Why brand new cars that have never been used ‘age’ and why tyres deflate… 

Hi Bennett, 
I wish to appreciate your article on leaving cars “home alone” for long. How moving a car from time to time solves several unseen problems was well captured. Would you mind telling us why brand-new cars in showrooms age? Also, why do tyres deflate even when static?
Jonah

New cars do not start life with any absolute immunity from the factors that affect a used car that is left “home alone” for a long period. The rate of degradation may be less, but it exists. 

Bear in mind that “new” is a relative term. Cars do not get from a factory in France or Japan or Germany to a showroom destination elsewhere in a completely airtight box placed on feather pillows.

More often, they are driven from the factory doors to an outdoor finished vehicle park where they sit in the dust and weather for some time, they are then put on low-loaders and trains, packed in containers or sail the seven seas in ro-ro ships, stand waiting for customs clearance in salty seaside ports, and are then driven or carried across the country by road to pre-sale inspection centres. 

That journey can be severe enough that manufacturers, having burnished them to a super shine, then spray them with a special matt coating to avoid damage and corrosion. The recipient showroom removes that with special solvents and polishes the vehicle back to a shine. When it is parked on a showroom floor, it is already not absolutely new, and over, perhaps weeks or months, on display is effective “home alone”.

Diligent workshops will of course start it up, run its engine, keep it clean and hopefully move it around a bit. But it is unless kept in an environment as pure as an Intensive Care Unit, subject to some degree of ageing. 

If the vehicle does not sell in a showroom in, say Madrid or Athens, it may be transferred to another market; say, Nairobi. Probably via a dead-stock car-park for several months, then a repeat of the whole shipping process again. More time. More exposure. More ageing. That is why it should be given a very thorough check and important physical attention (including possible replacement of perishable parts), and should not be sold as, or for the same price as, a “new” vehicle. 

The ins and outs of air 

Pneumatic (filled-with-air) tyres and tubes were traditionally made of natural rubber, which is not 100 per cent airtight; the material itself is very slightly porous. In the old days, regularly topping up the air pressure was routine. Modern tyres are made with a mixture of natural and synthetic rubber (like styrene-butadiene, whatever that is!) and, along with fabric and wire, a number of other chemical compounds like carbon black and silica. 

The new compounds are effectively airtight, but the valves which enable a tyre to be inflated or deflated also rely on a rubber seal that can become worn or degraded or loose, and air at high pressure - contained by a seal between the beading and rim and spinning around in a flexible casing suffering all manner of bumps and squashings, and even stabbings creating microscopically small holes – will almost inevitably find a “way out” from time to time.

However rarely this happens, and in however small a quantity, the change is always a one-way street. More air at normal atmospheric pressure will never get “in” to a tyre pressurised to a higher psi. 

If the tyre and rim are in near-perfect condition, there may be little or no deflation if there is no load or movement. But “perfect” is a very fussy (and unusual) standard.

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