2018-2020 Tyres Thread

[Mike_s]

There's definately coring, I've seen pieces of it at Virgin and Mclaren - there's usually a sample area laid out when a track is resurfaced. I know for sure mclaren take samples of the laid down rubber layer as well as marbles every time they go somewhere too.

I don't know who's testing road tyres on a steel drum but given some manufacturers it wouldn't surprise me too much , however road tyres tend to be validated over thousands of hours of actual on vehicle testing over various surfaces anyway.

When you purchase a (road) tyre there are ratings for the tyre on various criteria. The rolling resistance testing is conducted using a steel drum, which is repeatable and reproducible, but not really anything like what happens in real life.
Of course it is the case that tyres are tested in the real world also, but the point I wanted to make is that what is actually happening at the interface of the tyre and the pavement is very poorly understood.
Martin Brundle often talks about 'oils' coming out from the surface, which is complete nonsense... nothing comes out from the pavement, unless something awful has happened. What is clear is that for a new surface the aggregate is covered in binder, therefore the tyre is rolling on a film of binder... this is why newly resurfaced tracks are often low grip. After a period the surface layer of binder wears away and the tyre 'sees' the microtexture of the aggregate, so grip levels change as the surface ages.
F1 tyres are not similar to road tyres in most respects, but from the engineering perspective it is important to understand at different length scales, from centimeters to nanometres, how the tyre and the pavement interact. This is not well understood by anyone at present, which is bizarre given how important it is to performance.

[PhillipM]

The ratings from the steel drum tests are just that though, ratings, regulated by governments, that have very little application in the real world and they're not used for tyre development.

They're there so that the 99.9% sheep stop buying tyres made out of remoulded bakelite slapped over a 30 year old carcass.

[JordanMugen]

The ratings from the steel drum tests are just that though, ratings, regulated by governments, that have very little application in the real world and they're not used for tyre development.

Do you think the Advan A052, Falken RT660, or Potenza RE71-RS are really 200-treadwear "street" tyres or are they autocross-cheaters and the idea of a street tyre that gets heat cycled when you drive on them (as these do!) is ridiculous?

I'm planning to go for to the Hankook RS-4 myself, as it seems like more of a "genuine" street tyre, so hopefully it will last longer even though it's much cheaper. Currently have the Advan AD08R on there, which is very much a street tyre and seems quite durable.

[godlameroso]

The ratings from the steel drum tests are just that though, ratings, regulated by governments, that have very little application in the real world and they're not used for tyre development.

Do you think the Advan A052, Falken RT660, or Potenza RE71-RS are really 200-treadwear "street" tyres or are they autocross-cheaters and the idea of a street tyre that gets heat cycled when you drive on them (as these do!) is ridiculous?

I'm planning to go for to the Hankook RS-4 myself, as it seems like more of a "genuine" street tyre, so hopefully it will last longer even though it's much cheaper. Currently have the Advan AD08R on there, which is very much a street tyre and seems quite durable.

They all last the same, about 8k miles on the driven axle. The RS-4 is a great endurance tire, for me though, the new king is the Kumho V730, which is the Viper ACR tire but updated. It no longer delaminates like the V720, and has excellent grip, and unlike the crappy F1 pirelli's the sidewall is very strong and likes low pressures. It's a great tire especially if you're camber limited.

The Advans, the RE-71's(which are being discontinued), are very consistent with temperature. The Falken gets greasy, you have to manage temperatures and pressures. Modern track day tires are more pressure sensitive than temperature sensitive. The Federal RSR-RR is a great tire if you can manage the temperatures and pressures.

All 200tw tires are loud, because they run low tire pressures and have stiff sidewalls they ride nice, but they sound like you have mud tires on. There's a constant hum mixed with a bag of rocks sound, it sounds like a bad wheel bearing.

[BassVirolla]

Speaking about Baku tire failures in the Red Bull team thread:

Let's think about this. The changes that Pirelli made to the tire are on the tread because the tread was delaminating correct? They added an extra kg on the outer part of the tire, the part of the tire that spins the fastest. The blow outs happened at high sustained speed. All the failures were the same torn sidewall. If you add more mass to the outside of a spinning object, that mass gets multiplied due to centrifugal force.

What if Pirelli when considering to strengthen the sidewall along with the increased mass of the tread said, "nah It'll be fine". Would this lead to more force stretching the sidewall and possibly tearing it at speed?

How would low pressure affect this?

Just throwing it out there for discussion's sake.

Probably lower pressures drive to a increase in the difference between low speed and high speed behaviour / shape.

And lower pressures, by means of increased dynamic deformations, generate higher temperature in the carcass / sidewalls. Is common knowledge that most blowouts in road tires come from low pressure causing overheating, delaminating the tire.

Possibly Pirelli doesn't dare to increase more the lower pressure limit, because that will cause lots of performance lost.
Will be very hard to reach the tire temperatures, and the dynamic compliance / suspension / dampening will also be reduced.

I think Pirelli put themselves between a rock and a hard place with these tires and the limits in pressure and camber...

[godlameroso]

Speaking about Baku tire failures in the Red Bull team thread:

Let's think about this. The changes that Pirelli made to the tire are on the tread because the tread was delaminating correct? They added an extra kg on the outer part of the tire, the part of the tire that spins the fastest. The blow outs happened at high sustained speed. All the failures were the same torn sidewall. If you add more mass to the outside of a spinning object, that mass gets multiplied due to centrifugal force.

What if Pirelli when considering to strengthen the sidewall along with the increased mass of the tread said, "nah It'll be fine". Would this lead to more force stretching the sidewall and possibly tearing it at speed?

How would low pressure affect this?

Just throwing it out there for discussion's sake.

Probably lower pressures drive to a increase in the difference between low speed and high speed behaviour / shape.

And lower pressures, by means of increased dynamic deformations, generate higher temperature in the carcass / sidewalls. Is common knowledge that most blowouts in road tires come from low pressure causing overheating, delaminating the tire.

Possibly Pirelli doesn't dare to increase more the lower pressure limit, because that will cause lots of performance lost.
Will be very hard to reach the tire temperatures, and the dynamic compliance / suspension / dampening will also be reduced.

I think Pirelli put themselves between a rock and a hard place with these tires and the limits in pressure and camber...

Good point, the tire may be straddling the line of being squished and stretched as the speed of the track changed. The repeated stretching and squishing due to the low pressure compromised the sidewall. Therefore the fix would be to strengthen the sidewall, however that would further increase the mass of the tire.

Sort of like folding a piece of paper over and over, then a crease is created, which becomes a rupture point.

[Hoffman900]

Interesting take and insinutes that RedBull might have been pushing things a little...
https://www.racefans.net/2021/06/15/ext ... -in-spain/

I’m sure that sly dig at RedBull will be enough to make some of the poster’s here explode

[JordanMugen]

Speaking about Baku tire failures in the Red Bull team thread:

Let's think about this. The changes that Pirelli made to the tire are on the tread because the tread was delaminating correct? They added an extra kg on the outer part of the tire, the part of the tire that spins the fastest. The blow outs happened at high sustained speed. All the failures were the same torn sidewall. If you add more mass to the outside of a spinning object, that mass gets multiplied due to centrifugal force.

What if Pirelli when considering to strengthen the sidewall along with the increased mass of the tread said, "nah It'll be fine". Would this lead to more force stretching the sidewall and possibly tearing it at speed?

How would low pressure affect this?

Just throwing it out there for discussion's sake.

Probably lower pressures drive to a increase in the difference between low speed and high speed behaviour / shape.

And lower pressures, by means of increased dynamic deformations, generate higher temperature in the carcass / sidewalls. Is common knowledge that most blowouts in road tires come from low pressure causing overheating, delaminating the tire.

Possibly Pirelli doesn't dare to increase more the lower pressure limit, because that will cause lots of performance lost.
Will be very hard to reach the tire temperatures, and the dynamic compliance / suspension / dampening will also be reduced.

I think Pirelli put themselves between a rock and a hard place with these tires and the limits in pressure and camber...

Good point, the tire may be straddling the line of being squished and stretched as the speed of the track changed. The repeated stretching and squishing due to the low pressure compromised the sidewall. Therefore the fix would be to strengthen the sidewall, however that would further increase the mass of the tire.

Sort of like folding a piece of paper over and over, then a crease is created, which becomes a rupture point.

Did Pirelli not increase the sidewall stiffness/strength with these 2021 tyres? I guess they didn't, but that's quite surprising.

the new king is the Kumho V730

Nice! The tread pattern looks like aquaplane city, it seems shocking that is supposed to be a road tyre!

[godlameroso]

Pirelli made the tread stronger so it wouldn't delaminate. This added mass to the tread. They made no mention about the sidewall

730s are fine as long as you drive straight in the rain.

[Wouter]

https://www.astonmartinf1.com/en-GB/art ... mStatement

"Following the tyre issue on Lance Stroll’s car on lap 29 of the Azerbaijan Grand Prix, we have worked with the FIA and Pirelli during their investigation.

"We can confirm there was no car fault that caused the tyre to fail.

"The team has always operated its tyres within the Pirelli prescribed parameters and will continue to do so."

[Hoffman900]

Classic PR moves from all of them.

“Just for the record, and to answer the question no one asked, we did not do that thing that no one accused us of doing”.

I think the real truth is there is likely some blame to go around; from Pirelli, the FIA, and the teams.

[godlameroso]

Regardless of the blame the grand prix is this weekend, we don't want a repeat of that happening. I feel it's unlikely because the nature of the track will maintain tire pressures in a window.

I believe that the nature of the Baku track with the hard tires meant they would fall out of their temperature window, and thus the pressure would decrease, and would fall back into the window in the high speed sections. Therefore the pressure was changing drastically throughout the tire stint. In sectors 1 and 2 the tires would cool off because little energy is going through them, then towards the end of sector 2 and through sector 3 the tires would heat up. Repeat this for 30 times, and you're bound to get inside sidewall failures if the tire deflates enough in the slow speed stuff. There's 4 slow speed right hand turns in sectors 1 & 2, that rear left doesn't see much of anything and then it's full on high speed with low tire pressure.

In Paul Ricard there are constant turns and energy is constantly going through the tires with only a few sections for them to cool off so tire operation will be in a narrower window. In my opinion this shouldn't happen in the next race.

The measures by Pirelli are a bit half arsed.

[RZS10]

Suggestion: change the name of the thread to reflect that it's still relevant to the current 2021 tyres.

[godlameroso]

Suggestion: change the name of the thread to reflect that it's still relevant to the current 2021 tyres.

Low pressure would cause more flex in the sidewall. Would that alone be enough to cause a tear in the tire in so many different cars? Is this issue track dependent where the tires are falling out of their intended pressure due to the low energy corners?

Are there any other circuits on the calendar?

[RZS10]

Suggestion: change the name of the thread to reflect that it's still relevant to the current 2021 tyres.

[...]
Are there any other circuits on the calendar?

There's 20 other circuits on the calendar.

But in all honesty ... why did you quote that post when what you wrote had absolutely nothing to do with it?