No. 88-21

911 (997)
Manufacturer's Certificate
88/21
ENU
4440
4
Approved Wheels and Tires (88/21)
Revision:
This bulletin replaces bulletin Group 4 20/09, dated May 26, 2011.
Model Year:
As of 2010
Vehicle Type:
911 Turbo (997)/911 Turbo S (997)
Information:
Approval status: September 2021
WARNING
Driving with different tires (mixed tires)
•
Uncontrollable vehicle handling

Only use tires of the same make and type, with the same speed index and the same specification code
(N0, N1, N2, ...) on a vehicle.
Summer Tires:
Tire size
Tire make and type /
Notes
Label value (Link to EU database)
Bridgestone Potenza RE050A N1
(Inside/Outside)
Label value currently not available
235/35 ZR 19
(87Y) and
305/30 ZR 19
(102Y) XL
Michelin Pilot Sport PS2 N2
(Inside/Outside)
FA: https://eprel.ec.europa.eu/qr/408700
For all vehicle types
RA: https://eprel.ec.europa.eu/qr/412234
Pirelli P-Zero N2
(Inside/Outside)
FA: https://eprel.ec.europa.eu/qr/594212
RA: https://eprel.ec.europa.eu/qr/594214
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Winter Tires:
ENU
Manufacturer's Certificate
88/21
Tire size
Tire make and type /
Notes
Label value (Link to EU database)
For all conditions
Nokian WR N0
(Inside/Outside)
235/40 R 18 91V
M+S and
295/35 R 18 99V
M+S
Label value currently not available
Pirelli Winter 240 Sottozero Series II N2
(Inside/Outside)
FA: https://eprel.ec.europa.eu/qr/594284
RA: https://eprel.ec.europa.eu/qr/594285
Nokian WR N0
(Inside/Outside)
235/35R 19 87V
M+S and
295/30 R 19
100V XL M+S
Not for vehicles with
Porsche Ceramic
Composite Brake
(PCCB)
for areas with a lot of
snow
Not for vehicles with
Porsche Ceramic
Composite Brake
(PCCB)
For all conditions
Label value currently not available
Pirelli Winter 240 Sottozero Serie II N1
(Inside/Outside)
FA: https://eprel.ec.europa.eu/qr/594258
For frequent highway
trips
RA: https://eprel.ec.europa.eu/qr/594262
Information
N... = Specification code of the tire, e.g. "N0", "N1", "N2" ... The complete "N ..." code of the tires in
question must be shown on the tire sidewall near the tire type designation.
Instructions for correct mounting of the tires are also given on the tire sidewall. If there are no mounting
instructions on the tire sidewall, the tire must be mounted so that the DOT marking is visible from the
outside.
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Arrow with inscription “Rotation”
= directional mounting
“Inside/Outside” inscription or “Left” or “Right”
= mounting on specified side only
Arrow with both inscriptions “Rotation” and
“Inside/Outside”
= directional mounting on specified side only.
Arrow with both inscriptions “Rotation” and “Left”
or “Right”
= directional mounting on specified side only.
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911 (997)
Manufacturer's Certificate
88/21
ENU
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Information
If a tire is damaged and it is not possible to determine with absolute certainty that there is no ply damage
- with all of its consequences - or if the tire was thermally and/or mechanically overloaded due to a loss of
pressure or other prior damage, replace the tire in question for safety reasons.
Repairs to "V", "W", "Y" and "ZR" tires are not permissable, as well as the use of inner tubes in tubeless
tires. Please inform your customers accordingly. It is advisable to mount winter tires at temperatures
below 45° F/7°C , because the driving characteristics of summer tires are reduced at low temperatures.
Extremely low temperatures can cause permanent damage to summer tires.
WARNING
Incorrect tire pressure
•
Uncontrollable vehicle handling

Adjust the tire pressure according to specifications. Never allow the pressure to fall below the minimum
pressure.

Check age of tires. Replace tires that are more than 6 years old.

Perform visual inspections.

Use only tires recommended by Porsche.
Tire Pressure:
Tire pressure for summer and winter tires
Wheel size
Part load
Full load
FA
RA
FA
RA
18-inch wheels
2.3 bar
(34 psi)
2.7 bar
(40 psi)
2.5 bar
(37 psi)
3.0 bar
(44 psi)
19-inch wheels
2.3 bar
(34 psi)
2.7 bar
(40 psi)
2.5 bar
(37 psi)
3.0 bar
(44 psi)
Information
The tire pressure applies only to the tire makes and types approved by Porsche, and is specified for cold
tires (approx. 68° F/20°C ). The tire pressures must never be lower than the specified values.
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Sizes:
ENU
Manufacturer's Certificate
88/21
Permissible tire and wheel sizes (RO = rim offset in mm)
Tires
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Wheels
Notes
Not for vehicles with Porsche
Ceramic Composite Brake (PCCB)
Front: 235/40 R 18 91V M+S and
Rear: 295/35 R 18 99V M+S
8 J x 18 H2, RO 57
11 J x 18 H2, RO 51
Front: 235/35R 19 87V M+S and
Rear: 295/30 R 19 100V XL M+S
8.5 J x 19 H2, RO 56
11 J x 19 H2, RO 51
Only winter tires
Snow chains can be fitted
Front: 235/35 ZR 19 (87Y) and
Rear: 305/30 ZR 19 (102Y) XL
8.5J x 19 H2, RO 56
11 J x 19 H2, RO 51
Only summer tires
Snow chains cannot be fitted
Front: 235/35 ZR 19 (87Y) and
Rear: 305/30 ZR 19 (102Y) XL
8.5J x 19 H2, RO 55
11.5 J x 19 H2, RO 50
Only summer tires
Snow chains cannot be fitted
AfterSales
Only winter tires
Snow chains can be fitted
911 (997)
Manufacturer's Certificate
Wheels:
88/21
ENU
4440
4
Overview of Porsche wheels for summer and winter tires
Identification on the inside/outside of the wheel disc:
Wheel size, rim offset (RO) in mm, Part No. and Porsche logo
Front: 8 J x 18 H2, RO 57
Part No. 997.362.137.01
Rear: 11 J x 18 H2, RO 51
Part No. 997.362.143.00
18" Carrera IV wheel
Front: 8,5 J x 19 H2, RO 56
Part No. 997.362.157.05
Rear: 11 J x 19 H2, RO 51
Part No. 997.362.163.02
19-inch Turbo II wheel
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Manufacturer's Certificate
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Front: 8,5 J x 19 H2, RO 56
Part No. 997.362.156.05
Rear: 11 J x 19 H2, RO 51
Part No. 997.362.162.02
19-inch Turbo wheel
— Only available wheel sets
will still be used —
Front: 8,5 J x 19 H2, RO 55
Part No. 997.362.156.55
Rear: 11.5 J x 19 H2, RO 50
Part No. 997.362.162.56
19-inch Carrera Sport wheel
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911 (997)
Manufacturer's Certificate
88/21
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Front: 8,5 J x 19 H2, RO 55
Part No. 997.362.157.56
Rear: 11.5 J x 19 H2, RO 50
Part No. 997.362.163.56
19-inch Sport Classic wheel
Front: 8,5 J x 19 H2, RO 56
Part No. 997.362.157.06
Rear: 11 J x 19 H2, RO 51
Part No. 997.362.163.04
19” RS Spyder wheel with central lock
Information
Improper handling can damage the wheel surface.
Carry out tire removal and mounting using a bead holding-down device only.
Use a leather pad on the rim flange to support the valve insertion tool.
Only use the Porsche centering clamping set for balancing.
Do not use brushes to clean the wheels because brushes can cause deep scratches that cannot be
removed by polishing.
Never use solvents or other chemical substances on tires.
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Wheel
Mounting:
ENU
Manufacturer's Certificate
88/21
using wheel bolts:
Tightening torque when wheels mounted using silver wheel bolts (up to model year 2011): 130
Nm
Tightening torque when wheels mounted using silver wheel bolts (as of model year 2012): 160
Nm
Tightening torque for securing wheels using black wheel bolts: 160 Nm
using central wheel lock:
Tightening torque 600 Nm (442 ftlb.)
WARNING
Incorrectly installed snow chains
•
Uncontrollable vehicle handling

Do not exceed the maximum speed of Speed 30 mph/50 km/h.

Observe installation instructions from the chain manufacturer.
Snow Chains:
Porsche offers the following snow chains as accessories:
Wheel Storage: •
•
•
•
•
•
•
•
General
Information:
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•
•
Tire size
Porsche Part No.
Type of snow chain
295/35 R 18 M+S
(not for vehicles with PCCB)
997.044.600.18
Link-type chain, quick fit
295/30 R 19 M+S
997.044.600.18
Link-type chain, quick fit
Tires must be stored in a cool, dry and dark room with adequate ventilation.
Tires must never come into contact with fuel, oil, grease or chemicals.
Do not store summer tires in storage areas with ambient temperatures of less than 5° F (-15° C).
Complete wheel & tire assemblies can be stacked for storage; we recommend that you increase the
tire pressure by approximately 6 psi (0.4 bar).
Optimum conditions for storage of the complete wheels are provided by the Original Porsche
storage trolley, Part No. 000.044.000.38.
If the tires are not mounted on wheels, it is best to store them in a vertical position.
We recommend that you turn tires stored in this position every two weeks in order to prevent flat
spots.
Tires that are stacked in a horizontal position will become severely deformed and cannot be seated
properly in the rim flange when they are mounted.
Always use new valves when changing tires.
Always observe any possible instructions concerning the rolling direction and/or specifying which
side the tires must be mounted on.
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911 (997)
Manufacturer's Certificate
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•
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88/21
ENU
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Coat the tire beads and humps with mounting lubricant before mounting the tire. This ensures that
the tire beads will slide over the humps easily.
In order to prevent the tire from turning on the wheel, avoid extreme driving maneuvers (acceleration
and braking) during the first 100 to 200 miles with new or recently mounted tires.
In order to optimize smoothness of rolling, it is appropriate - and necessary in individual cases - to
mount the tire in a certain (favorable) position with respect to the wheel (matching).
Matching (uncontrolled and controlled) is explained below: Uncontrolled matching:
•
Turning the tire on the wheel by 90° or 120° if necessary in order to achieve an acceptable value with
regard to rolling smoothness (true running, imbalance and weight distribution of balance weights).
Controlled matching:
•
•
•
With a balancing machine with matching program. In most cases, this produces an even better result
with regard to the rolling smoothness (true running, imbalance and weight distribution of the balance
weights) than can be achieved with uncontrolled matching.
Maximum permissible radial runout and lateral runout of the wheels < 0.7 mm. Maximum
permissible radial runout and lateral runout of the wheels with tires < 1.25 mm. Values < 1.50 mm
-ideally approx. 0.5 mm - are desirable.
The mounting pressure (seating pressure) of 58 psi/4.0 bar overpressure must not be exceeded
before both tire beads are evenly seated on the rim flange.
New Tires (Replacements):
•
•
•
•
If new tires are to be mounted or the tires of one axle are to be replaced, tires of the same make,
type and with the same specification code must always be used on each of the two axles.
If tires are replaced on one axle only, the different tread depth from that on the other axle can cause a
noticeable change in the familiar handling.
This is especially the case if new tires are mounted on the rear axle.
This effect decreases with increasing tire mileage.
When replacing a tire on an axle, make sure that the tread depth of the new tire does not differ from that of
the other tire on the same axle by more than 30 %.
Refer to WM 449503 for specific details of the vehicle you are working on.
•
•
>The 2mm specification will be given here.
> If there is none listed then the default is 30%.
Repairs to Tires:
•
•
If a tire is damaged and it cannot be determined with absolute certainty that there is no ply damage
- with all of its consequences - or if the tire was thermally or mechanically overloaded due to a loss
of pressure or other prior damage, we recommend replacement of the tire in question for safety
reasons.
Repairs to "V", "W", "Y", and "ZR" tires are not permissible, as is the use of inner tubes in tubeless
tires.
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911 (997)
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ENU
Manufacturer's Certificate
88/21
Tire Aging:
•
•
•
•
•
•
•
Tires age due to chemical and physical processes, which can impair their function.
Tires that are stored unused for an extended period harden and become brittle faster than tires that
are in continual use.
Hairline aging cracks can occur on older tires.
On tires in continual use, the kneading action activates the plasticizer in the rubber and thereby
prevents hardening and cracking.
Therefore, attention should be paid not only to the tread depth but also to the age of the tire.
Tires should not be older than 6 years.
The age of the tire can be determined via the DOT code on the sidewall, which indicates the
production date of the tire: e.g. DOT 2201= 22nd week of 2001.
Important Notice: Technical Bulletins issued by Porsche Cars North America, Inc. are intended only for use by professional automotive technicians who have attended Porsche service training
courses. They are written to inform those technicians of conditions that may occur on some Porsche vehicles, or to provide information that could assist in the proper servicing of a vehicle. Porsche special
tools may be necessary in order to perform certain operations identified in these bulletins. Use of tools and procedures other than those Porsche recommends in these bulletins may be detrimental to the
safe operation of your vehicle, and may endanger the people working on it. Properly trained Porsche technicians have the equipment, tools, safety instructions, and know-how to do the job properly and
safely. Part numbers listed in these bulletins are for reference only. The work procedures updated electronically in the Porsche PIWIS diagnostic and testing device take precedence and, in the event of a
discrepancy, the work procedures in the PIWIS Tester are the ones that must be followed.
© 2021 Porsche Cars North America, Inc.
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