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Why use tyre warmers....

Discussion in 'Technical and Troubleshooting Torque' started by cejay, Feb 16, 2008.

  1. Heat cycles and how tyre warmers help

    I listen to Motogpod, a podcast from a guy in the Us that discusses Motogp in particular but motorcycling in general. In recent weeks, he's covered track days and club racing. Today he interviewed a manufacturer of tyre warmers and why they're useful.

    He covered off the blueing that indicates that a tyre is starting to lose its grip.

    Basically, a race tyre (or soft compound road tyre) leaves the factory without being fully vulcanised. The process of running at race speed actually finishes off the cooking process. This isn't a problem until the tyre cools down. In the process of cooling, some of the chemicals (stabilisers and other additives) come to the surface, both drying the tyre out and then oxidising on the surface. The blue is the oxidisation.

    So how does a tyre warmer help? Well, if you can keep the tyre at a certain temperature, I can stop the process of drying and leaching, which is ultimately the determiner of grip. This is where warmers that allow temperature setting are useful as they can keep the tyre at just the right temperature and not get it too hot. Over a weekend of racing, the rider keeps their warmers on the bike all the time they are not being used. Now, the life of the tyre is determined by the amount of rubber that is left on the tyre.

    He estimates that 5-6 heat cycles is a practical limit for most race tyres.

    Track day punters who do track days without using warmers are killing their tyres over the day. Although the tyres may have plenty of available tread, their chemical composition has changed dramatically.
  2. I haven't heard of soft compound road tyres being limited so much by heat cycles. Any examples?

    But yeah, apart from saving you money, there's nothing like the confidence you get even just practicing with warmers. Just check that your tyres are ACTUALLY hot when you head out. Can be very nasty going straight into a flying first lap full of confidence, only to find that one warmer mustn't have been plugged in properly. My tip of the day. ;)
  3. I am specifically referring to homologation tyres. My BT002's 'Race' compound are race tyres, but with a tread pattern. Some of the Pirelli's are the same? I am not talking about Pilot Roads or Powers.

    Flux has some (painful) memories of the effect of heat cycles.

    I've used warmers for some years now, but with the last year of racing, it's imperative to use them. Even for track days, it's great to go out and not waste 2 laps pootling around.
  4. Nice to know. I never realised.
  5. Good find.
    I totally agree. For example my last set of tyres with warmers for my trackie lasted me 5 trackdays, where as the set before without warmers lasted only 2. They are starting to go blue and slip a fair bit, so i got some new pirelli slicks, cost a leg though

    Any idea what temp warmers should be set to when not riding?
  6. It was mentioned in the podcast but I can't remember. Bob Hayes makes these podcasts and they're always good value.
  7. Cheers. I had a listen.

    Between sessions temp should be 51-57 degress to stop the tyre from hardening.
    Working temp is between 62-85
  8. I leave mine on 70, and haven't cooked a set, plus plenty of the good quality warmers don't have an adjustable thermostat. Should I really be dropping the temp to the 50's if I'm not riding for a couple of hours?
  9. Yes. Still getting pains in the ankle 9 months later after a break of the talus, and have a nice metal plate and scar from the broken wrist with some lost mobility and strength.

    Tyres were the Pirelli Dragon Supercorsa Pro Special Compound tyres, which are basically homologated supersport racing tyres. Come in 4 flavours (SC 0/1/2/3). 0 = softest, 3 = least soft. They are road legal, but they heat cycle and lose traction after about 6 cycles (possibly less). Good for a weekend race-meet, bad for anything else if you're pushing the limits.

    When fresh, you'll feel like you can drag the bars (and on a low enough bike with wide enough bars, you probably could), with a nice progressive controllable slide if you push too hard. After 6 or so heat cycles, traction becomes greatly reduced (well - by greatly reduced - imagine about the same sort of grip as some sport-touring road rubber), and if you push hard enough - they'll just let go at lean angles that weren't even close to their limit when fresh.

    Caught me by surprise - and I've got the scars and injuries to prove it.

    The Pirelli Supercorsa Pro Street Compound (which are the tyres fitted to Daytona 675's and Ducati 1098's and 848's as stock) are a different compound that is more resistent to heat cycling, being more of a regular road compound. Still sticky as all get out, just not at the same level as the Special Compound tyres, but retain a consistent level of grip throughout their life.
  10. How does it 'feel' actually riding one of these real racing tyres? Compared to normal/soft road tyre? Is the difference huge ? I know that motogp/wsbk guys use it so it must be good, but at 'our' speed how does it improve riding or lap times ? Thanks.
  11. Just comes down to more traction. You can lean the bike further. Dragging the elbows, if you were so inclined to try, is easy enough to do without the tyres sliding. You can get onto the throttle earlier out of corners, and feed it on more quickly and be at full throttle while the bike is still cranked over a fair way. You can go faster through corners 'cos the tyres have more grip.

    If you're not at the limits of your current tyres, they won't make an ounce of difference. They might stick in really abnormal situations where street rubber might let go (for example, going through a patch of gravel on the road and the tyres will hold onto the road like glue if there's any solid bitumen to grip onto), but aside from that, they'll feel a bit like your regular road-going rubber.

    Good to stick them on when doing regular track days (I was at the time) and you can slowly learn to approach their limits, which really is quite staggering just how far the bike can be leaned and how much throttle you can use before they even think about protesting.

    They are essentially slicks with tread in the middle, but not on the edges, so basically like slicks where you need it most.
  12. It make a huge difference. I put some Pirelli Diablo suberbike slicks on my bike, these are just the slick version on the Pirelli Supercorsa. Compared to supersoft dunlop GPRa10 it: was more stable at lean, didnt really slide and when it did it wasnt really a slide, improved braking, lean angle, Confidence inspiring.

    Improved laptimes dramatically. I was doing about 5sec faster at PI then before. I think because they give better consistency and confidence.

    One downside. Alot of fooling around with tyre pressure, tyre warmers.
  13. Pretty much the same as what the other guys said. Unless you're on the limit of your street tires, the only lap time gains you get will be through confidence.

    IMO, it's better to stick with the street tires for track work, and learn how to find the limit with them first. It's not as full on as trying to find the absolute limit of a soft slick, and you can concentrate on tire adhesion instead of the sheer terror of your new found speed.
  14. I remember reading, can't remember where, even street compounds on 2CTs and the like have limited heats cycles in the range of 300 or so.
    Considering they last me around 5000k at best, that's an average of 16.666k per trip, so I don't think it's much of a problem.