Avoid Mixing VR Rated Summer Tires with ZR Rated - Technical Service Bulletin
Tires: Technical Service Bulletins
Tires (VR-Rated Summer ) - Do Not Mix With ZR Rated
Group
4
Number
8910
Model
All
Part Identifier
4440
November 22, 1989
Subject:
VR Summer Tires
ATTENTION:
Service Manager/Service Technician
Models affected:
944, 911 and 928 series cars.
The statement ("Note: Do not mix VR and ZR rated tires on one car.") which appeared in Technical Bulletin 8801 Group 4 pages 2 and 3 is now invalid.
Please delete it from all copies of this bulletin.
Due to reduction or discontinuation of the production of VR summer tires by the manufacturers, mixed mounting of VR and ZR rated summer tires is
now permitted providing the approved tires have identical design. The statement that only tires of the same make and type may be mounted on one car
remains applicable.
If it is only necessary to replace one or two tires on a car having VR rated tires, mixed mounting of VR and ZR rated tires is approved when the
replacement tire is identical in design to the original tire. If all tires are being replaced, only ZR rated tires approved for Porsche models should be
installed even on older models.
Refer to the tables for identical design VR and ZR rated summer tires approved for use by Porsche:
944 Series Survey of Identical Design "VR" and "ZR" Tires
The "VR" and "ZR" tires are identical in design and may even be mounted mixed on one car for which "VR" tires are specified.
911 Series Survey of Identical Design "VR" and "ZR" Tires
