In its tireless effort to match driving pleasure with road safety,
Dieter Röscheisen is pushing it. On a wet track, he’s driving the ruby
In the test log, he writes, “The tire set on this vehicle is out of balance. A lot of steering corrections are necessary as the rear is much more agile. The loss of traction sometimes occurs much too abruptly. It does not conform to what we consider a well-functioning series production tire.” The judgment, then, is as follows: Failed in wet-surface handling.
These tires will not be approved, notwithstanding their better performance in other categories. In dry conditions, they’re perfectly drivable, with adequate safety reserves. But a tire for an over 50-year-old
Why all the trouble? Because some 70 percent of all
The tire models recommended by
The number after the N indicates the different approval series. For example, a tire was available in an earlier version, say with the dimensions 195/65 R15, for the
Beyond handling, tire aging is also an issue; this factor was also assessed in the current test. Tires, after all, are not unlike bread and butter: if you store them for too long, they become much too hard. The effect is particularly pronounced when a car that’s getting on in years is only seldom used, and sits in the garage much more than it is driven.
Owners who leave the same tires on the rims for years and do little more than check the tire pressure produce (entirely unintentionally) what are known in German as “wooden” tires. As time goes by, the rubber becomes brittle and gradually loses traction. At the age of five or so, a tire might not yet have reached the undrivable stage, but its capacity to provide the smooth ride that once distinguished it becomes increasingly compromised with advancing age.
A tire’s age is revealed by the DOT number on its sidewall. The number ends with a four-digit number composed of the week and year of production. DOT 1302, for example, stands for week 13 in the year 2002. A tire thus marked has by now reached a practically biblical age. To illustrate the characteristics of aged tires, one such set was recently put through the paces in the latest round of tire tests.
After a decidedly squirrelly drive with much sliding and swerving on the wet-handling test course, our tire expert Röscheisen rated the twelve-year-old tires rather critically: “In wet conditions they demonstrate very little traction, have poor braking performance as a result, and are therefore especially tricky to drive in cars without ABS due to the high locking tendency of the front wheels. In corners, they are slow to react. This leads to an uncomfortable degree of understeer, which is completely atypical for the standard setup of a
“The driving behavior of a
A completely different impression was left by a 185/70 x 15 tire for the
Never mind that the 356 B Super 90 from the
Simply mounting newly developed tires on the rims of the older models has proven problematic at
By Michl Koch
Photos by Bettina Keidel, Uli Jooß
Treating tires right
Counteracting the aging process: Tires are best kept like old wine
The effect of tire aging can be slowed down by applying due care in the storage process—as with good wine: tires age more slowly in a dark location with low temperatures. The best move is to store your tires for upcoming pleasure jaunts in the cellar while your finely tuned
There’s no need to throw out old tires as long as they still have some tread-depth. Driver training at the