Using 1 set of tires (Goodyear intermediates)

[carreshwell]

Hey Guys
We are a new team. Our team can't afford two set of tires and rims. So, we are planning to use just Goodyear intermediate tires on dry as well as wet surface. I have a few questions:
How seriously could it hinder our performance on dry surface?
Do the treads wear off quickly?
Could you guys suggest us a better alternative option?
Thanks

[M. Nader]

effect of speed, Probably a lot!

what kind of budget are you on? or is it that the team has better things to pay for than tires?

[Zac]

While it is certainly possible to win using the Goodyear intermediate in the dry (UWA did that at Michigan in 08) I wouldn't recommend it. Rain compounds are great for short stints (autocross, skid pad) since they come up to temperature quickly, but they will overheat and fall off quickly towards the end of endurance. For a team with a limited budget you would not get any practice time on a single set of tires.

There are a couple things that I would do in your position. First, would be to pick up a set of actual dry tires to use for competition and your final testing. I would also look for a set of steel wheels with standard passenger car tires (possibly look into hot lapping them as well) to use as your wets and/or initial shakedown tires. The last thing I would do is see if any local-ish open wheel teams have take-offs you can snag for free or only a couple bucks. They wouldn't be great for competition, but would be enough for driver training and roughing out a setup.

[Pete Marsh]

The compounding is the same on both the inter and dry Goodyear tyres as far as I am aware. However the grooves significantly increase the heat in the tyre, and hurt the feel/accuracy.

The answer to your question depends a lot on track temp, vehicle weight, and driver skill but I would say that is a good way to go to maximise your performance from one set of tyres.

You will get a gain in the short events, but must have the driver skill and discipline (and vehicle balance) not to excessively slide the car in enduro.

As for testing though, I'm not so sure you will get your testing AND comp from one set. Maybe, if your car is light. Perhaps anything round and black for initial reliability testing and engine tuning etc. We use second hand Formula Ford front tyres, which are often free.

I just drove on them in the rain yesterday for a display. The grip in the wet is truly amazing.

[carreshwell]

Nader, we are not exactly sure about how much money we will be able to get, but its a certainty that we will be short on money. I think we should try to save money on other parts and try to give priority to tires.
Thank you all for your views.

[JulianH]

IF you only have one tire, the Goodyear Inter is clearly the right choice. We drove incredible SkidPad times with old Goodyear Inters in the dry.

But they melt like ice cream in the sun, we did half an Endurance in the dry and they were nearly gone.

It is always possible to get old tires from teams (e.g. we switched from 13 inch to 10 inch this year and have some old Hoosier slicks which don't have a lot of use anymore...) at a reasonable price. Ask "older" teams nearby, they should have some rubber for your.


Cheers

[M. Nader]

Originally posted by carreshwell:
Nader, we are not exactly sure about how much money we will be able to get, but its a certainty that we will be short on money. I think we should try to save money on other parts and try to give priority to tires.
Thank you all for your views.

After reading the replies you are getting for dry running i would recommend getting a set of drys, as others said it is nearly impossible to do endurance on just a set of inters. and i believe wet sets (like in Hoosier would make you really slow, but not sure about their wear rate though.

i would say get a set of drys with their rims, and look local for any street legal tires and local cheap rims that can be fitted to your hub designs (even if you need to add a flange for it to work). tires that you fit to your car can handle FSAE wet and not be off the pace.

at FS UK changing tires on the same rim was 20 UK pounds per set which i think is a lot specially since the weather was constantly changing. so getting 2 sets of tires and rims is the minimum i can recommend, testing is a whole other story though.

[SNasello]

The goodyear wets are definitely NOT the same compound as the drys, and i would not recommend running them very long in the dry. I would rather recommend a set of goodyear drys, and hope that it doesn't rain. You can get a decent 400km out of a set of goodyear drys, with them still performing almost as they were new.

I would also just recommend a set of street tires for rain.

Also, i believe Continental supports Formula Student teams, I don't know to what extent though. You could try contacting them. The conti rains are actually pretty good.

[Zac]

Originally posted by M. Nader:

tires that you fit to your car can handle FSAE wet and not be off the pace.



This isn't true at all. A wet race compound will have twice the grip of a passenger car tire, particularly one that is designed for a car that still takes 13" wheels. What a passenger tire will let you do though is compete.

[M. Nader]

Originally posted by Zac:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by M. Nader:

tires that you fit to your car can handle FSAE wet and not be off the pace.



This isn't true at all. A wet race compound will have twice the grip of a passenger car tire, particularly one that is designed for a car that still takes 13" wheels. What a passenger tire will let you do though is compete. </div></BLOCKQUOTE>

I know that but i just recommended what i would do if i was in his place.

are you sure about the "twice the grip"? i am genuinely interested on how slower is it

[Michael Royce]

carrswell,
I agree with M. Nader. As a new team, your first objective should be to complete all events. So being a bit slower if it is wet in the Endurance or Autocross will not prevent you achieving your primary objective. But you will need rain tyres of some type. If you run intermediates, it is quite possible that you will wear them sufficiently that they will be below minimum tread depth and the scrutineers will not pass them as being suitable in the wet.

If you are very short of cash, buy a set of dries on reasonable rims, and use a set of passenger car tyres on steel wheels as your "rains".

[Zac]

Originally posted by M. Nader:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Zac:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by M. Nader:

tires that you fit to your car can handle FSAE wet and not be off the pace.



This isn't true at all. A wet race compound will have twice the grip of a passenger car tire, particularly one that is designed for a car that still takes 13" wheels. What a passenger tire will let you do though is compete. </div></BLOCKQUOTE>

I know that but i just recommended what i would do if i was in his place.

are you sure about the "twice the grip"? i am genuinely interested on how slower is it </div></BLOCKQUOTE>

Go out and test it yourself, or look through historical data. Teams have still pulled close to 1 g on a wet skid pad with cold intermediates. A "broadmarket" passenger tire will feature a tread compound designed for rolling resistance and treadwear, two performances that go directly against wet grip. It'll also feature a construction that's far from ideal for FSAE loading. I would expect ~.5g lateral maximum from that kind of application.

It will get you around the course though which is what really matters for a first year team.

[M. Nader]

Originally posted by Zac:

Go out and test it yourself, or look through historical data. Teams have still pulled close to 1 g on a wet skid pad with cold intermediates. A "broadmarket" passenger tire will feature a tread compound designed for rolling resistance and treadwear, two performances that go directly against wet grip. It'll also feature a construction that's far from ideal for FSAE loading. I would expect ~.5g lateral maximum from that kind of application.

It will get you around the course though which is what really matters for a first year team.

I guess you are right, the highest G force i can remember for a dry passenger car using low end road tires (13" normal car , say a civic for example) would be less than 0.9G on skidpad. now add rain to that and i think your 0.5G adds up.

@Carreshwell at FSUK this year only 27 cars out of the 103 entrants finished endurance. Food for thought

[Tom Wettenhall]

IIT Roorkee came to the Australian comp last year with one set of passenger car tyres.

For a new team, I'd say put your money into investment purchases which you can use for a number of years. Get a good ECU now so you don't have to waste your money on an upgrade next year. Get good dampers. Get a spare engine. As important as good tyres are for an established team, they're disposable which means they won't be there next year when you have the experience to start putting enough pace in to your car to use them.

Go to comp with whatever you can find that's round and black, as Pete said, (+1 for secondhand FFords - the most fun tyres you can put on an SAE car and dirt cheap) and next year when you've got top quality, reliable parts where it matters, you can spend the money you might otherwise have spent on upgrades on good tyres. If you finish every event in your first year I can just about guarantee you'll beat all the teams who think it's better to spend money on good tyres than a reliable car. There's a few of them.

(Preemptively, in case I've seemingly implied that teams not finishing enduro have their priorities wrong: That's not what I meant. Teams spending more on performance than just making their car go have their priorities wrong.)

[Edward M. Kasprzak]

Originally posted by Zac:
While it is certainly possible to win using the Goodyear intermediate in the dry (UWA did that at Michigan in 08) I wouldn't recommend it. Rain compounds are great for short stints (autocross, skid pad) since they come up to temperature quickly, but they will overheat and fall off quickly towards the end of endurance. For a team with a limited budget you would not get any practice time on a single set of tires.

There are a couple things that I would do in your position. First, would be to pick up a set of actual dry tires to use for competition and your final testing. I would also look for a set of steel wheels with standard passenger car tires (possibly look into hot lapping them as well) to use as your wets and/or initial shakedown tires. The last thing I would do is see if any local-ish open wheel teams have take-offs you can snag for free or only a couple bucks. They wouldn't be great for competition, but would be enough for driver training and roughing out a setup.

I agree with Zac. I think it's essential to have a proper set of dry tires for competition. Keep in mind that everything on your car exists for one of two reasons: either to get the most performance out of your tires or for driver safety. The easiest way to get more out of your tires is to use better tires.

A set of passenger car tires for driver training, shaking the car down and possibly even for wet running at competition is a possible place to save some money. If you only have one set of inters you can't do any meaningful testing.

As said by several posters above, look for secondhand tires. Many teams simply throw away (recycle) their old tires, when they could be selling them to you for a nominal cost, or even give them to you for free. They probably won't have a "for sale" sign--it doesn't hurt to ask.

Given the importance of the tires, as a design judge I will ask a lot of questions when a team uses passenger car tires or inters as their dry tire. Tires are one of the absolute last places you want to make massive compromises because of the budget. If you spend money anywhere else on the car and show up with a questionable tire choice it will always raise a big red flag. Prioritizing your budget is an important part of any engineering project.

And at the risk of sounding harsh: If you have already spent the bare minimum everywhere on the car and still can't afford a proper set of tires then you have an insufficient budget for this project/competition. Abort.

[NickFavazzo]

I don't think you need the best tyres, what you need is a tyre (and vehicle components) that meet your teams performance goals and budget. Some goals are simply to finish dynamic events, some goals are to win all dynamic events, each can be done with very different vehicles. Honestly FFords are a great starting point and will allow you to focus on developing how to make a car fast by tuning the vehicle and driver as well as developing your Vehicle Dynamics knowledge. After all, there are plenty of points to be gained in events that don't even make use of the tyres..

[Tom Wettenhall]

Seems there's two schools of thought here. I may be wrong, but it looks to me like:

The people saying that the best tyres are absolutely essential are thinking in terms of maximising points for this year's competition like any established team would do. Learn by doing.

The people recommending Formula Fords, inters or passenger car tyres are thinking in terms of putting a first year team in the best position to finish all events at their first comp and set them up as well as possible for future years.

As Nick said, performance goals...


Offhand, can you make a case in design that a weekend autocross racer would benefit from having cheap and easy to source tyres such as Formula Fords? Or is the dynamic tradeoff considered too bad?

[Edward M. Kasprzak]

Offhand, can you make a case in design that a weekend autocross racer would benefit from having cheap and easy to source tyres such as Formula Fords? Or is the dynamic tradeoff considered too bad?

Such a case could be made, but I would say the same thing about just about anything on the car! There are few things which can be "pre-judged" in the design event. The design event evaluates your knowledge and your process. As design judges we ask a lot of "why" questions. We want to know that you can defend your design choices. The vast majority of design judges I have worked with have an open-minded approach--there aren't too many "right" and "wrong" decisions. Instead, there are ones which you either can or cannot defend. As mentioned in other posts, team goals play into the ability to defend a decision, as does your engineering analysis, your organizational skills and your presentation skills.

Just because something raises a red flag doesn't mean it's "bad" or that it isn't going to score points. Instead it's a place where I'm going to ask more questions. Its great when I ask about something questionable and the team opens their notebook/spreadsheet and shows me a few graphs or tables which support their decision. I then ask more questions to assess the validity of the calculations and the process. If a decision can be defended based on appropriate team goals and solid engineering analysis then it scores well. You need to show that you arrived at your solution via a proper engineering design process.