Tyres to Tarmac
It’s the home stretch ladies and gentlemen, we’re almost finished with the mathematical rubbish I keep banging on about… at least for another few weeks.
So we’ve been through a reasonable gamut of information on how tyres behave, at least scientifically, to a pretty fundamental level.
Part I of Tyres to Tarmac was all about how tyres go around corners, and why being ‘on rails’ is best for the A686, not Island Bend. On its coattails, we delved into the war on weight in Part II, and the effect it has in corners, not so much on straights (or as our colonial kinfolk would call them, ‘straightaways’).
How do we use that information? How can we club racers benefit from engineering that MotoGP riders might never have any input on in their entire careers? In this final segment of our Tyres to Tarmac trilogy, we’re going to lead you to ways you can translate this knowledge into better understanding and hopefully lower lap times or even race wins.
That right there is a pyrometer you can get from pretty much any larger bike or car racing shop. This particular Longacre Deluxe Digital Pyrometer goes for £135, but others from Demon Tweeks go for about 50 quid less. It measures the sub-surface temperature of the tyres (close to the cords that hold the rubber in place), where heat is most consistently indicated.
Is it worth the money? Watch any race, club, national, or international, where manufacturer tyre technicians are among the paddock crew. What do they have on their person as soon as riders return to the pits? A pyrometer, ready to measure the temperature of fresh-off-track rubber. Comparing measurements across the entire tread to the ‘optimum’ for whichever compound they happen to be riding on can indicate where a tyre is being over- or under-utilised.
From there, unfortunately it’s an open book. It could be a suspension change, a throttle input change, a braking change, an engine tuning change, anything really. The funny thing about tyres is that everything you do or change on the bike affects the tyres in one way or another. So working in the reverse direction and starting with the effect to find the cause, the tyres will tell you pretty much everything you need to focus on when it comes to setup changes.
This brings us in a roundabout way to the subject of reading tyres, and understanding signs of wear. Cold tearing, hot tearing, cupping, heat cycling, discolouration, geometry wear, spring wear, the list goes on. To cover the topic in this article would be an injustice to the many top-draw suspension service companies and technicians out there, let alone crew chiefs. It would be an oversimplification of a science that’s not simple at all.
No legitimate engineer, crew chief, or suspension technician can close their eyes, spin around five times, point to a random tyre and just say, “yep, you need 3mm less spring preload”. It’s not possible. There are so many other factors, more questions that need to be asked before one brings the gavel down on a setup change.
Reading tyres itself can lead you to conclusions, sure. If you have what looks like a waterway in a rice paddy running down the side(s) of your tyre, you’re probably well under-inflated and should increase the pressure to above that of a party balloon. If a tyre isn’t wearing on the edges, yes there is probably room for more lean angle to be taken advantage of. However, even the most experienced of rubber shamans know that there is always something else involved, some other factor or factors.
As we said in Part I, they are the only parts of the motorcycle that interact with the tarmac (no, your elbow doesn’t count). That being the case, what on the motorcycle influences the tyres? Everything – the chassis, suspension, aerodynamics, engine, and of course the rider.
So how are you supposed to use the three-part series Tyres to Tarmac to go faster?
Think. Think about your tyres. Because everything you do on the bike, from tucking in tighter to braking later to accelerating earlier to standing up faster, is just a way to make those bloody rubber doughnuts work more efficiently.