Tyre manufacturers chase the business of having their tyres fitted to new cars very assiduously. Of course it helps if you own a large slice of the car company, as does one such company, but most compete strenuously for the business.
This because they know that further down the track, the car buyer will have to replace his tyres, and they can have a profound influence on his or her choice, particularly if the customer has ‘had a good run’. Besides, there is the compatability of the (probably) un-used spare with any other tyre, the calibration of the A.B.S. braking system, compatability with the inbuilt traction control sensors, and many other factors to be considered. To the customer, it might just get too hard, so they take the easy choice first.
Important to the tyre manufacturer is that the car company requirement helps build the volume of that sized tyre, which spreads the development costs over a greater number of units.
So when you come to replace your tyres, what do you do?
If you’ve been reading our panels of information, you know that there is a wide choice of tyres available on the Australian market. What do you do about the spare? Leave it there? If you do, the next time you have to replace tyres, it will be six years old, not three. You will be missing out on six years development and improvements in tyre design. It will be a little crazed in the sidewall rubber from the heat in the boot, and the rubber will be harder and less flexible. So it seems like a good idea to use it, by matching it with an equivalent tyre, if you can still buy one the same. Tyre fashion changes too, you know.
Is your car front wheel drive or rear wheel drive? If FWD, the front tyres wear out twice as fast as the rears, normally, because they are doing all the work- steering, braking, driving. The rears hold up the corner, and come along for the ride. So probably you are up for two new tyres on the front first.
A matched pair of tyres on the one axle won’t upset the calibration of your traction/braking systems. If one tyre is worn out, the other part worn, buy two, put the part worn tyre in the boot or the garage. It’s false economy to only put one new tyre on an axle when the other is almost worn out. The new tyre rides better, the drive system is balanced, and the alignment is as the designer intended. There is also less risk of punctures with new tyres.
If your car is rear wheel drive, dependent on the type of rear wheel suspension, and whether you have diligently rotated your tyres in either a 4 wheel or five wheel rotation (including the spare), you may find that you are up for five new tyres at once. Shock! Horror! That blows the budget! Most of us leave the spare in the boot though. So wear is much more evenly balanced around the car, and it is likely that you have the choice of two or four tyres to be replaced immediately.
It would be a rarer circumstance where you replace only one tyre. That would likely be due to damage. If the remaining tyres ‘still have plenty of meat on them’, you could assume that one is the spare, so less worn, so match the new tyre with that on the same axle. The one that comes off goes in the boot, but pump it up first to close to the maximum so that you can forget it till you need it next. Everybody else does! Just be aware that it will probably be on a dark and stormy night in the rain, because that’s when you are most likely to get a puncture.