Tyres are round, black and made of rubber. That’s about all you need to know, isn’t it? Well, if all you want is the cheapest set for your road car, possibly, but for hillclimbing there’s a while science behind these vital components.
For starters, the tyre is the only thing connecting any car to the road’s surface. In motorsport, you want that connection to be as strong and consistent as possible, but it also has to be matched to the car’s performance. There’s no point fitting the latest high-tech super-sticky slicks to a pre-war machine as neither car nor tyre will give their best. Equally, a modern single-seater running on ancient hoops will be unmanageable.
The Motor Sports Association (MSA) lays down rules and regulations governing which tyres can be fitted to different classes of car, which gives competitors clear guidance over which ones they can run on their car. For example, if you compete in a road-going class, the tyres must come from either List 1a or 1b as they cover all of the approved rubber that is allowed and road-legal. So, no slicks for these drivers.
On the other hand, single-seaters and dedicated race cars are permitted slicks in most instances. There also wet-weather tyres they can use for when the Heavens open. Not that the weather would ever do that at a hillclimb…
So, choosing a tyre is simply a matter of picking one from the MSA’s list? Not quite, as different drivers have their own preferences a certain make and type of tyre can work brilliantly on one car but not another.
There are also different compounds to consider. This is where the tyre manufacturer varies the amount of materials in the construction to offer different peaks of performance. As well as rubber, tyres are made from carbon and silica, as well as having an inner core to support the outer shell. Silica is what gives tyres their grip, but it also wears out quickly, so it’s stabilised with the carbon.
For hillclimb tyres that cover short distances, you want maximum grip right from the start, so they have very soft silica-rich compounds. This is also why you see many drivers warming up the tyres before the start line to generate heat in the rubber to further soften them.
Another common sight in hillclimbing is single-seaters with plastic wrapped around the tyres as they approach the start line. This is then whipped off at the last moment. Support crews do this to keep the tyres free from dirt that could otherwise become stuck in the very soft rubber. You’ll also see drivers and crews scrubbing the tyres with brushes to keep them free from debris for the same reason.
There are plenty of other considerations when choosing a tyre for a hillclimb car, such as inflation pressure, sidewall depth, carcass construction and tread patterns. However, for anyone looking to get started in hillclimbing, the important thing is to make sure your car’s tyres are safe and legal, and then get signed up for motorsport thrills.