different angles.
• Offers some reduction in rolling resistance over a bias ply tire
• The belts increase the resistance of the tyre to punctures.
• Provides smooth ride and good traction.

3.7 Tyre Materials

• Modern tyres are made from a range of materials.
• Rubber is mostly synthetic, with carbon black added to increase strength and toughness, used in the
tread, this combination gives a long life.
• Natural rubber is weaker than the synthetic version. It’s used mainly in sidewalls.
• The plies are made from cords of fabric, coated with rubber.
• use a sophisticated selection process to create combinations that provide the required performance
characteristics and ‘hysteresis level’ of the tyre.
• The more you subject a tyre to flexing and deformation the more heat will build up within the tyre.
• Excessive heat is the enemy of a tyre so this builds up has to be kept under control.

3.8 Tire Tread

• Grooves in tread allow traction on wet surfaces
✓ Allow tire to flex without squirming
✓ Design is a compromise
• Sipes – small grooves in tread like knife cuts
✓ Clear water off the road
• Ribs pump water through grooves to back of tire
• Different tread patterns for different driving conditions
• Asymmetrical patterns improve wet performance
• Wear indicators are also called wear bars. When tread depth is down to the legal limit of 2/32", strips
appear across the tread.

3.9 Tyre terms:

3.9.1 Aspect ratio:

• The aspect ratio of a tire is determined by dividing a tire's section height by its section width. This
is described as a percentage of the tire width.
• Lower the aspect ratio, better load carrying capacity, less wear and higher cornering power.

•
3.9.2 Ply Rating / load range
The ply rating branded on a tire's sidewall identifies how much load the tire is designed to carry at its
industry specified pressure.

154-width of tyre in mm

151-% of height (i.e height=(151/154)X100%)

3.9.3 Speed Rating

3.10 Proper Inflation

3.11 Wheel Alignment Basics

• Caster is the angle of the steering axis of a wheel from true vertical, and has little effect
on tire wear
• Positive caster tilts the tops of the steering knuckles toward the rear of the vehicle
• Negative caster tilts the tops of the steering knuckles toward the front of the vehicle
• Unequal caster will cause the vehicle to steer toward the side with less caster
• Most common problem affecting caster is worn strut rod and control arm bushings
3.12 Camber
• Camber is the angle represented by the tilt of the wheels inward or outward from the Toe
centreline
• Positive camber has the top of the wheel tilted out, when viewed from the front
• Negative camber has the top of the wheel tilted inward when viewed from the front
• Camber is controlled by the control arms and their pivots
• Camber is affected by worn or loose ball joints, control arm bushings, and wheel
bearings

• Comparison of distances between fronts and rears of a pair of tires

✓ Alignment angle most responsible for tire wear
• Toe-in: tires closer together at the front
✓ Every 1/16" of toe-in results in 11 feet per mile scuff
✓ Tires move sideways for 11 feet out of every mile
• Toe-out: tires further apart at the front
• Causes of incorrect toe
✓ Improper adjustment
✓ Bent steering linkage
✓ Change in caster or camber adjustment
✓ Looseness in steering linkage due to wear
• Change in toe on one side of the vehicle
✓ Will be split through steering linkage with the wheel on the other side
• Front toe: adjustable on all vehicles
✓ Rear toe adjustable on some
3.13 Turning radius

➢ When turning: outside wheel must travel in wider arc than inside wheel

➢ Turning radius: alignment angle that controls arc traveled

➢ Also called Ackermann angle

➢ Tires toe out during turn

➢ Steering arms are angled inward or outward

3.14 Tyre Wear Diagnosis

• Check for foreign objects and pressure:

✓ Inspect the tyres for embedded objects in treads and remove them and look for signs of wear on all
wheels, including the spare.
✓ Check the pressure in the tyres.

• Check tread wear depth:

✓ Inspect the wear indicator bars. Tyres should have at least one sixteenth of an inch, or two
millimeters of tread remaining.
✓ The wear indicator bars are normally set at this depth.
✓ If the tread is worn down to that level or below, they are unserviceable and must be replaced.

• Check tread wear pattern:

✓ Check the wear patterns with the vehicle’s shop manual to indicate the types of wear that have
occurred.
✓ Causes of uneven wear can include faulty shock absorbers, incorrect front alignment angles and
wheels out of balance.
✓ Uneven tread and bald spots can indicate over- or under-inflated tyres and poor alignment.

• Check tyre for damage:

✓ Inspect the sidewalls of the tyres for signs of cracking from impacts with blunt objects.
✓ Carefully examine the tread area for separation.
✓ This is usually identified as bubbles under the tread area. Spin the wheel and see if it is running true.
3.15 Maintenance of a Wheel Bearing
1. Prepare the vehicle
2. Remove the bearing hub assembly
3. Remove the hub seal
4. Clean and check the old bearings
5. Inspect the bearing
6. Re-pack grease into bearing
7. Grease inside of the hub and dust cap
8. Re-install the bearings and seal
9. Inspect the sealing area of the spindle
10. Re-install bearing hub assembly

3.16 Factors affecting tyre life

1.Matching and installation of tires

Tires installed correctly or not directly related to the life of the tire, especially when the replacement tires.
Different tire types and patterns, due to different actual size and load capacity of the tires, must not in any
mix. Also, if you yourself cannot fully grasp the skills of replacement tires, we recommend that you go to
a professional tire shop or vehicle replacement at an authorized service provider.

2.Working pressure

Tire pressure is too low or too high, will affect the life of the tire. If the tire pressure is too low, the radial
deformation increases, excessive deformation of the tire wall on both sides, resulting in the tread shoulders
and wear phenomena, the tire temperature rises, it will seriously reduce the life of the tire.

If the tire pressure is too high, increasing the rigidity of the tire deformation and contact area is reduced, so
that the central unit pressure increases tread wear Caroline drama. Produce central tread wear phenomenon
that affects comfort and reduce tire life. Tests show that if we raise the pressure by 25%. Tire life will be
shortened by about 30%.

3. Tire load

The larger the load of the vehicle, the shorter the life of the tire, this is not to question the contents.
Especially in the case of overload more prominent. Regular tire manufacturers to produce tires are marked
with load index. Tires should be used within a specified load index corresponding to the maximum load.

4. Driving speed

Regular tire manufacturers to produce tires are marked with speed level index. Tires should be used within
a specified speed level index corresponding to the maximum speed.

5. Tire temperature

Vehicles in the process, the tire due to stretching, compression and friction, causing the tire temperature
rises. High temperatures easily exacerbate or even puncture the tire wear occurs.

6. Chassis status

Front, the rear axle parallelism, wheel alignment, brakes and chassis other parts working conditions will be
different degrees of technical conditions affecting the life of the vehicle tires. Once a serious traffic crash,
vehicle owners are sure to open the chassis to a professional repair station status checks and adjustments.

7. Road conditions

If the vehicle is a long gravel road or in the harsh road conditions, tire life will certainly be reduced. This
is no exception for off-road tires.

8. Driving habits

This is a factor related directly with the owners. Start too fast, sharp steering, emergency braking, high-
speed driving on poor road conditions of the lot, often when the tire rubs up and down curbs and parking
barriers, etc., can lead to severe tire wear, thereby reducing tire life.

9. Tire maintenance

Tire timely transposition, the appropriate choice of tread, ground maintenance routine, check the tire
pressure regularly and timely repair and are an important factor in the ground dug extend the life of the tire
tread in the gravel, and other foreign matter.

10. Vehicle maintenance

Many car repair experts say a vehicle to "30% repair, 70% maintenance"; do not wait until a failure occurs
before opening to the repair station maintenance. Periodic maintenance and extend tire life are also closely
related to the vehicle. Wheel alignment, steering knuckles, wheel bearings and suspension systems checked
regularly to maintain one less.
3.17 Why Tyre Pressure is Important
1.Incorrect tyre pressure not only adversely affects a vehicle's ability to brake, but also its stability and fuel-
efficiency.
2. A high pressure keeps the tyre from having enough grip on the road, which can lead the vehicle to hop
violently while passing over bumps and potholes.
3. High pressure also implies less traction, which can influence the responsiveness of the vehicle's brakes.
4. Low pressure means too much of the tyre's surface will touch the ground, which means increased friction.
Increased friction causes the tyre to heat up, which, in turn, leads the tread to wear out too quickly.
5. It is always safe to stick to the tyre pressure level advised by the car manufacturer.

3.18 Tyre trouble shooting

• Side wear of tyres
• One side wear of tyres
• Centre wear of tyre tread
• Uneven tyre wear
• Uniform rapid wear
• Rapid wear with feathered edges on the tread
• Tread cracking
• Tread or ply separation
• Loss of tyre pressure
• Radial tyre lead
• Radial tyre waddle

3.19 How to change a tyre

1. Prepare the car
• Apply the handbrake and remove all passengers from the car.
• Take the spare wheel and necessary tools out of the boot.
2. Position the wheel chocks
• Chocks prevent the car from rolling while jacked up.
• Position a chock on the opposite wheel to the one with a puncture.
• For example, if your left-front tyre has a puncture, put a chock behind the right-rear wheel.
• If your left-rear tyre is flat, you need a chock in front of the right-front.
• Use chocks for both front/rear wheels (as appropriate) if you have them.
• Bricks or large rocks can do the same job if you don’t have a dedicated chock.
3. Loosen the wheel nuts
• It’s easier – and safer – to do this while the car is on the ground.
• You may need to lever off a plastic wheel trim first.
• Turn the wheel wrench anti-clockwise and loosen the nuts to the point where they can be turned by
hand (be warned – they may be tough to loosen).
• However, don’t remove them completely yet.
4. Jack the car up
• All cars have dedicated jacking points – consult your handbook to see where these are.
• Aim to position the jack at the side of the car, close to the punctured wheel.
• Placing a small plank of wood under the jack will help keep it stable.
• Raise the car slowly until the flat tyre is 10-15cm off the ground.
5. Remove the flat tyre
 • Fully loosen and remove the wheel nuts, then gently pull the tyre towards you until it comes free.
• Place it flat on the ground.
6. Mount the spare wheel
• Slide the spare wheel onto the protruding hub bolts, or in line with the wheel nut slots (warning: it’s
heavy to lift it off the ground to do this).
• Replace the wheel nuts and tighten them by hand.
7. Lower the car and tighten the bolts
• Use the jack to drop the car down slightly, so that the spare tyre is in contact with the ground.
• Now use the wrench to fully tighten the wheel nuts.
8. Fully lower the car
• Bring the car fully down to earth and remove the jack.
• Consider giving the wheel nuts a final check for tightness.
• Stow the jack and the other tyre in the boot, along with the rest of your equipment.
• Note: if your car has a space saver, the old wheel will take up more space in the boot.
9. Check the spare tyre pressure
• If you have one, use a tyre pressure gauge to check the spare wheel is fully inflated.
• Alternatively, drive carefully to a petrol station and use the gauge there.
• Pump up the tyre to the recommended pressure – as detailed in the handbook – if necessary.
10. Take your punctured tyre for repair

3.20 WHAT IS TIRE ROTATION?

Tire rotation means periodically changing the position of each of the tires on your vehicle. We should rotate
your tires as recommended by the vehicle manufacturer, or every 5,000 miles.
3.21 WHAT TIRE ROTATION PATTERN SHOULD I UTILIZE?
The tire rotation pattern that’s best for your vehicle will depend on the type of tire you’re using, whether
your vehicle is front, rear, all, or four-wheel drive, whether your tires are directional or non-directional,
whether or not your tires are the same size on the front and rear of your vehicle, and whether you have a
full-size spare that can be rotated through as well, unlike a temporary spare..
SAMPLE VISUAL:
3.22 FOR TIRES THAT ARE OF UNIFORM SIZE AND NON-DIRECTIONAL:

1. REARWARD CROSS
For vehicles that are 4-wheel, all-wheel, or rear-wheel drive, the rearward cross pattern is recommended.
Rear tires are moved to the forward axle and kept on the same side of the vehicle while the front tires are
moved to opposite sides of the rear axle.
2. X-PATTERN
Recommended for front-wheel drive vehicles such as light-weight trucks and sedans, all tires are moved
diagonally, meaning tires are switched from one axle to the opposite as well as being repositioned from one
side to the other.
3. FORWARD CROSS
This is the most common pattern for front-wheel drive vehicles. The front axle tires are moved directly
back while the rear tires are moved up diagonally to the opposite side of the front axle.

3.23 FOR TIRES THAT ARE OF UNIFORM SIZE AND NON-DIRECTIONAL WITH A FULL-
SIZE SPARE TIRE:
In order to insure that all of the tires on your vehicle have even tread wear, you’ll want to be sure to rotate
your full-size spare tire along with the other four. This is especially vital for all-wheel or 4-wheel drive
vehicles where even small differences can put undue strain on your car’s drive train.
1. REARWARD CROSS (REAR-WHEEL OR 4-WHEEL DRIVE VEHICLES):
Both rear axle tires move directly forward to the front axle while the spare tire moves to the right side of
the rear axle. The right front tire moves diagonally back to the left side of the rear axle while the left front
tire becomes your new spare tire.
2. FORWARD CROSS (FRONT-WHEEL DRIVE VEHICLES):
Rear tires are moved diagonally to opposite sides on the front axle while the right front tire becomes the
new spare tire. The spare tire is positioned on the right side of the rear axle while the left tire on the front
axle is moved directly back into the left rear position.
SAMPLE VISUAL:
3.24 FOR HIGH PERFORMANCE AND DIRECTIONAL TIRES:
1. SIDE-TO-SIDE (FOR DIFFERENTLY-SIZED PERFORMANCE TIRES ON THE FRONT
AND REAR AXLES)

All tires are switched with their same-sized partner and remain on the same axle. The two rear
tires switch to the opposite side with one another while the two front tires do the same.

2. FRONT-TO-BACK (FOR DIRECTIONAL TIRES)

All tires are moved from one axle to the other but remain on the same side of the vehicle. For example, the
front left tire is moved to the left side of the rear axle while the rear left tire is repositioned on the left side
of the front axle.