2013 Porsche 911: Tire Pressure Overboost
December 20, 2013
We recently took our 2013 Porsche 911 in for its 20,000-mile service. After the service, however, we noticed that the tires were aired up (at 39 psi front / 46 psi rear) to beyond max spec. We don't recall entering the 911 in a fuel economy contest or wanting to see how it handled the slalom with contact patches the size of silver dollars, so we checked into this.
This happened before, as Mr. Magrath previously observed. As he noted, not only did the service tech pump 'em up higher than the specs shown in the standard door jamb location, but even those official numbers (36 front / 44 rear) are too high. Those specs are for a fully laden car that will be driven occasionally at top speed. Well, the first scenario is very rare, given the 911's tiny rear seats. And the second is essentially impossible, given traffic, safety concerns and, oh yeah, speed limits.
The additional yellow sticker seen next to the white one advises that "For better driving comfort, the tire pressures in the owner's manual may be used." So for our needs (and likely 99.9 percent of U.S. 911 owners), we again selected Comfort Pressure/Part Load, which dictates 31 psi front / 34 psi rear. Even at those settings, the 911 has no problem making quick, enjoyable work of winding roads like those we enjoyed recently.
Looks like Porsche's service departments need to learn to RTFM.
John DiPietro, Automotive Editor @ 21,067 miles