Jaguar XK. Manual — part 60

243

Wheels and tires

R

TIRE GRADING

United States Department of
Transportation - Uniform Tire
Quality Grades

The following information relates to the
tire grading system developed by the
National Highway Traffic Safety
Administration which will grade tires by
tread wear, traction and temperature
performance.

Note: Tires that have deep tread, and
winter tires, are exempt from these
markings requirements.

Quality grades, where applicable, can be
found on the tire sidewall between the
tread shoulder and maximum section
width.

For example: Treadwear 200 Traction AA
temperature A

In addition to the marking requirements,
passenger car tires must conform to
Federal Safety Requirements.

Tread wear

The tread wear grade is a comparative
rating based on the wear rate of the tire
when tested under controlled conditions
on a specified government test course.
For example, a tire graded 150 would
wear one and a half (1.5) times as well on
the government course as a tire
graded 100.

The relative performance of tires depends
upon the actual conditions of their use,
however, and may depart significantly
from the norm due to variations in driving
habits, service practices and differences
in road characteristics and climate.

Traction

The traction grades, from the highest to
the lowest are AA, A, B and C. The
grades represent the tire’s ability to stop
on wet pavement as measured under
controlled conditions on specified
government test surfaces of asphalt and
concrete. A tire marked C may have poor
traction performance.

Temperature - A, B, C

The temperature grades are A
(the highest), B and C representing the
tire’s resistance to the generation of heat
and its ability to dissipate heat when
tested under controlled conditions on a
specified indoor laboratory test wheel.

Sustained high temperature can cause
the material of the tire to degenerate and
reduce tire life, and excessive
temperature can lead to sudden tire
failure.

The grade C corresponds to a level of
performance which all passenger car
tires must meet under the Federal Motor
Vehicle Safety Standard No. 109.

Grades B and A represent higher levels
of performance on the laboratory test
wheel than the minimum required by law.

WARNING

The traction grade assigned to
this tire is based on
straight-ahead braking traction

tests and does not include acceleration,
cornering, hydroplaning, or peak traction
characteristics.

Wheels and tires

244

L

TIRE GLOSSARY

Terms used

psi or lbf/in²

Pounds per square inch, an imperial unit
of measure for pressure.

kPa

Kilo Pascal, a metric unit of measure for
pressure.

Cold tire pressure

The air pressure in a tire which has been
standing in excess of three hours, or
driven for less than one mile.

Maximum inflation pressure

The maximum pressure to which the tire
should be inflated. This pressure is given
on the tire sidewall in lbf/in² (psi) and kPa.

Note: This pressure is the maximum
allowed by the tire manufacturer. It is not
the pressure recommended for use.

Kerb weight

The weight of a standard vehicle,
including a full tank of fuel, any optional
equipment fitted, and with the correct
coolant and oil levels.

Gross vehicle weight

The maximum permissible weight of a
vehicle with driver, passengers, load,
luggage, equipment, and towbar load.

Accessory weight

The combined weight (in excess of those
items replaced) of items available as
factory installed equipment.

Production options weight

The combined weight of options installed
which weigh in excess of 1.4 kg (3 lb)
more than the standard items that they
replaced, and are not already considered
in kerb or accessory weights. Items such
as heavy duty brakes, high capacity
battery, special trim etc.

Vehicle capacity weight

The number of seats multiplied by 68 kg
(150 lb) plus the rated amount of
load/luggage.

Maximum loaded vehicle weight

The sum of kerb weight, accessory
weight, vehicle capacity weight, plus any
production option weights.

Rim

The metal support for a tire, or tire and
tube, upon which the tire beads are
seated.

Bead

The inner edge of a tire that is shaped to
fit to the rim and form an airtight seal. The
bead is constructed of steel wires which
are wrapped, or reinforced, by the ply
cords.

WARNING

The temperature grade for this tire
is established for a tire that is
properly inflated and not over

loaded. Excessive speed, under-inflation
or excessive loading, either separately or
in combination, can cause heat build-up
and possible tire failure.

245

Wheels and tires

R

PRODUCTION OPTION
WEIGHTS

(USA only)

This table lists the production options
weights. To calculate the curbweight of
your vehicle, add the weight of all
production options, including optional
alloy wheels and spare wheel, to the
basic curbweight for your vehicle.

Note: The table only lists optional
equipment that weigh more than 3.0 lb
(1.4 kg).

Note: The weights listed under Wheels
and tires give the increase in weight over
a standard set of four wheels: the figure
only needs to be added to the curbweight
once.

WARNING

Do not exceed the weight limits
specified on the TIRE LOADING
INFORMATION label - See TIRE

INFORMATION LABELS (page 247).

Weight

lb

kg

Curb weight, no options fitted

-

-

See WEIGHTS (page 267).

-

-

Production options

-

-

Jaguar Premium Surround Sound System

13.23

6.0

Sirius Satellite Radio

2.87

1.3

16 way luxury sport seats

7.72

3.5

Adaptive Front Lighting System

3.31

1.5

Wheels and tires

-

-

Normally aspirated engine:

-

-

18 inch wheels (Venus)

0

0

19 inch wheels (Carelia)

25.6

11.6

20 inch wheels (Senta)

38.8

17.6

19 inch wheels (Sabre painted), Run-flat tires (no temporary use spare
wheel)

11.3

5.14

Supercharged engine:

-

-

19 inch wheels (Jupiter)

0

0

20 inch wheels (Senta)

16.8

7.6

20 inch wheels (Cremona)

13.7

6.2

Wheels and tires

246

L

Steps for determining correct load
limit

1. Locate the statement, The combined

weight of occupants and cargo
should never exceed XXXX kg or
XXXX lb on your vehicle’s placard).

2. Determine the combined weight of

the driver and passengers that will be
riding in your vehicle.

3. Subtract the combined weight of the

driver and passengers from XXXX kg
or XXXX lb (weight given on placard).

4. The resulting figure equals the

available amount of cargo and
luggage load capacity. For example,
if the XXXX amount equals 1400 lb,
and there will be five 150 lb
passengers in your vehicle, the
amount of available cargo and
luggage load capacity is 650 lb: (1400
- 750 (5 x 150) = 650 lb).

5. Determine the combined weight of

luggage and cargo being loaded on
the vehicle. That weight may not
safely exceed the available cargo and
luggage load capacity calculated in
Step 4.

6. If your vehicle will be towing a trailer,

load from your trailer will be
transferred to your vehicle. Consult
this manual to determine how this
reduces the available cargo and
luggage load capacity of your vehicle.

The number and weight of passengers
will affect the cargo and luggage load
capacity. In the example above, the
cargo and luggage load capacity is 650
lb. However, if fewer passengers ride in
the vehicle, the luggage load capacity will
increase. If this vehicle carries three 150
lb passengers, the cargo and luggage
load capacity will increase to 950 lb: (3 x
150 = 450 lb, and 1400 - 450 = 950 lb).

If the passengers weigh more, the cargo
and luggage load capacity will decrease.

WARNING

Do not exceed the vehicle
capacity weight (the total weight
of driver, passengers and cargo)

given on the tire information label - See
TIRE INFORMATION LABELS
(page 247).

WARNING

The weight of accessories must
also be subtracted from the
available cargo and luggage load

capacity. If you are unsure of the weight
of any accessories fitted to your vehicle,
contact your Jaguar Dealer.

Overloading the vehicle will have an
adverse affect on braking and handling
characteristics, which could
compromise your safety. Overloading a
vehicle may also cause tire damage or
failure. Never overload your vehicle.

TOWING: The XK has not been designed
as a towing vehicle and Jaguar Cars
does not manufacture a tow bar for the
vehicle.