The Tireless Question of Tyres
It is often said that when it comes to fashion, the wheel always turns its full circle. But when it comes to tyres, I don’t think this neat metaphor applies. I don’t see wheels getting smaller in diameter or tyres becoming higher in profile any time soon.
The evolution of tyres in Australia
In the early postwar years and for a long time before that, diameters were typically 16 or 17 inches. The rims were narrow and the tyres tall and, yes, skinny. Some cars had two and a half inch wide rims – that’s only a touch over 6cm! The early Holdens had 15 inch wheels and then came the FE in 1956 with 13s. It was thought that smaller wheels accentuated the long-low-wide look in vogue during this period. The Mini was launched in 1959 (1961 in Australia) and rode on tiny 10s.
Then, slowly, things went the other way. In 1978 the first Holden Commodore had 14s as standard with trendy ‘cast alloy’ 15-inchers as an option. These were shod with low-profile 60-series tyres.
By the turn of this century 16-inch rims were the norm with sportier models having 17s or 18s. Today 19s and 20s are far from rare and the occasional Hummer is optioned up with 30-inch wheels.
Changing to big wheels
If you’re keen to fit bigger diameter, wider wheels to your car, you also have to think about the rubber with which they will be shod. It is important to make sure that the rolling circumference does not change significantly because that will affect your car’s gearing as well as the accuracy of the speedometer.
The price of tyres
The price of tyres is subject to the inevitable economies of scale. Choose a popular size and the price will be attractive. But rare tyres can be eye-wateringly expensive. Jaguar switched to metric tyres for its 1986 XJ40. Few makers followed. Tyres to fit these original rims are now unaffordably dear and most owners have changed their wheels to imperial sizes. At least it’s nice for some old-fashioned dudes to realise that the entire world has yet to go metric!
Tyres, grip and longevity
Tyres are styled and tread patterns are there for show as well as grip. This trend probably began back in the days of the Bridgestone Steel Cat.
Never buy tyres simply with long life in mind. The tyre that lasts forever does so because it offers poor grip in the dry and negligible grip when you need it most – in the wet.
Other factors to consider when choosing tyres
Other factors to consider are noise, comfort and suitability to dirt roads. Even braking distances can vary according to the rubber chosen. If you choose a tyre dealer who stocks plenty of brands you’re likely to get an honest appraisal. The country of origin no longer matters. Once European brands were esteemed over Japanese, then Japanese over Korean. I’ve driven on Korean treads that outperformed far more expensive prestigious Europeans.
The further bush you go, the sillier it is to have ultra-low profile tyres which are vulnerable to being pierced by a rock or even a large stone on an unmade road (so the best you could do with your Hummer on 30-inch wheels would be to park where others could gape at it).
Check tyre pressures regularly. As a rule of thumb, I like about 40 psi all round if I am doing an interstate trip. More air means better fuel economy: think how much extra energy is required to ride a pushbike when the tyres are low on air. Higher pressures also bring improved grip (up to a point – you don’t want 50 pounds!), improved steering response and shorter braking distances. The only disadvantage is a slightly harsher ride, which is a tiny price to pay for greater safety.