Tyre Pressure Monitoring System

[Mottie]

I always get the optional space saver spare kit, having had this experience in the past. I had reason to use it last week. Took 10 mins to fit.

When we bought an Evoque, I made them chuck in a space saver spare wheel kit as part of the deal. It was shown on the invoice as £400 and then deducted. That included the foam insert, wheel, Jack, wheelbrace and hold-down kit. Got me out of trouble twice with two irreparable punctures. Mind you, one time when we were away in the Peak District and I had a puncture, we had to move the dog crate to the back seat as the standard 245/45/20 punctured wheel would not fit in the recess the spacesaver came out of meaning we couldn’t close the tailgate with the dog crate in there.

Both our Golf and our A3 have spacesaver spares and have come in handy.

 

[Avocet]

The industry refers to them as "direct" and "indirect" tyre pressure monitoring. The former is the sort that uses battery operated pressure transducers with little wireless transmitters in each wheel. They can give pressure readings even when stationary. The "indirect" are the ones that do it from the ABS system. Obviously lower maintenance, but also lower accuracy and no absolute pressure readings, just relative ones.

The manufacturer is free to use either, provided it meets the sensitivity requirements in the regulations. That's hard to do for indirect systems on light cars with very low profile tyres - especially if they're run-flats, because they just don't change their rolling circumference enough unless the pressure drop is way too big to comply with the regulation.

The main driver has been to reduce CO2 emissions (people driving round on soft tyres), but also, to a certain extent, safety - especially with run-flats where some owners won't notice, even when the tyre is virtually flat!