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Always On Mod
1,844 Posts
Discussion Starter #1
Don't know how many of you know or know of Dave Moss?? I had the pleasure to meet him a couple years ago at a track day. Dave has ~20 years of testing and tuning knowledge and he's globally called upon for suspension tuning and advice. Dave's knowledge of all things sportbikes is phenomenal. Check him out at http://feelthetrack.com/

This week Dave is posting a series of articles on his Facebook page regarding tires. I'll post the articles on this thread for those of you who don't use facebook.

Always On Mod
1,844 Posts
Discussion Starter #2 (Edited)
Tire week! Everyone excited?

I'm going to give out a lot of info this week to help everyone globally. This will be going into the subscription section of the website so you get essentially a 'freebie' for the week. In saying that, donations to the cause are appreciated at my home page of www.feelthetrack.com via the PayPal tip jar (https://www.paypal.com/) using [email protected] and I will put out a reminder on that at the end of the week.

As this information is critical to ALL riders, please cut and paste all this information into forums, websites and rider groups that you belong to so we can make all riders safer. That's my mission and has been since 95, so every day I will be looking at the share numbers to see YOU are doing your bit for OUR community at large to save lives and reduce injuries.

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 tires.
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.

Track tires.
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!

Always On Mod
1,844 Posts
Discussion Starter #3 (Edited)
4,716 read the first post and there were 50 shares (thank you for that!) - can we do better today on the %age of shares to readers to get this information to our community please? Thanks!

Day 2: What do you use to inflate your tires?

I figured that would create an instant emotional response to get your attention!

Street riders will get air from anywhere usually. Track riders from the track day service provider and racers from either their own supply or from the race tire service brand provider at the event.

Has a percentage of water vapor in it naturally. When we get compressed air it may have a lot more water vapor in it. Why? The compressor will retain more and more water in it daily. If that compressor hasn't been emptied and dried in weeks there will be a lot of standing water in it. Think that's odd? Go to the local petrol/gas station and see how much water vapor runs out of the nozzle in spray form. That's what you are inflating your tires with.

Why is this a problem? Water vapor can produce pressure spikes of 10-12 psi when hot giving you a completely false reading. I've seen this at Nationals, Club racing etc so taking control of your air source is critical in making sure carcass temps are true readings not influenced by water vapor content.

Before you get air from a third party source, ask them when their compressor was last emptied out of air and drained completely. Ask them if they have a water separator in line and check to see how full it is. Finally blow air out of the nozzle to see how much water vapor is visually present.

Dry air:
Best source for that is a scuba diving shop. You need to buy your own tank and regulator, but the air is high quality for obvious reasons. Is it worth the investment? For the street, perhaps not. For track days and racing most certainly but that's an individual choice that everyone must make. The question of the moment is how quickly can the investment pay off? If you ruin a tire in 2 sessions at $300, it already paid for itself. The downside is that you have to check the tank regularly and top it off which means a little planning prior to the track day or race weekend.

Serious racers all use nitrogen as it is an inert gas. That means minimal pressure gains from cold to hot of 2-3psi. Right away you immediately ask the question "What pressure do I start with?" and that of course is all based on a slew of variables. The correct answer is based on pressure and carcass temps, so you have quite a bit of work to do in R&D to find out what pressure gets the carcass to correct temps for that rider, that day, that track time, that lap time, that tire carcass and compound.

Given what you learned here, how will you apply this knowledge? Is it worth the effort to make the investment of time, energy and some cash or are you happy to stay where you are with the system and or source you use?

Does it hurt to ask if the dealership or tire vendor if they emptied the compressor yesterday or this week? No it does not, and those who care do it regularly.

Tires are our biggest consumable item, so wouldn't it be worth the effort to get the best return on investment? Race tires last a couple of hundred miles/kilometers so for me, it is worth it all. Why? Optimal carcass temps give maximum grip and wear. My tire bill would be 5 times what it is now if I didn't take a few extra minutes to pay attention to the tire carcass temps and wear and all the tire test data at feelthetrack.com supports this.

Thanks for reading and pass this along by sharing to your rider groups, email lists and forums and our community will thank you for sharing!

Always On Mod
1,844 Posts
Discussion Starter #4 (Edited)
If there's one post from this week that needs to be shared universally it is this one. With 5,000+ reads on the last post and 58 shares, perhaps we can up the percentage to 30% this time or more? We have a heavy street focus here, so that is by far the majority of riders in our community and the information here works for EVERY category of street bike.

Day 3: Carcass dynamics

Have you ever sat on the tire you are buying to see if the carcass will hold your body weight?

Have you ever pushed on the tire to see how it will flex?

Have you ever pulled on the sidewalls to see how much they will deflect?

Have you ever measured the new tires circumference once it is fully inflated?

Have you ever mixed brands between front and rear tires?

Street/road tires
Are built generally for durability and therefore longevity. They are normally one compound across the entire upper surface. Tires are generally fairly robust in terms of carcass rigidity to meet those goals and pressures generally reflect that design. There are a range of pressures of course for obvious reasons: - compare at BT016 to an Avon Touring tire and it makes sense IF you feel the way the tire flexes.

Hypersport tires
Are constructed for a specific purpose and have hard carcass center and a softer outside edge of various measurements in width. That means the tire will flex one way with the hard center, then flex differently when on the side/softer compound. That creates different levels of flex and feel and as a rider you need to be prepared to experience that. Were you aware of this?

Track tires
Are built specifically for this purpose and are usually one compound across the upper surface. They come in several compound types from soft to endurance. Some have numbers, some have letters to designate the compound. All brands feature different carcass designs, so the feel from the tires will be dramatically different based on carcass rigidity, sidewall flex, pressures required etc. These tires can be DOT with sipes or slicks and therefore can offer very different levels of feel and flex based on the manufacturers carcass design.

So how many of you have spooned on a new set of tires, then gone off for a blast with no consideration for what you bought, how it feels/works and what the pressures need to be and with no consideration for geometry effects based on changed tire circumferences? #$%^&&$#^ !!!!!!!!!

Stop here and read these tire test reports and watch the videos. Everything that follows will be based on this material.



Tire circumference
If there was a 25mm difference in circumference just on the rear tire how would that affect the handling of the bike? Add in the difference on the front tire at 10mm, is the effect profound? Is it worth knowing this information BEFORE you take off and ride hard? If you don't know, the best result is you complain about the tires, the worst is you crash and have no idea why. In both instances you need a good slap across the back of the head or a derivitive thereof from your peers or what would be acceptable in your country! Not only did you massively increase your chances of being hurt but worse, you put others around you and on that road at risk. I'm heartily sick of this behavior because of the above. As the phrase goes "Free your mind" and start being much more serious in this area as of right now. It will make the bike handle much better and possibly save yours or anothers life.

If tire circumferences are drastically different, you can move the forks in the triple clamps/yokes to get some level of correction by raising or lowering the front end. if you are fortunate, you may be able to do the same to the rear end with shock ride height through spacers or shock adjustment.
Is there a mathematical formula that works every time? NO....... It's your bike and has to meet your needs, and the tires you put on will have a different roll profile, surface and sidewall flex so YOU have to experiment to find what you need. Yes, I know it is tedious, but trust me it is worth every second when you get to the pay back. Max grip, optimal wear. I'm just sayin'.......

Have you noticed that sipes/tread patterns on Hypersport and race DOT tires are getting smaller and never reach the edge of the tire? The design of these sipes is a critical engineering factor in controlling flex, so it is not a unique brand identifier designed by the marketing department!

Now think about wet weather riding with this sipe design - flaws? Spirited street and track riding - benefits? Brand differences - go look online!

DOT race tires have a significant amount of engineering put into this sipe design, so read up on why the sipes are the way they are. That will give you some hints as to how the tire will behave which can be matched to the carcass structure. Again, invaluable information.

Slicks offer the most amount of grip of all tires as there is no sipe pattern. If that is true, how does that impact the chassis and suspension on a track or race bike? Hint - read all the other tire tests I have posted at feelthetrack.com under product testing.......

This topic is the one I am most passionate about because the risk factor is so high especially for street/road/touring riders.

1. Feel the carcass of the tire you are buying
2. Measure the circumference when fully inflated
3. Store that data
4. Correct your chassis geometry based on the differences
5. Ride at 80% to feel the difference with that carcass
6. Find the cold or hot pressure you need
7. For track tires, that pressure is that day only
8. Stay with the same tire for a season or more!
9. If you change tires even within the same brand, start at 1

Always On Mod
1,844 Posts
Discussion Starter #5 (Edited)
Day 4: tire pressure affecting chassis balance

No need to preach about carcass temps but let's take a closer look at the effects of pressure on the carcass. The cold pressure will ideally grow 5-7psi while on the track or 3-5psi on the street. What does that growth do to the contact patch size? How does that affect rake and trail and weight transfer?

Small bikes (GP250, 400, 650 twins) use very high corner speed and therefore load the outside and sidewall tire heavily throughout the corner.
600's use heavier trail braking going in and high corner speed.
1000's brake hard going in, minimize mid corner and hammer the throttle going out.
All of this behavior radically changes the carcass shape and therefore air pressure is a vital factor in controlling sidewall and upper surface flex.

Generally you use more air in a soft carcass to maintain structural shape under heavy braking and acceleration, or you use less air pressure to increase the size of the contact patch and therefore tire surface and grip. Depending on the bike and riding style there are g-load needs to be met as well as braking and accelerating forces. What pressures are you running, but more importantly, WHY? Have you gone through a range of pressures to find the pressure that gets the right carcass heat range and gives you the correct carcass flex/stability you are looking for?

For example, in the previous generation Pirelli DSC1 DOT race tires I ran 38 hot front and 33 hot rear on my VFR400 race bike. That gave me the structural roll profile I needed going into the corner and the sidewall rigidity I wanted for very high speed mid corner stability. It took me 3 days of testing to get to that point but it took my lap times down to race pace and most important of all I was comfortable and trusted the tires. I got the tire to meet MY needs. Your needs may be completely different.

Why so high in the front? Let's look at this dynamically. Hard braking produces weight transfer, That loads the tire and creates carcass flex. If the sidewall flexes too much, two things happen:- you lose tire shape and therefore some degree of steering ability from the profile loss AND you lose rake and trail numbers substantially enhancing that loss of steering. Take a second to stop right here and visualize that in sequence as braking occurs.

We can manage brake pressure to deal with this, but should we have to do that on the street or track? If we do, the bike is managing us. That's very poor attention to this part of set up. The bike should do exactly what you want it to and that is why carcass flex/tire pressure is absolutely critical with soft carcass tires. How many street crashes are related to not checking tire pressure before going riding and the tire folding under braking? How about crashes on the track from poor/excessive tire wear at the track from incorrect pressure?

Stresses under acceleration are obviously very different by engine size, configuration and torque/peak power. Again sidewall flex has the same roll to play as does pressure in controlling flex. If the sidewall flexes too much, can you control you exit line from any corner street or track? Where will you ultimately go exiting a corner (and as a result, what do you do with the throttle?). Now stop reading, visualize that scenario step by step starting with brake release and throttle roll on.

Now add in weight transfer and the effect on the front end geometry.

As you have those mental frame by frame references in place, when you change brands of tires you need to understand what degree of flex you have to manage (this builds on yesterdays post) and therefore the tire pressure that YOU need.

We are all different riders in so many ways no matter what we ride, where we ride and how we ride, and tire carcasses are as different as we are. If you understand flex and pressure working together, you can tune the tire to get what YOU need out of it. That in and as of itself is priceless as we all know how small that contact patch is, so why not get the best out of it but more importantly, get the most out of the rest of the tire?

Always On Mod
1,844 Posts
Discussion Starter #6 (Edited)
This will be the last posting for the week on this topic. It has been a very comprehensive coverage of the basics without getting too technical, but sufficiently detailed to allow you to take this technical knowledge with you to your street, track or race bike. A personal thank you to everyone that took the time and good conscience to cut and paste the information into forums globally for the benefit of our community at large, so here’s the last one for you to copy and paste. Realize there is a lot more documentation and a wealth of video at my www.feelthetrack.com and come back every week to my Facebook page: davemosstuning so that the learning can continue and you can debate and answer the Friday questions.

Whenever I go through this exercise be it a seminar, tuning event, track day or race weekend, I challenge all those riders that receive my help to find another that needs it and to pass on what they learned. There are millions of riders that need this help so if we all find one rider, then that rider finds another, slowly but surely you can help me fulfill my daily mission to educate our community and save lives!

Consider yourself challenged with the gauntlet thrown down – go find a rider that needs the help and pass the challenge on! And ……. there’s one more request at the end of the article!

Day 5: Assessing tire wear.

By now you have realized that tires are a key element in chassis and suspension tuning, and from that perspective lets see how tires help us recognize wear patterns that can guide us to the correct chassis or suspension solution.

For street riding, it is very unusual to see poor tire wear based on poor tire pressure. The most common is the ubiquitous ‘flat spot’ on the rear followed by the one side worn out more than the other on a front tire, also from low pressure and crowning of the road. It may be the left or the right side, depending on which side of the road you are forced to drive on in your country!

More commonly with street tires, wear patterns reflect suspension set up most noticeably with rebound damping. Lets start with the rear tire as that is the easiest to look at. When you follow the direction of rotation of the tire and on the outside edge of the tire, you will see the first or leading edge of the tread/sipe rounded down or gone completely. Why?

Lets break this down:
- you are braking and turning, so given weight transfer, where is the chassis load being placed?
- that being said, how much load is on the rear tire?
- if there’s a limited load on the rear tire, how much load is on the rear shock?
- given this load, how does the tire react to every little surface irregularity?
- are you seeing why the leading sipe is wearing down so fast?
- think about deflection and flex (there’s a groove behind the first edge)

If you move further toward the middle of the tire, you might notice that this rounding effect switches sides and moves to the rear edge of the sipe. ??!!??

Go on – go look at your rear tire to see if this is the case…… yes, now ☺

In the middle 2/3rds or perhaps ¾ of the carcass you have control of the rear tire via the throttle, therefore the rear tire and rear shock are under load. What degree of load depends on many factors (tire pressure, shock settings, gearing, torque, peak power, throttle position and roll on, 1 or 2 passengers, rear axle location etc). With this load on the swing arm, shock and tire, the carcass flex will be completely different in every aspect from braking and turning.

With that being said, on the outside edge of the tire under braking and turning, how fast is the tire reacting to every bump it encounters. When loaded, is that reaction speed different? Why?

Welcome to the world of high and low speed damping, all managed via piston design, flow rates, valving shims and oil viscosity. That’s why suspension experts and companies take so much time with this level of engineering to provide you with better alternatives to stock components but we cannot digress in this post.

You will see in EVERY stock motorcycle this form of tire wear. Don’t bitch about it – you get an enormous amount of engineering in modern bikes – learn how to tune the suspension to optimize the tire wear.

You only tune the tire where you have control of it via the throttle or brakes as you have no control over high speed damping!

Track and race DOT and slick tires:
Because these tires are subjected to a significant amount of load well above and beyond street bikes, these tires tend to show you all kinds of wear patterns in very short order ie: 5 laps/10-15 miles (bear in mind that they are meant to last a few hundred miles, not thousands!).

With DOT race tires, you can see the above sipe rebound markings clear as day, so you can make corrections to rebound damping to a degree, but it will never be perfect. Why not – we are not binary robots that do the same things every lap in every detail. Good luck on that quest…….

Here are the most common wear patterns that I deal with!

Should you get the hot pressure wrong, you will experience two things:
- when the pressure gain is 3psi or less or the carcass is at 120F, the carcass cannot get to operating temps so it tears itself apart creating the classic “cold tear

When the pressure gain is 8psi or more and the carcass is over 200F the carcass is over heating creating the classic “hot tear” This is very easy to diagnose with a pyrometer probe and less accurate with a pressure gauge.

You have to let the tire go cold and reset the cold pressure, then start over, or you stay in the hot pit chasing carcass temps for far too long!

Do you have the right compound?
If you have the wrong compound it will tear itself apart in 3 sessions, so do your homework and contact the tire vendors that frequently travel to that track to get their advice. They don’t want to ruin their reputation by selling you the wrong tire – they want you to have a great experience on their product so you will buy it again. Phone call, email, local racer comments – research them all.

Track temperatures and compounds
You have to understand by brand why each compound has a heat range that it works best with. For the most part, soft tires need hot track temps of 100-120F or more. If those temps are not present, DO NOT use that tire. A medium range compound tire is much more durable and will generally work much better in the 50-80F range. Obviously hard tires need heat but they have only so much grip as they are meant to be endurance type tires capable of sustaining 1-2 hours of track speed so that carcass has a design principle embedded into its construction. Does every tire work the same way in each brand? No it does not. Ask you vendor, top club or national racers, or other riders that know this information.

Tire carcass designs change regularly so what was true one year is upside down the next.

If there’s too much or too little weight bias on the rear tire you will get a band of wear that resembles a cold tear. Your pyrometer probe will give you immediate clues as to why the tear is there. Too little heat, the rear end is too high – too much heat there’s too much weight on the tire. Remember, nothing is black and white, so you need to recheck sag and hydraulic settings!

If the edge of the front tire looks like it lost the fight to a cheese grater, you have a geometry tear from too much or too little weight on the tire. Your pyrometer probe will give you immediate clues as to why the tear is there. Too little heat, the front end is too high – too much heat there’s too much weight on the tire. Again, remember that nothing is black and white, so you need to recheck sag and hydraulic settings!

Ustream shows:
Tires: - http://www.ustream.tv/recorded/6189441
Tire wear:- http://www.ustream.tv/recorded/6516891

At the start of the week, I said I would ask for donations for all the information I provided to you based on experience I gained from 1995 through a lot of hard work. This is the way I make my living and I know that for everyone that read these posts, there was some very useful information to them that can save them hundreds if not more on tire bills alone, never mind improving the handling of the bike.

It seems fair to me to ask for $5 from anyone that found this information useful and helpful. The donation can be made via PayPal using [email protected] and please mention Tire Tech in the message box. If you’d like to give more, that would be appreciated but this is an individual choice. If you don’t have PayPal you will have a friend or fellow rider that does!

If you want to mail a check, please send it to Dave Moss, 1445B South 50th St, Richmond CA 94804

My sincere thanks in advance to all those who donate(d). The revenue will allow me to keep going, produce more videos and tech articles for our community and continue on my quest to help every rider out there.

Please share with the forums and web sites you placed the tire tech on so everyone can debate this and come up with their solution.

You have bought tires that have a stiff sidewall but soft carcass top to the tire with the same size as the ones you removed. These will be going on your street bike that also doubles as a track time at times throughout your riding season. Organize this list into the correct sequence of events:

1. Fork height
2. Setting sag
3. Cold tire pressure
4. Chain tension
5. Shock length
6. Adjusting hydraulics
7. Hot tire pressures
8. Track geometry amendment
9. Circumference measurement
10. Track hot pressures

Chairman of the Board
16,056 Posts
Good post man. I love Dave and I have his site bookmarked on all my computers. Subscribed.

235 Posts

971 Posts
Is it just me, or does the R1 he's riding, not sound like a cross-plane engine and more like a normal inline four?

Always On Mod
1,844 Posts
Discussion Starter #18
Day 5 updated

I think his R1 sounds like a normal inline 4 because he keeps it pretty high in the revs, along with the video quality it makes it hard to distinguish. It's easier to hear when you're out on the track and he goes by you :spit:
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