Race tyre experiences

[Tack Reacher]

Just BTW, at the last race meeting I was talking to a guy who runs pirelli's on his bike (non KTM) and he was saying that he wasn't happy with his previous suspension guy so he changed to another professional suspension guy. The new guy changed quite a few things ( wouldn't say what...I think springs mainly though) and the bike was 1.5 secs off his PB. Normally the guy is a front runner. The point is that even though they went the wrong direction it doesn't mean the new suspension guy is stupid or bad but possibly didn't understand the tyres and their characteristics properly.

Sometimes you learn more from what's going wrong then right.

 

[Tack Reacher]

good article from box repsol

Temperature and asphalt: key factors when choosing a tyre
In every Grand Prix, tyre technicians working for Michelin, the official MotoGP World Championship provider, can be seen measuring the temperature and assessing the asphalt conditions on the track. They do this for every race, to test all of the factors that influence the best choice of tyre for the teams and riders.
All MotoGP World Championship teams have a tyre technician who works for Michelin, the official tyre provider in the 2016-2017 season. The technician carries out a comprehensive analysis of the conditions at the Grand Prix, offering any necessary advice for the team and rider to be able to choose the most suitable tyre when required.
Their work and understanding of the task are crucial for the team's performance and the rider's safety. Their advice is based on an analysis of the temperature and position of the track, tyre temperature and pressure, and the rider's comments during training and the race. The professionals who work with the teams in each Grand Prix emphasise that: “the estimated temperature of the track is not the only consideration. For each race, we assess the layout of the track, including the shape and direction of turns, the micro and macro-granularity (compactness) of the surface, and the lateral and longitudinal forces applied to the tyres".
Each tyre is designed to provide the highest level of performance and sustainability within specific temperature parameters. Data analysis and the choice of tyres affect the rider's performance on the track. If the tyre overheats, it loses grip and the motorcycle begins to slide and turn. Bubbles can also appear in the rubber lining. At low temperatures, the wheel loses its full grip potential and the motorcycle begins to slide. This can cause a phenomenon called graining, where the rubber develops small ridges across the edge of the tyre.
As confirmed by Michelin technicians who work closely with the Repsol Honda Team, "temperature has a direct impact on tyre grip and sustainability". They are designed to be highly versatile, which means a consistent performance in a wide range of temperatures”.

Choice of tyre
Michelin provides a wide range of different tyre varieties at each MotoGP Grand Prix to ensure that the ideal solution is offered according to the conditions in each race. Before going to the circuit, Michelin staff work closely with member teams to assess the different possible circumstances. However, they emphasise that "tyre pressure and motorcycle adjustments help, but ultimately the riders themselves adapt most effectively to changing conditions, and can change their style at the wheel to ensure the highest output from the tyres in order to achieve the best results".
The choice of tyres for the front and back wheels depends on both the team and rider, and in most races they make the correct decision, since all of the tyres provided by Michelin are adapted to the track and range of temperatures. The team's experience and the advice from Michelin technicians let the riders focus on their performance on the track, although depending on their position on the grid and qualifying requirements they can also have the last word on the decision, as confirmed by the Michelin experts: "When there are changing circumstances, some pilots decide to try a more aggressive strategy with the choice of tyres, using different designs to their opponents. If they do this, they need to adapt their style to achieve a higher level of performance and sustainability from the tyres".

 

[Tack Reacher]

the information is out there if you look

MotoGP: Riders And TiresTires need heat, without which everything fails

.By Kevin CameronGold & Goose October 17, 2014

Changes in tires are not only driven by changes in rubber and construction technology but also by what riders need and want from tires.Back in 2002 at the beginning of MotoGP, Valentino Rossi said this about two/four-stroke differences relating to tires: “With the four-strokes, there is a close relationship between the throttle and the back tire, so when we accelerate a little we are already giving power to the rear rubber. With the new bike, you can accelerate when you are leaning tightly, which wasn’t the case with the 500, where you had to raise the bike to be able to open the throttle.”This difference came from the contrasting ways two-strokes and four-strokes came on throttle. With two-strokes, on closed throttle, the cylinders filled with exhaust, and as the rider moves the throttle, the small amount of fresh charge is so diluted in the cylinder that it cannot fire. As the throttle opens more and more, this becomes less true. The Honda NSR500 used to give two loud pops (from the ignition of mixture accumulated in the pipes) and then kick the rear wheel sideways as the engine reached a state in which it could fire. To have the grip to handle this sudden torque, the rider “had to raise the bike.”

In 1978, this engine characteristic allowed Kenny Roberts to apply his dirt-track experience to 500cc Grand Prix roadracing. He would get the bike turned early on a tight radius, then lift it up to plant it on bigger tire footprints, and use the rest of the turn as a curved drag strip of increasing radius. This style confounded riders raised on the classic “big line” of maximum radius. Using all of their tire grip for turning, they could not apply throttle, and thus could not accelerate. Roberts, while slower at his apex, was able by raising the bike to begin accelerating earlier so his exit speed was greater than that of the big liners. This is the style people would soon call “point and shoot.”

Because four-stroke engines have their strokes separated by mechanical valves, they avoid two-stroke exhaust gas dilution. So as soon as the rider moves the throttle, the engine begins to fire, giving a very small amount of power. This is “the close relationship between the throttle and the back tire” of which Rossi spoke. This made the defensive point-and-shoot riding style unnecessary, so GP riders advancing from 125/250cc GP classes no longer had to forget everything they had learned to adapt to big bikes. In 125, there is too little power to make up a large loss of speed in corners, making high corner speed essential to good lap times. This was also true in 250, which is why in the 500 era we saw some 250 riders fail to fully make the transition to 500. Riders cannot just change their styles because it is a good idea; style is the complex set of reflex loops that are the only safety the rider has. Changing them would be like learning to walk all over again.Tires began to be built, not for the spinning and sliding of point and shoot, but for an emerging combination of 125/250 corner speed and smooth four-stroke acceleration. Michelins were not noted for edge grip in the last years of the 500s, for it was observed that “the tire with the best edge grip is not the tire that will push the bike ahead.”When Bridgestone began development of tires for MotoGP, riders likened them to soft qualifiers—“good in the first corner but by the next corner, it’s down to zero.” Rider Makoto Tamada showed their fast-improving qualities in 2004, but in that season, people referred to cool mornings as “Bridgestone weather” because their still-very-soft tires were at their best before the heat of the day.

Michelin, meanwhile, found it had to increase carcass stiffness to support the new, heavier four-strokes through long, high-lean cornering. At the same time, to gain traction for acceleration, Michelin reduced inflation pressure from a previous norm of 1.9 bar (27.6 psi) to a low 1.5 bar (21.8 psi)

Illustrating the contrast of styles at the time, Valentino Rossi needed a stiff carcass that could take prolonged high-lean-angle cornering, but then-teammate Colin Edwards wanted a flexier carcass to spread out the footprint he needed for the traction to accelerate. If he tried to use Edwards’ carcass style, Rossi said his bike would jump sideways in turns as the soft carcass buckled under high side load

Bridgestone attacked its warm-weather problem and came up with rubber that somehow combined softness necessary for grip with tensile strength and abrasion resistance necessary for durability.

New or very adaptable riders were able to make themselves open the throttle at full cornering lean angle. Working the tire in this way, Casey Stoner could get his tires working quickly and keep them hot enough to grip. Others were less fortunate. At Mazda Raceway Laguna Seca in 2008, Edwards found himself all the way at the soft end of Michelin’s range with no place to go. He could get the tire to 115 degrees Centigrade but it needed 130-135 C to work. He reduced pressure, hoping increased flex would heat it up. Nothing. He tried overinflating. Again, nothing.

When I asked Pirelli race engineer Giorgio Barbier why riders like Carlos Checa and Marco Melandri were having to leave MotoGP, he said he believed these men were unable to make themselves go against everything in their experience and use more throttle at full lean. But without working the tire that way, effective operational temperature could not be reached. Without grip, racing was impossible. Off to World Superbike, where the older style can still work.Today we see Marc Marquez and Dani Pedrosa looking as if they are riding a corner-speed style until you compare it with Lorenzo’s big line. Then it’s clear that the Honda men are turning most quickly near the apex (where elbows touch pavement), revealing what Cal Crutchlow calls “the V-shaped Honda line.” After that phase, they lift their machines up and use the remaining part of the corner for acceleration. Yet to keep the tires hot, they must apply throttle at high lean angle. When it all works as it should, they are unbeatable, just as so often was Kenny Roberts.

 

[Tack Reacher]

[url]https://youtu.be/lhKybNL_Fv0



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[Tack Reacher]

For those interested a team I have been helping out just did a test day comparing the pirelli 150/60 SC1 to the Pirelli 140/70 SC2.

The track is not very long and has a very open pebble surface (so not high grip and its not a high load track either) and track temp was only 32 degree Celsius.

The first very obvious difference is that the SC2 has a much stiffer carcass. I fitted the tyre to the rim and the difference was very noticeable.The other interesting difference was that the 150/60 tyre on the 4 in rim gets pulled in at the bead and the last 5mm of each edge barely touches the ground whereas the 140 uses the whole footprint right to the edge. The actual "usable" footprint of each tyre is 175mm from edge to edge so there is no gain by running the 150/60 on a 4in rim. Possibly, a wider rim will change the carcass shape and allow full tread use. The durometer reading showed that the 150/60 was 58.5 Ha and the 140/70 showed 57.5 Ha at ambient temps. However I didn't compare at 80 degrees celcius for comparison...sorry.

After spending the first half of the day getting the rider tuned and circulating within 0.2 sec of each other and getting the track pressures correct as per Pirelli specs (not the warmer temps), we concentrated on tuning the suspension to get the tyres working properly and making final adjustments.

We then blind tested the tyres without disclosing lap times to the rider.

End result was that the 140/70 was 0.7 secs faster than the 150/60 and was the fastest supersport time set at this track. The rider felt that he could lean further on the 140 (which the speedangle confirmed) plus he said they felt much better mid corner (as in more edge grip).

The disclaimer to all this is obviously that this was the result from this test, at this track, on this surface, with this rider, with his suspension and set up and at that ambient/track temperature. You need to test the same way at your track on your bike in your conditions to reach a conclusion and keep in mind that results will vary depending on atmospheric conditions even at the same track...eg. temperature and UV dust previous rain events etc. And yes, your right it's not easy or cheap. But that's the point...attention to detail and a clinical approach is a better way to improve then hearsay and opinion.

 

[John390]

great stuff Tack. I mean, really great. Especially for a new guy like me.

I used to follow motoGP back in the day, and while I didn't know why, I could see the different styles of line between some of the riders and could see how they were effective.

 

[Tack Reacher]

great stuff Tack. I mean, really great. Especially for a new guy like me.

I used to follow motoGP back in the day, and while I didn't know why, I could see the different styles of line between some of the riders and could see how they were effective.

there is plenty of good info out there John when you're watching closely.

The interesting thing was that before we went up for the tyre test mentioned above i took some scales around and we weighed the bike with rider, without rider, increased preload right thru to no preload, weight entirely on the pegs and weight on the seat in different positions, fuel etc etc. what the exercise highlighted was just how much the riders weight changed the weight bias by moving quite small amounts on the seat. the main reason was the affect on centre of gravity. Unfortunately most people don't have any idea of the weight distribution with or without a rider.

 

[John390]

Oh, I don't know exact numbers, except my own weight with my gear on, but I totally get weight transfer. its more pronounced on a bike than in a car. Hell, all you have to do is watch the headlight when you brake or hit the throttle. or just move around on the pegs.

I'm learning by experimenting on this very thing. Weight on the left side, right side, hands, pegs, seat etc. In various situations. Of course I am not pushing the bike to its limits, because I don't want to toss a brand new bike into the weeds, or under a car etc

 

[Tack Reacher]

just for example we simulated start position weight. we tried all sorts of different techniques including dirt track stances and the one that put the most weight on the front was chest on the tank. You should have seen this kids starts. He was beating 600cc bikes to the first corner every race and holding them out till they hit long straights.

 

[John390]

that's awesome. wow!

 

[Tack Reacher]

last year i put a talented young guy on my zx10r to race in the state road race championship. this kid has spent his whole life racing bikes with NO suspension adjustment. this kid has gotten used to using his body to make the bike do what he wants or it needs to get it around the track quickly. he holds two lap records in the 250 and 499 cc classes.

anyway. when he got on my bike with fully adjustable suspension he had no clue about how to adjust it in response to handling issues or tyre wear indications. he just man handled the bike around. he usually got 4th or 5th in these races and is about 4 secs off the lap times of bayliss who's now running the australian superbike championship on a ducati.

the thing is he was beaten by riders with equal riding ability but who know how to adjust their chassis's correctly.

 

[snaggletooth77x]

I've ran my RC390 in the OMRRA series for the last three years now. The first year I started out with the Dunlop Alpha 13's then quickly made the change to the Pirelli Supercorsa SC's due to lack of feedback from the Dunlops. I really liked the Pirellis and continued running them the next year. This year with the release of the Q3+ I switched back to Dunlop mainly for price point and also sponsorship. The Dunlops worked very well for me this year and I was able to lower my personal best laptime and help reset the lap record in ultralightweight. I'm being told as well that Dunlop will be releasing a slick next year and I'm excited to try it out.

 

[Tack Reacher]

that's interesting.

I've ran my RC390 in the OMRRA series for the last three years now. The first year I started out with the Dunlop Alpha 13's then quickly made the change to the Pirelli Supercorsa SC's due to lack of feedback from the Dunlops. I really liked the Pirellis and continued running them the next year. This year with the release of the Q3+ I switched back to Dunlop mainly for price point and also sponsorship. The Dunlops worked very well for me this year and I was able to lower my personal best laptime and help reset the lap record in ultralightweight. I'm being told as well that Dunlop will be releasing a slick next year and I'm excited to try it out.

That's great. So can I ask ...Do you run at one track only? Can you tell us what the hot mix is like on the tracks where you run? what sort of track/ambient temperature ranges do you get when racing? Are the tracks high load long duration tracks or low heat?

 

[snaggletooth77x]

OMRRA mainly runs Portland International Raceway but it can be run in two different configurations with the addition of a chicane. PIR is almost 2 miles with only 9 corners (6 right, 3 left) in the normal configuration with mostly high speed corners and not much braking. We also run The Ridge further north which is significantly different at 2.5 miles and 16 corners (8 left, 8 right) with a lot of elevation changes, lower speed corners and heavy braking. Both tracks are similar surface with a pebble like mix, fairly new and not very abrasive. The track temps can range anywhere from 60-140 degrees fahrenheit with ambient temps 50-105 I would say. This equates to multiple pressure changes and slight suspension adjustments throughout a race weekend. Hopefully this answers your questions.

 

[snaggletooth77x]

I highly doubt that Dunlop will make a slick, market it, and “hope” it works. Tire technology has moved leaps and bounds in the past few years. Possibly, and this is just that...possibly, they might know what the *^%£ they are doing when it comes to slicks since they kinda supply a couple small branches of road racing. That being MOTO3 and MOTO2. So maybe, just maybe they will bring some of those ideas into the design of the new slick for the 390 and it’s competition. I agree the alpha 13 was garbage and that made me switch to pirelli. Having rode on slicks in the past I would agree you would have to be “stupid” not to think that they would not work better than a dot race/street legal tire. It’s also very unlikely they will make a single compound slick. Even pirelli makes a couple for the 390. I think Dunlop has been around long enough to know what they are doing. I don’t think that PacMan meant anything derogatory with his comments, I’m thinking it’s highly unlikely that you yourself may have in some context phrased a sentence to a friend in that sort of fashion. I have myself, knowing that it’s somewhat of a sarcastic way, so I fail to see the fact of where he, or myself for the matter, by using the phrase, knows everything and everyone else is stupid.


But....Like I had said they make slicks for motogp and pirelli doesnÂ’t. They have plenty of real world results with slicks and positively will move that into the 390 and itÂ’s competitors.
I donÂ’t claim to know anything but I know some things

Dunlop has been developing a slick for two years now and is set to come out next year. The Q3+ was the first tire to come from this recent development but I'm being promised a slick in 2019 for the states as far as I know. I used to run their 125GP tires on my ninja 250 which worked spectacular so I'm excited to see a slick of proper size for the 390.

 

[ReidMcT]

I am interested in this thread, but also somewhat confused. I read many mentions of Pirelli SC Super Corsa tires, but I cannot find any such thing at the major online tire dealers. I can find some Super Corsa (V2 or V3) tires, but not in the 140/70 size that is frequently mentioned in this thread. At first, I thought the reference to 'SC' was shorthand for 'Super Corsa' but then I see SC as being a sub-type of Super Corsa models.

I will be sincerely thankful for an explanation of the nomenclature as well as a pointer to where these revered tires can be purchased in the USA.

Best,
Reid

 

[martr0nx]

160/17 rear tire

can i or should i use a 160 rear tire. want to convert to Q3+ Dunlops

 

[Tom]

Reid,
These guys have them in stock.
https://www.sportbiketrackgear.com/pirelli-diablo-supercorsa-sc-v2-race-rear-tires/

From my extensive 30 second google research, looks like the difference between the sc and sp is that the sp is geared more towards road use. The SP has a version 3 now, so im not sure if there is a Version 3 of the SC yet.

 

[Tom]

can i or should i use a 160 rear tire. want to convert to Q3+ Dunlops

Our factory rims are already too small for the 150 they come wrapped in. The easiest way to run a 160 would be to get a BST carbon rear wheel. Aside from the high cost there is a lot of debate about the carbon fiber failing in different ways. Some places might not allow them.