Tyre Compounds; Hoosier R25B vs. Goodyear R075

[Chris Lane]

Just wanted to hear some discussion regarding the comparison of the Goodyear R075 and Hoosier R25B tyre compounds...

I'm tossing up which to use. I have read that the Hoosier is cheaper and more forgiving, but the Goodyear is reputably faster but easier to damage through wrong settings and poor heat-cycle management. We only have so much money to spend on tyres after all...

We're a first year team so we have no data or driver feedback to go on, so the choice is being made on what other people are telling us about each tyre.

For reference, tossing up between the Goodyear D2692 20.0x7.0-13 R075's, the Hoosier 43162 20.5x7.0-13 R25B's, or for a thinner option the Hoosier 43128 20.5 x 6.0-13 R25B's.

Oh, and what's the difference between the R25A and R25B compounds?

Thoughts? Comments?

[exFSAE]

The best thing to do is to test two back to back and make a decision based on that. I understand money is always tight.. but there's always money out there.

That said, keep in mind that what works well for one car/driver/team, may not work well for you. One team may be a few tenths quicker on a Goodyear than Hoosier, while another team may be quicker on a Hoosier than Goodyear. Need to find whatever is best for you.

The old Goodyear compound, R065 on the D1385 and D2509, was easy to damage and grain all to hell with a little too much sliding, or scrub, or camber, or heat. I recall that's why my team got off of them in 2004. The R075 from what I've seen holds up much better, particularly in heat.

I've been told the Goodyear D2692 is a bit more forgiving than the latest and greatest Hoosier offering, but that's pretty subjective.

Keep in mind there are other options as well.. Hoosier has a 20.0x7.5-13 R25B, and Goodyear has the D2691 in R065.

A good option would probably be to contact both tire companies directly. Formula_SAE@goodyear.com is GY's contact address and I think Jeff (jaspeer@hoosiertire.com) is still Hoosier's. Tell them you're a first year team, maybe ask suggestions on different constructions, different compounds, get information straight from the horse's mouth as to what temp they come in at.. etc.

[The AFX Master]

Originally posted by Chris Lane:

We're a first year team so we have no data or driver feedback to go on, so the choice is being made on what other people are telling us about each tyre.


the best way to know the differences between tyres, is to join the TTC right now http://fsae.com/groupee_common/emoticons/icon_biggrin.gif.. TTC will provide you with real test data on each tyre to do your suspension design based on a tyre of your choice..

http://fsae.com/eve/forums/a/tpc/f/125607348/m/15510029041

[exFSAE]

True.. though TTC data will not tell you how fast a compound will come in.. and isn't necessarily indicative of peak grip.

[The AFX Master]

agreed, TTC doesn't take into account things as heat cycles and such. but i'll help you to design a suspension that can handle properly the characteristics of each tire

[Chris Lane]

Originally posted by The AFX Master:

the best way to know the differences between tyres, is to join the TTC right now http://fsae.com/groupee_common/emoticons/icon_biggrin.gif.. TTC will provide you with real test data on each tyre to do your suspension design based on a tyre of your choice..

http://fsae.com/eve/forums/a/tpc/f/125607348/m/15510029041

The suspension design is already done, and I did it with the Goodyears in mind. I must be somewhere near the mark as one of our lecturers has used the tyre before when he did FSAE. I have quite a bit of adjustability built in in case it doesn't turn out the way we intended.

It is hard for me to justify spending $500 on TTC data this late in the game for us. That is our steering rack money right there, and we're running tight as it is.

ExFSAE: I have not emailed Hoosier yet, but Goodyear told me to bugger off with the 'we do not give out information on this tyre' line. I was simply asking for dimensional data!

Not keen on tyres wider than 7.0". My feeling is we'll just manage to heat up the 7's at race-pace. I also want to be on one of the latest compounds so next years' guys have more to work with.

[PSUAlum06]

+1 for joining the TTC. It will give you good data to base your suspension design on.

I can't speak to much about Hoosiers offerings, but hopefully I can shed some light on the Goodyear tire codes.

The D2692 is actually a pretty forgiving tire. Outside of running massive amounts of camber (think Nascar) there isn't a whole lot you can do to this that it'll grain or fall apart on you. It's also a pretty easy tire to drive.

The D2691 is the "wet" tire, but some teams use it in the dry. You have to be pretty careful with that though. It's supposedly an old F1 qualifying compound and it comes up to temp pretty fast, but in hot conditions(FSAE West) it can turn into a bit of a handful towards the end of endurance. It also grains easily if you don't get some heat cycles on it before comp.

They also have both a hand carved D2691 "intermediate" and a molded rain tire. In my opinion, the molded rain is to be avoided outside of monsoon conditions. The hand-carved 2691 does a really good job of getting water out from underneath the footprint.

But the single biggest piece of tire advice I can give you is to scuff your tires in before competition.

[exFSAE]

Kind of surprising Goodyear blew you off like that. Poor form. Could try askin again.

If its for this year yea, don't bother with TTC till after your comp and you're into next design cycle. When you do get to that point, it is a REALLY good $500 to invest. I don't know when the Aus comp is.. but if its gettin tight, just get *a* tire and work with it. Better to have a driving car than some data and a car missing a steering rack, eh? http://fsae.com/groupee_common/emoticons/icon_smile.gif

It will be more important anyway to just have something ready when the car is good to go and getting the drive time. Other thing to take a look at.. results from the previous US and Aus competitions. Top 5-15 in the driving events should give you a good idea what's dominant.

Regarding scrubbing tires in.. yea. Good call. Haney and whoever say that sticker tires are the fastest you're gonna have em.. but I don't buy it. There's some time for the tire to come in. They need a good scrub. Otherwise your outlap (aka.. ONE lap for auto-x) is gonna be like ice skating. We had that happen a few years ago.

PSU.. Penn State? I thought you guys were on Avons for the longest time?

[PSUAlum06]

I'm also a little surprised Goodyear blew you off. what "dimensional" data were you asking for? If you're looking for stuff like spring rates, cornering power values, etc. you probably won't get those from any tire manufacturer. And even then you won't be able to make an A to B comparison between two manufacturers because of different test conditions, test machines, etc.

I don't buy that about sticker tires either. You at least want to be sure that you aren't running on mold release or vents.

[ZRubenson]

Originally posted by Chris Lane:
Oh, and what's the difference between the R25A and R25B compounds?


When I called and asked about that, the guys at Hoosier said that they're chemically the same compound, but the r25B's are made by a different manufacturer. So in theory, they're the same tire. On the other hand, I've had quite a few people who've driven on both tell me that the two tires feel different, and that the r25A heats up a bit quicker.

[Chris Lane]

Originally posted by PSUAlum06:
I'm also a little surprised Goodyear blew you off. what "dimensional" data were you asking for? If you're looking for stuff like spring rates, cornering power values, etc. you probably won't get those from any tire manufacturer. And even then you won't be able to make an A to B comparison between two manufacturers because of different test conditions, test machines, etc.

I don't buy that about sticker tires either. You at least want to be sure that you aren't running on mold release or vents.

Nah just pure dimensions; bead width, section width, etc.

[PSUAlum06]

Section widths and recommended rim widths are given on the Goodyear Racing website.

http://www.racegoodyear.com/pdf/2008_pricebook/eagle_sport.pdf

[Chris Lane]

Yeah, thanks but I already found that pdf. The only problem with that data is they don't list the rim width the measurements were taken on. A fairly minor point...

[MrSwa]

I went and asked the Hoosier guy at comp this year about A vs B. He said that they are the same basic tire and that the formula is just a little different. The B, the new one, is supposed to have better tread wear and life than the old As. We only have experience with the As so I can't give you any "hands on" exp.
We are currently going through this same debate. We currently run R25As but are probably going to get a set of Goodyears to test on this summer.

EDIT: The guy also told us that they no longer are making the R25A compound. Just remembered and thought I'd share.

[lporter]

On last year's car we used R25A's in the front and R25B's in the rear. The first thing we noticed was the increased tread life of the B compound, at least 2 times better in most situations.

I had a long discussion with Jeff Speer from Hoosier before I ordered the tires for this year. According to him the B compound was specifically developed to compete with Avon in Formula Continental with the goals of better tread life, faster temperature accumulation and a broad grip envelope (i.e. the limit is not a razor's edge).

From testing this year I will agree on all 3 points, our car ran nearly 4 weekends of testing on a single set of tires (granted this was in the middle of April in upstate New York with an average track temp of 50 degrees). The only difference is that the sidewall is slightly stiffer than the A compound and there is no TTC data yet, but we've found that both types respond well to similar suspension set-ups.

From a first year-team/ budget point of view I would recommend the R25B purely for its wear properties, although I have no experience with any other tire so I could be completely wrong. I think someone from UWA (Pete Marsh?) made a post on a comparison of Goodyears vs. Hoosiers, might be worth a look. Hope this helps.