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Tyre Pressure & Heat
Originally posted by @Exonoesis
Tire carcass heat:
As many of you posted from all over the world, you are all shooting in the dark on tire carcass heat from track to street to race etc. There is no data available from manufacturers as it is too hard a number to pin down. Why? We all ride differently, different road surfaces, temperatures, speed, ability, different power, geometry and on and on it goes...... So let's make this really basic and make things a little more complicated each day so that by the end of this week you can address any tire situation anywhere in the world with a logical approach founded on solid reasoning.
Street tire pressure is a balancing act between ability, longevity and grip. Budget no issue - low pressures for better grip. Need to make the tires last? Higher pressures for longevity. As a generalization that is a safe start. That being said, street tires have a working range where carcass heat is critical. As you cannot take a pyrometer probe with you and ride on the street at a consistent pace, it is impossible to judge carcass temps that way. If you resort to pressure, you should see a gain of 3-5psi on the street no matter what the brand or model of tire. That can indicate that the tire is getting warm and probably close to optimal carcass temps but you will need to ride 20 miles/35km to get the tire warm. Less gain and you have too much air, more and you started with too little.
You have an environment which is much more conducive to tire pyrometer probes to get accurate carcass temps. Why - you are at the track in a controlled environment and consistent pace and load can be maintained - critical to assess carcass temps. Should you do this first thing in the morning? No - you are cold, the bike is too as is the track. Wait until your 3rd session when the pace is good, smooth and consistent. These are your tires, your bike, your ability and your lap times so adjust for your needs not what someone else tells you!
That being said you HAVE to have the right compound for track temps and track surface, so don't complain when you get that wrong even though carcass temps are right!!!!!
Track temps shifts rapidly with cloud cover and wind and that change can create a massive change in carcass heat. So during each practice session you should be checking carcass temps to see where they are after 4 laps if the above factors change. Don't shortcut this process. Track carcass and track temps with lap times so by the race, you can be 100% confident that the tire will be working at the correct temp to give you max grip and longevity!
That being said you HAVE to have the right compound for track temps and track surface and that can change rapidly so you should have 2 sets of wheels for this contingency and don't complain when you get that wrong even though carcass temps are right!!!!!
Infrared versus probe
Infrared gives you surface temps only, so it is perfect for measuring track temps. You can therefore understand that this type of tool only gives you surface temps of the tire that millisecond. Then it changes again and again - try it and stand by a tire and watch it cool down in the hot pits. If you are using this data all you are seeing is the absolute surface not the core, so you have a huge number of variables to cover to make this tool worthwhile.
The probe gets 4-5mm into the carcass and takes core temps which are far more important. If the core of the tire is at the right heat, so is the rest of it, throughout the entire tire. Watch any event, all major contenders and see that everyone has a tire probe checking carcass temps.
Here's an example of the probe I use (FYI: I have relationship with this company):
Street riders should use pressure gain only as roads, conditions, traffic flow etc can cause incredible fluctuations in carcass temps.
No matter what you ride at the track and when racing the general rule of thumb is the carcass getting to somewhere around 170-200F from all the data we have in getting optimal heat into the carcass that stays there over the last 10 years from track side tuning. AGAIN - correct compound is critical otherwise you are wasting valuable time and very expensive tires.
There ends the sermon for day one. Everyone start sharing, right now. I want this information to reach 2-3 million riders each day so please do your part!
BY DAVE MOSS