Extracted from Roadracing World 2007 Trackday Directory
Article by Michael Gougis.
It is an oft-repeated cliche: The only part of the motorcycle in contact with the road is the contact patch of the tyres (if you are dragging some other parts regularly, something may be badly wrong - or about to go badly wrong).
But rushing out and buying the stickiest, gooiest tyres you can find may not be the hot set-up for track day riding, particularly if you are new to the sport. At best, it may be a waste of money. It can make for an unpleasant day with an ill-handling machine. New and experienced riders alike will benefit by making the best possible tyre selection for their track day experience.
One of the advantages of riding track days, as opposed to racing, is that there is no need to chase every last fraction of a second in lap times through mechanical advantage. In other words, there's no reason whatsoever to slow down to adapt your pace to your tyres. You are looking for the experience of pushing to the edge of your nerve, skills and available traction; it really doesn't matter if your lap times are off by 0.5 sec. So the range of tyres available to the track day rider, who is not looking for ultimate grip at all costs, is wider, and the rider can balance traction, intended uses and need for mileage when selecting tyres.
Be honest with yourself about your skill level and what you plan to use the tyres for, and you will have a better chance of selecting the tyres that will work with you and not against you.
Street Tyres vs Racing Tyres vs Track Day Tyres
"The difference comes down to compounds, construction and shapes" says Jeff Johnston, who works in technical sales support for Pirelli's motorcycle operations in North America. The company distributes Pirelli and Metzeler motorcycle tyres and brings a depth of experience to building tyres for sportsbikes - Prrelli of course is the supplier of the spec tyres in World Superbike.
"Track day tyres work in an envelope of temperatures that are more narrowly focused than the street tyre, but not as narrowly focused as the full on race tyre." Johnston says "Its not like it used to be,- there are tyres that bridge the gaps- but there are still differences."
Simply put, the full-on race tyre is designed to provide maximum grip at temperatures that pro riders can generate on the tack while spinning the rear and sliding the fronton a litre bike thats cranking out 180+ horsepower. The tyre surface itself becomes soft, generating mechanical grip that allows for the insane looking lean angles that a modern racing slick can generate. Pirelli's race tyres operate best at temperatures in the 165 - 180 degree F range.
The street tyre, on the other hand, has to provide traction at the other end of the temperature extreme - down near freezing. It has to provide traction not just in the cold but when the road is slick with moisture. Chemical grip is what is required here, and it comes from juggling the tyre rubber compound.
"The race tyre excels at those elevated temperatures but clearly, at lower temperatures it doesn't provide the same level of grip. And the street tyre, at maximum, is not operating near the temperatures a racer sees on the track" Pirelli markets its Diablo Corsa III and the Metzeler M3 and Racetech tyres for track day riders; Johnston points out that the Corsa III is the spec tire for the European 600cc Superstock Championship series.
Jay Wright, a distributor of Bridgestone racing tyres and the founder fo the Bare Bones Machine - whcih creates some of the most wicked-fast single-cylinder racebikes in the nation - says he encourages track day riders to stay with the supersport tyres intended for street use, particularly if the track is cold.
"Avoid the competition stuff", Wright says. "They are temperature sensitive. If you get them working in the right temperature range, they are great."
Generally, track day tyres are designed to wrok in a temperature renge thats a bit higher than a street tyre, without the rider having to push as hard as Ben Spies to get the temperatures up high enough to create the maximum amount of grip.
What Are Your Needs?
One other area which street tyres differ from track day tyres and race tyres is in the shape of the cross section' Generally for street use, tyre manufacturers use a smoother, more constantly rounded radius that provides a more linear response to steering inputs. The racier the tyre, the more triangulated the profile, particularly in the front. The sharper cross section helps quicken steering and puts a larger contact patch on the ground at maximum lean angles, increasing the available side grip - just the tip for top-flight riders who go from straight upright to max lean in one quick, fluid snap. That same profile might not feel reassuring to the new rider ith clean, unscuffed knee pucks, the rider who's not yet comfortable with just whipping the bike to fully heeled over.
Tyre sizing may also affect the way your mtorocycle handles significantly. Aside from the obvious safety concerns (make sure the tyre doesn't rub againstanything and remember some brands will grow in diameter at speed) different sizes will also affect chassis geometry.
Many streetbikes come with 60- series front tyres, while race compounds come in 70-series on th front. The difference in diameter can be almost a full inch; that means your front axle will be sitting about half an inch higher than the factory designed it to do. The bike will be harder to turn and it will struggle more to follow the line in a corner, wanting to 'push' th front toward the outside of the turn.
If you are going to slap on the biggest rear slick you can find, you can inadvertently raise the rear the bike, thus putting more weight on the front and potentially making the bike less stable in long fast sweepers.
Racers make small incremental changes in suspension settings most fo the time. A full turn of preload is a large change; they adjust ride heights a millimetre at a time. Throwing the wrong size tyre on the bike can 'adjust' its suspension in ways you don't want.
If you are convinced you want the latest, larger racing tyres, you may have to buy a racing shock with an adjustable clevis mount (to change the ride height) and/or fork extenders to allw the front and rear ride heights (and thus chassis geometry) to be set correctly.
Tyre diameter is so critical to handling that when Bridgestone introduced its new line of BT002 Racing Street track day tyres, it specifically made available a 190/50-17 size rear tyre tha more closely approximates the size of the stock rear tyre than the typical 190/55-17 or 190/60-17 racing rear tyre. A 55 or 60- series tyre is taller than stock, and unless your bike has adjustable ride height on the rear shock, it will affect the handling. For 2007. the Honda CBR1000RR, the Suzuki GSX-R1000 and the Yamaha YZF-R1 all come stock with the 190/50-17 rear.
"This way, the track day rider who doesn't have ride height adjustment - or doesn't want to have to work with ride heights - can put a stock sized tire on their bikes and keep the suspension geometry the same". says Bob Graham, Motorcycle Product Manager for Bridgestone Firestone North American Tyre.
Assuming that a softer tyre is a better tyre may also be a mistake, although the worst that happens is that riders tend to go through tyres more quickly than they need to, says Steve Brubaker, owner of Race Tyres Services, which provides Dunlop tyres to tracks east of the Missisippi River.
"While it all really depends on the motorcycle and the rider, for a lot of track day guys, they are not giving up anythinga the pace that they are riding by going with a harder compound. We have found that our D209 tyre in a hard 190 rear, has shown more mileage on the big 1000s. It is not like they are 'hard' tyres. If you are comparing a 'hard' racing tyre to a touring tyre, its still far softer. They are really on 2 different scales.
"Its possible for a rider who is hard on the throttle with poor suspension setup to destroy a rear tyre in 2 sessions. And if thats what you are looking to do and you dont mind investing the the rubber, spinning it up and kicking it out can be alot of fun" Brubaker chuckles. "Hey, its part fo the reason we ride bikes. But many riders will be fine on a harder compound".
Michelin offers a range of aimed at a range of track day riders; all you have to ask is, what kind of riding do you really do?
"The 2CT, the replacement for the old Pilot Power is a dual compound tyre that Michelin also recommends for an intermediate rain race tyre'. says Dale Kieffer of Racer's Edge Performance, a distributor of Michelin street and competition in the Western USA.
"We have alot of guys who run these for track days, guys who do 70% of their riding on the street and 30% on the track" Keiffer says. "The grip they provide is not so heat sensitive, so it works will in intermediate conditions".
Michelin's Power Race is a hybrid of a track tyre construction with a more street oriented compound that heats up more quickly than a full race tyre, aimed at the rider who spends 70% of their time on the track and 30% on the street.
Michelin even makes a set of slicks tha it markets to track day riders. The TD1200 front and RD1800 rear based on Michelins's old and often praised H2 street tyre which are reasonably priced - about $75 less than the company's racing slicks for a set - and - heat cycle well and last for quite a while.
There is no such thing as the 'best' tyre - there's just the best tyre for you.
Common Sense That Really Does Make Sense.
Just because the tyres got you back and forth to work on Friday does not - not - mean they are the best choice for the track on Saturday. "If you are going to do a track day, start with something new, not something you have got a bunch of miles on" Brubaker says.
Since it is not a race, you can actually take a couple of laps to slowly bring the tyres up to temperature. Doing this has all kinds of benefits. The tyre heats evenly, minimising the chances of tearing the tread. You have an opportunity to see the track, work on your lines and see the condition of the track. And if there is something mechanically wrong with your bike or your head... better to find out at a slower speed.
Talk to the tyre vendors and listen to their advice. CHECK your tyre pressures and visually check your tyres in the pits. Better to detect a cut or chunk in the pits than in a high speed sweeper.
Don't buy used racebike take-offs for track use. Some riders will take used DOT tires and put them on street bikes, its still not the best idea. The racers took them off becoz they are worn. Do you really want these to be your only contact with the road??
PS - Type until fingers pain. Wahahahahah!!! But I really hope it helps you PG and Sepang Trackies like me.