Tires/Wheels - Summer Recommendation Summary
Group4
Model
All
Part Identifier
4412
Number
9312
November 2, 1993
Subject:
Summer Tire/Wheel Rim Summary
ATTENTION:
Service Manager / Service Technician
Models Affected:
968 1992-on
911 Carrera 214 1989-on
928 GTS 1993-on
Concern:
The following contains the latest summer tire and wheel rim recommendations for Porsche vehicles. For general information on mounting, balancing and tire care, refer to Technical Bulletin Book E, page 199 (Technical Bulletin Group 4, Number 8813), Technical Bulletin Book 1, page 91 (Technical Bulletin Group 4, Number 9202) and the Workshop Manual.
N0, N1 or N2 Specification Numbers
The specification numbers are cast in the side wall next to the tire type casting. N0, N1 and N2 tires must not be mixed on one vehicle, even if they are the same make tires. The one exception to this is when using the tire combination 225/45 ZR17 front axle and 275/35 ZR17 rear axle on the 911 American Roadster the front tires have the specification indicator "NO" and the rear tires have specification "N-."
Important:
The 17 inch wheels are double hump rims. The wheel's inner hump is the "normal" design used on other Porsche wheels, but the outer hump is asymmetrical. The asymmetrical hump prevents a flat tire from moving off the wheel rim. This provides improved control for safely stopping the car. So long as the tire sidewall is not damaged, the car can be driven, with extreme caution, a short distance to a safe place to change the tire.
When breaking the tire bead on these wheels, start at the tire valve. When mounting the tire, start the outside bead on the wheel in the area opposite the valve stem.
Note:
When installing 17 inch wheels, the color coded wheel stud (and wheel lock) should be indexed opposite the tire valve.
Tire pressures are only applicable for Porsche approved tire makes and types. Measure tire pressure only when the tire is cold (approx. 20~ or 68~ F). Do not under Inflate tires. Air pressure increases as the tires get hotter. This increased pressure must not be reduced.
When installing wheels/tires that were not originally installed at time of production, the wheel/tire clearances in the wheel house should be checked and reworked as necessary.
Model Affected: 968
Tire Pressure:
Front Axle Rear Axle
16 in. wheels 2.5 bar (36 PSI) 2.5 bar (36 PSI)
17 in. wheels 2.5 bar (36 PSI) 2.5 bar (36 PSI)
Porsche approved tire size and wheel dimensions:
Porsche approved summer tires for 968:
Quantity Part Numbers Description
2 951 331 611 02 Spacer
10 904 341 671 00 Wheel stud
10 999 182 003 36 Wheel nut
Always check for proper tire clearance on the front and rear axles. Rework these areas if necessary.
2. Summer tires Bridgestone Expedia S-01 N1 225/45 ZR 17 and 255/40 ZR 17. This make and type of tire is the first Porsche approved tire that has a rotational direction with an asymmetrical hump. The tires for the left and right side are different.
Tire markings: In the area of the Bridgestone name is an arrow that indicates rotational direction. At the end of the arrow the indicator outside or inside appears. See Figure 1.
In addition, new tires that have not been driven have these additional markings.
Left tires: One white band on the outside circumference.
Right tires: Two white bands on the outside circumference (see Figure 2).
3. These tires may be installed mixed.
Wheel Rim summary for summer tires, 968:
Models Affected:
911 Carrera 2/4 1989-on
911 RS America 1993-on
911 American Roadster
911 Speedster 1994-on
Tire Pressure:
Front Axle Rear Axle
16 in. wheels 2.5 bar (36 PSI) 3.0 bar (44 PSI)
17 in. wheels 2.5 bar (36 PSI) 2.5 bar (36 PSI)
17 in. wheels with tire size 275/35 ZR 17 3.0 bar (44 PSI)
Porsche approved tire size and wheel dimensions for 911 Carrera 2/4:
Porsche approved tire size and wheel dimension
for 911 Speedster and RS America:
Porsche approved tire size and wheel dimensions for 911 American Roadster:
Wheel notes:
1. When installing 9-1/2 J X 17 AH wheels on the rear axle a 17 mm spacer must be installed on each rear wheel hub. See Tire notes 1, in this bulletin.
2. When installing 17 inch wheels on 911 Carrera 2/4, the steering stop washers, left and right, must be replaced with stop washers Part Number 964 347 325 02 (arrow in Figure 1). Refer to 911 Carrera 2/4 Workshop Manual Volume IV, page 48-3.
3. The bumper cover plastic edge should protrude slightly in the bumper cover to fender joint area. If the fender metal edge protrudes, only the metal edge should be reworked (cut) in the area of the outer mounting screws on the left and right side to ensure adequate tire clearance (arrow in Figure 2). After cutting metal, apply rust prevention paint.
4. On the front fender, from approximately 150mm above the rocker panel to the front bumper, the inner fender edge has to be bent up. Do not cut or grind this edge off. Also the metal edge of the fender has to be cut off. See Figure 2.
5. No tire chain clearance.
Please replace pages 7 & 8 of Technical Bulletin Group 4, # 9312, dated 11-2-93 with this page.
Wheel Rim summary for summer tires:
911 Carrera 214
911 Speedster
911 RS America
911 American Roadster
Model affected:
928 GTS
Tire pressure:
Front axle Rear axle
17 inch wheels 2.5 bar (36 PSI) 2.5 bar (36 PSI)
Porsche approved tire size and wheel dimension:
IMPORTANT:
As of M.Y. 1994, the 928 will not have RDK system. Under no circumstances should these wheels be installed on a vehicle equipped with RDK.