Tires/Wheels - 17 Inch Wheel and Tire Approvals
Group4
Number
9301
Model
928
Part Identifier
4412
January 19, 1993
Subject:
17 Inch Wheel and Tire Approvals
ATTENTION:
Service Manager/Service Technician
Models Affected:
1987 to 1989 without RDK (H,J, K) 1990 and 1991 with RDK (L, M)
Concern:
Installing 17 inch wheels on 1987 through 1991 928's
Installation:
On 1987 to 1989 928 vehicles, the following general information applies when installing Porsche 17" tires and wheels:
A. Front and rear fender well lips must be reworked to assure adequate clearance for tire travel.
B. All wheel housing components such as brake lines, brackets, etc. must have adequate clearance during suspension travel.
C. The rear tire pressure for 17" summer tires is 2.5 bar (36 PSI) at 20~C (68~F). Rear winter tire pressure remains at 3.0 bar (44 PSI). See note at the end of this bulletin.
D. Snow chains cannot be used with summer tires. Vehicles with winter tires may use Porsche snow chains, Part Number 911 361 924 OR only.
E. On 1989 928 GT, the distance ring between the wheel and the rear brake disc is not used.
On 1990 and 1991 928 vehicles with RDK, all of the information above applies, plus this additional general information when installing Porsche 17" tires and wheels.
F. New tire pressure sender brackets must be installed. They are Part Number 928 341 087 01 front (2 each) and Part Number 928 331 083 01 rear (2 each).
G. When installing 17" Porsche summer tires and wheels, new wheel pressure switches must be installed in the rear wheels. The switches are needed due to the reduced pressure specification. Part number for the switch is 928 361 022 00. It is a 2.5 bar switch. Quantity of 4 switches are needed. See **note at the end of this bulletin.
H. A new emergency wheel is needed. The original emergency wheel cannot be used once the vehicle has had 17" wheels installed. Part number for the emergency wheel is 965 362 030 01.
I. Once a 1990 or 1991 928 has had 17" wheels installed and all the necessary changes done, it is recommended not to change back to 16" wheels.
J. When transferring or installing new pressure switches, always use new seals and torque to proper specification (see Workshop Manual Vol. IV, page 44-31).
**NOTE: When 17" wheels are installed on the rear axle, the pressure switches are changed to 2.5 bar type. The 3.0 bar type switches should be returned to the customer in the event 17" winter tires are to be installed.
Parts Information:
Model 87-89 without RDK
Approved Wheels
Wheel Position Size Offset Part Number
Front wheel 7-1/2J x 17AH 65 mm 965 362 124 05
Rear winter wheel 8J x 17AH 52 mm 965 362 126 01
Rear summer wheel 9J x 17AH 55 mm 965 362 128 00
Model 90-91 928 with RDK
Wheel Position Size Offset Part Number
Front wheel 7-1/2J x 17AH 65 mm 965 362 164 05
Rear winter wheel 8J x 17AH 52 mm 965 362 166 00
. Rear summer wheel 9J x 17AH 55 mm 965 362 168 00
Approved Tires Yokohama A-008 P NO
Summer Version: Bridgestone Expedia S-01 NO
Michelin MXX3 NO
Approved Tires Bridgestone WT05
Winter Version: Continental TS 750
Pirelli Winter 210 Performance
Semperit Directional Grip
Approved Tire Sizes:
Summer Version: 225/45 ZR 17 Front
255/40 ZR 17* Rear
Winter Version: 225/45 R 17 90 H M&S* Front & Rear
*Note:
Snow chains may not be used on vehicles with summer tires due to insufficient wheel housing clearance. On vehicles using winter tires only, Porsche snow chains with Part Number 911 361 924 00 may be used.