One Tuesday night in October, I drove home with a flat tire. The next morning, I drove to work with a flat. The only problem was the stream of drivers pulling up alongside, honking and signaling.
Normally, I appreciate such concern. But in this case, all I could do was keep driving and smile. I was testing a set of Michelin's Pax System run-flat tires, mounted on a BMW X5 sport-utility that I had picked up at Michelin's suburban Detroit warehouse.
Warehouse manager Bob Brown III told me about the Pax system, allowing me a look at two versions of the support ring that keeps the car rolling when the tire goes flat. At Brown's suggestion, I drove the X5 to the office with the tires inflated so that I could get a feel for the vehicle. Then I used the small tool that Brown had given me to pull the stem-valve core from the driver-side rear tire, watched the tire rapidly deflate and drove home.
My evening commute - about 25 kilometers on streets across Detroit's east side and into the suburbs - was surprisingly smooth. The X5's ride seemed a little more wobbly than normal. Bumps in the road were more noticeable; there was a little more roll in turns; but, frankly, the difference was minimal. If I had not known that I had a flat tire, a monitor provided that information. I drove over 65 kph quite a bit and more than 80 kph once or twice.
The only problems were the normal ones: drivers darting in front of me and Detroit city bus drivers who are either unable or unwilling to drive in a single lane. After a while, I forgot about the tire and began experimenting with the X5's Steptronic transmission - a manually shiftable automatic.
When I got home, I reinflated the tire with a portable compressor. There was no apparent damage to the rubber, although it was warm to the touch, while the other tires were cool. Then I deflated the passenger-side front tire. Brown had suggested that I try flattening different tires, saying that the effects of a flat in the front could be more pronounced.
He was right. The next morning, the ride was more wobbly, and the X5 dipped more on turns. When I took my hands off the wheel, the vehicle immediately drifted to the right. I never felt in danger of losing control, but I never felt like pushing the X5, either. I was quite conscious that, although I could keep driving, I was indeed riding on a flat, as the dreaded 'wap-wap-wap' sound reminded me.
It seems clear that Pax allows the motorist to drive safely, if cautiously, on a flat. Although the total distance I traveled was about 65 kilometers, I see no reason to question Michelin's projected range of 200 kilometers. But you would be wise to get to a service station sooner than that.