Avon Tires

[hsulaimon]

Does anyone have any on track experience with Avon Tires and the harder A92 compound that they are offering this year? I found very little information in the threads about Avon tires. Are they any good?

[Claude Rouelle]

How do you define a "good" tire?

Or let me ask the question a different way: If you had the luxury to have a tire company designing and manufacturing a tire specifically for your car / team, what would the specifications of this (these) tire(s) be?

This is a game that we play all year long here in our company;
- Helping tire manufacturers (racing and/or passenger) with vehicle dynamics simulation, data analysis and drivers' subjective comments to define tire force and moments characteristics which will fit a given car (that the tire manufacturer is able to effectively manufacture such tire and how quickly ... that could be another story... :))
- Helping car manufacturer(s) (racing and/or passenger) to design and/or tune a car (weight distributions, suspensions kinematics, stiffness and damping etc... ) to reach given targets such as grip, balance, control and stability.

I learnt a lot trying to get the most of imposed tires (imposed spec tires by rules) but I learnt even more by working with tire manufacturer to define a tire which fits a given car.

What I am trying to say is that even if having a tire company manufacturing specific tire(s) for you car / team is quite unlikely (Note it has been done in the past: I remember Pirelli Brazil make a specific 10 " for FEI... too bad they gave up after just one year of trying...) it is worth to think designing a tire around a car as much as designing a car around a tire: it really open your mind and it help you to choose the right tire, exploit it and know WHY you made the right (or sometimes wrong) choices.

[jlangholzj]

What I am trying to say is that even if having a tire company manufacturing specific tire(s) for you car / team is quite unlikely (Note it has been done in the past: I remember Pirelli Brazil make a specific 10 " for FEI... too bad they gave up after just one year of trying...) it is worth to think designing a tire around a car as much as designing a car around a tire: it really open your mind and it help you to choose the right tire, exploit it and know WHY you made the right (or sometimes wrong) choices.

Given most of us don't have the luxury of designing a tire around a car (and quite frankly I think there's few teams that would be able to do that effectively) we often resort to the latter! However, this is still a very intriguing topic to me as well.

At the end of my time at SoDak State's team I worked a lot with Edward and the information that Calspan delivers to us with tire data. Looking at all the different responses of tire with/rim/pressure combinations was quite fascinating to me as well! Which, to answer the original question, do you guys have access to the TTC? If not I'd strongly advise getting it. I'll have a look here and see if the A92 compound you're after is in there or not. If its a relatively "old" tire (aka, has been out for a while) then I'm assuming the answer is yes. At that point with a little help from either matlab or a program like OptimumT (which has a trial period for teams to use!!) you can find out everything you'll need about a tire.


EDIT: Upon looking it seems that round 2 was the only round that had Avon tires in it, which are the "ACB0" compound. Haven't found out a whole lot about those from a quick google search though.

Working with the hoosiers myself there IS a difference between the 25A and 25B (harder and softer compounds respectively) when looking at the data but overall performance is identical. Its been a while but if i remember correctly the characteristics were similar but one gave a higher Mu coef. as to be expected. As claude mentioned though its all about fitting your needs to a tire!

[hsulaimon]

Interesting comments. The reason I asked was because we're a team in our first year of any type of Formula competition and for a while we had been set on Hoosier tires for no good reason other than that everyone else was using them. It's our first year in any kind of Formula competition so due to limited resources we are unfortunately not a part of TTC right now but it's something I agree that we (well my successors) should invest in. But for now, Avon gives us data on self aligning torque and lateral corner force from they're testing rig for a decent range of camber, loading, and slip angles as well as Pacejka coefficients. So by choosing them, we know a good bit more about what kind of setup we need to make the tire work than we would if we used Hoosier tires. We would just have the Hoosiers but not know how they work without extensive testing. We're not quite ready to demand customized tires from anywhere but I will certainly think about what you guys said about discovering what you would want in a tire.


I just need some feeling to make sure the Avon tires are not total rubbish but we'll find out after we sift through the data. If there is something really funny like not being able to achieve 0.5G lateral acceleration under any conditions then we'll stay away. But I'm keen on learning about wear characteristics/ first hand experience.

[Zac C]

I don't know anything about the current Avon's or the new compound. The Avon hillclimb tires that a few teams were running 5-6 years ago had good initial grip for stuff like autocross but would start to grain a few laps into endurance. lap times will suffer greatly as a result. I seem to remember the 13's I inspected being kind of heavy too.

but few teams do any sort of regular tire benchmarking. I suggest buying a set and trying them out if funds allow.

[JT A.]

Interesting comments. The reason I asked was because we're a team in our first year of any type of Formula competition and for a while we had been set on Hoosier tires for no good reason other than that everyone else was using them. It's our first year in any kind of Formula competition so due to limited resources we are unfortunately not a part of TTC right now but it's something I agree that we (well my successors should invest in). But for now, Avon gives us data on self aligning torque and lateral corner force from they're testing rig for a decent range of camber, loading, and slip angles as well as Pajecka coefficients. So by choosing them we know a good bit more about what kind of setup we need to make the tire work than we would if we used with Hoosier tires. We would just have the Hoosiers but not know how the work without extensive testing. We're not quite ready to demand customized tires from anywhere but I will certainly think about what you guys said about discovering what you would want in a tire.

I just need some feeling to make sure the Avon tires are not total rubbish but we'll find out after we sift through the data. If there is something really funny like not being able to achieve 0.5G lateral acceleration under any conditions then we'll stay away. But I'm keen on learning about wear characteristics/ first hand experience.

If you have some tire data already fitted into a Pacejka model, some quick hand calculations will tell you roughly how many lateral G's the tires will achieve. As long as you choose the right scaling coefficient to scale the Mu(y) from the test rig to an actual track surface, and reasonable estimates for vehicle weight etc, your calculation should get you within +/- 10%. I'm not sure what type of surface the Avon test machine runs on, but for the Calspan data a scaling factor of 0.6-0.7 gets us in the ballpark.

[jlangholzj]

but for the Calspan data a scaling factor of 0.6-0.7 gets us in the ballpark.

this matches up quite well with what I've seen on our setups as well. Good to know I'm in the ballpark anyway :)

Self aligning torque and lateral force plots themselves will help get you into a great position for design for a multitude of things. Sounds like you guys are on the right track (ba-dum-tss)! If you already have the data and are happy with the performance I'd run the tires and expand on your knowledge of the design/importance of that data first and then a couple years down the road I'd most definitely look into buying into the TTC. It's a pretty low fee for the resources that you'll gain.

We're a member currently and looked at switching from 13" hoosiers to their 10" with the LC0 compound. We decided against it this year however since nobody before us really had a good understanding of the tire data and its importance into design. We had it but never really properly used it. If the team wants to change in the future however, they'll have a much better grasp on its effects and how it will affect the design/performance by changing the tire after this year.

One thing that I've heard from Claude that's stuck with me is "Make it simple and functional before trying to make it complicated" or something along those lines. Looks like you've got a good start.

[BillCobb]

One simple explanation for the .6 to .7 scale factor you say is needed for Calspan data is that you have greatly under-represented the true vehicle dynamics of your car. I.E. your car has a heck of a lot more mechanical understeer than you have factored into your prediction models of it.

If you take realistic geometric and elastic compliance contributions to front and rear axle slip angle modifiers, the Calspan data needs only a little 'correction' (based on some modeling I've posted on the TTC site). Ignorance levels of steering, chassis and driveline under/oversteer contributions is a better scaling factor for the success of the team than which tire to use.

I'd speculate that all the hype about tire max Mu values is non-sense, as the goal of this completion is best delivered by having a smooth driving car. To watch a Star Trek Class car STB because of an inexperienced driver stalling the motor or a tuned up operator spinning the car in a slalom is the height of an unfulfilled design effort.

A team should be able to deliver a winning car regardless of which tire is picked. All the tires 'got there' from good engineering by tire manufacturers. It's not like they have Oscar Meyer printed on the sidewalls. It's just a different solution set with the same goals. Highest Mu is probably down on the list. The sharpest knife usually cuts the operator, sometimes even when they are testing it.

[Zac C]

One simple explanation for the .6 to .7 scale factor you say is needed for Calspan data is that you have greatly under-represented the true vehicle dynamics of your car. I.E. your car has a heck of a lot more mechanical understeer than you have factored into your prediction models of it.

If you take realistic geometric and elastic compliance contributions to front and rear axle slip angle modifiers, the Calspan data needs only a little 'correction' (based on some modeling I've posted on the TTC site). Ignorance levels of steering, chassis and driveline under/oversteer contributions is a better scaling factor for the success of the team than which tire to use.

I'd speculate that all the hype about tire max Mu values is non-sense, as the goal of this completion is best delivered by having a smooth driving car. To watch a Star Trek Class car STB because of an inexperienced driver stalling the motor or a tuned up operator spinning the car in a slalom is the height of an unfulfilled design effort.

A team should be able to deliver a winning car regardless of which tire is picked. All the tires 'got there' from good engineering by tire manufacturers. It's not like they have Oscar Meyer printed on the sidewalls. It's just a different solution set with the same goals. Highest Mu is probably down on the list. The sharpest knife usually cuts the operator, sometimes even when they are testing it.

I would agree with this assessment. My experience has been that at any given competition, 75+% of the field will show up with a car closer to the 'complete basket case' end of the spectrum than something that is well sorted and smooth to drive. It could be something as simple as just not getting the car done early enough to get much testing before comp. I've also seen many cars with poor throttle response, terminal rear toe compliance, and/or alignments so jacked up you wonder how the car is driveable at all. Large design decisions like tire or engine choice generally aren't what prevents the team from being competitive.

As someone that's worked on a couple FSAE tire development projects, I can also confirm that max lateral mu wasn't really a design criteria, especially not from a flat-track test. Our tires didn't even see a flat-track until after production approval. We were more concerned with lap times, durability, subjective feedback from a trained test driver, instrumented vehicle data, and footprint shape/pressure distribution. Ease of manufacture and cost also entered the equation.

[jlangholzj]

As someone that's worked on a couple FSAE tire development projects, I can also confirm that max lateral mu wasn't really a design criteria, especially not from a flat-track test. Our tires didn't even see a flat-track until after production approval. We were more concerned with lap times, durability, subjective feedback from a trained test driver, instrumented vehicle data, and footprint shape/pressure distribution. Ease of manufacture and cost also entered the equation.

Boom. Well put sir :)

[TurboTom]

I would agree with this assessment. My experience has been that at any given competition, 75+% of the field will show up with a car closer to the 'complete basket case' end of the spectrum than something that is well sorted and smooth to drive. It could be something as simple as just not getting the car done early enough to get much testing before comp. I've also seen many cars with poor throttle response, terminal rear toe compliance, and/or alignments so jacked up you wonder how the car is driveable at all. Large design decisions like tire or engine choice generally aren't what prevents the team from being competitive.

I Agree with Zac C 100% here. Especially as a first year team, your goal is to just finish all events. Sounds like you have some sound engineering behind the decision to use this tyre, so close this tyre 'book' and move on. Maybe some consideration should be taken in your tyre choice for future years in terms of infrastructure (e.g. if the goal is to eventually go 10", its easier to just go there than to change from 13" later on).

In terms of teams that have had experience with Avon tyres, I know that Monash Motorsport have used them previously (before moving to Goodyears, then 10" Hoosiers) and they still know a fair bit about them, they turned up this year with Avon 13" wets should it rain! Oxford brookes Racing have been plugging the Avon's for forever as well, so it would be worth reaching out to those guys. I know Monash are a reasonably friendly lot, don't know about OBR as I haven't dealt with them.

From my experience with the LC0, and with a reasonably competitive car (when moving), 1.5-1.6g for a non aero car will be competitive.You could make a simple weight transfer spreadsheet, with a basic tyre load sensitivity model and assume all tyres operate at peak slip angles to check peak grip if you are concerned about peak Mu.

[Z]

I'd speculate that all the hype about tire max Mu values is non-sense, as the goal of this competition is best delivered by having a smooth driving car.
...
A team should be able to deliver a winning car regardless of which tire is picked.


Originally posted by Zac C:
I would agree with this assessment. My experience has been that at any given competition, 75+% of the field will show up with a car closer to the 'complete basket case' end of the spectrum than something that is well sorted and smooth to drive. It could be something as simple as just not getting the car done early enough to get much testing before comp. I've also seen many cars with poor throttle response, terminal rear toe compliance, and/or alignments so jacked up you wonder how the car is driveable at all. Large design decisions like tire or engine choice generally aren't what prevents the team from being competitive.

Missed this thread earlier, but I agree 100% with Bill and Zac's views above.
~o0o~

Hsulaimon,

It seems that you have not done any homework on this subject. If you had, then you would know that as a first year team your goal is to BUILD A CAR THAT CAN DRIVE 30 KMS, AT AN AVERAGE SPEED OF 50 KPH. Simple as that! Do this (which is possible even on wheelbarrow tyres!), and you will beat at least half the other teams, and be considered a successful Newbie Team.

But instead, my guess is that you are already half way through your year (what comp are you going to?), and you are still theorising about "optimum tyre choice". I predict many DNS'd events... :(

So here is a little test to see what you have learnt about tyres so far.

Q1. What changes would you have to make to the above hypothetical, but potentially quite successful, wheelbarrow-tyre equipped car, so that you have the "... kind of setup we need to make the [Avon/Hoosier/Brand-X racing] tire work"?

Please take this seriously and list all potential "setup" changes, or even whole car design changes, that would be needed.

Q2. (For bonus points.) In what possible universe would an Avon racing tyre "not be... able to achieve 0.5G lateral acceleration under any conditions..."???

Z