The skinny on space savers

While a space-saver spare wheel can be a step better than a tyre inflator kit or a set of run-flats, it still leaves a wider tread and a smaller sidewall to be desired – a full-size spare wheel and tyre, in other words. However it’s increasingly uncommon for new cars to be equipped with a full-size spare and some of them lack even the space required to stow one.

The Mazda 6 test car is among the many fitted as standard with a space-saver, and we couldn’t resist throwing it on to see what happened. That the handling and braking performance suffered didn’t surprise us, however the fact the magnitude of the lost handling performance was only as bad as having one underinflated front or rear tyre certainly did.

With the pizza-cutter at the front left, the slalom time increased by seven percent ( and peak lateral G was down a corresponding seven percent), with Ren observing “lighter steering feel and terrible understeer.”

With the skinny wheel and tyre at the right rear, Ren experienced his one and only half-spin of the Tyre Test. On a clean run, the time increased further, up by 12 percent compared with a set of full-size rubber.

During the brake tests Ren noted “lots of brake-forcedistribution ( EBD) kicking in with the ABS.” With the space-saver on the front, the wet braking distance was up by 2.4 metres or 10 percent.

Think the space saver was poor during cornering and braking? Imagine asking it to do both at once in a collision avoidance manoeuvre. The lesson, then, is to use your space-saver to get home or to a tyre store; don’t drive around on it for days. Not only will you wear it out, you’ll be carrying a significant safety impediment.