Tyres for 10 inch rims

[Big Bird]

Hi all,

Just wondering if we could get some dialogue going on which tyres work and which don't on ten inch rims. We ran Dunlop tyres on our little single last year, they took ages to warm up and therefore weren't too flash for the autocross and skid pad events.

I don't know what the compund designation was for them, but they were the only Dunlop 10's available here in Oz. They were manufactured for a comp in Japan for little open wheelers with Hayabusa engines in them. Therefore quite a hard compound. The good thing is I reckon there is a good ten to fifteen years worth of testing in each set before they wear out.http://fsae.com/groupee_common/emoticons/icon_smile.gif

Any comments from those teams that have used Hoosiers and Goodyears? Anyone tried LeConts?? Anyone want to tell us we are Wallys for using tens in the first place? (Please form an orderly queue, yes Pat D'Rat you can be first in line).

I know there have been previous threads on 10's versus 13's, but most focus on geometry and weight. Would love to hear some good info on the actual handling and heating characteristics.

Cheers all,

Geoff Pearson
RMIT FSAE 2003

Design it. Build it. Write it off two weeks before the event.

[Big Bird]

Hi all,

Just wondering if we could get some dialogue going on which tyres work and which don't on ten inch rims. We ran Dunlop tyres on our little single last year, they took ages to warm up and therefore weren't too flash for the autocross and skid pad events.

I don't know what the compund designation was for them, but they were the only Dunlop 10's available here in Oz. They were manufactured for a comp in Japan for little open wheelers with Hayabusa engines in them. Therefore quite a hard compound. The good thing is I reckon there is a good ten to fifteen years worth of testing in each set before they wear out.http://fsae.com/groupee_common/emoticons/icon_smile.gif

Any comments from those teams that have used Hoosiers and Goodyears? Anyone tried LeConts?? Anyone want to tell us we are Wallys for using tens in the first place? (Please form an orderly queue, yes Pat D'Rat you can be first in line).

I know there have been previous threads on 10's versus 13's, but most focus on geometry and weight. Would love to hear some good info on the actual handling and heating characteristics.

Cheers all,

Geoff Pearson
RMIT FSAE 2003

Design it. Build it. Write it off two weeks before the event.

[PatClarke]

http://fsae.com/groupee_common/emoticons/icon_biggrin.gif
PDR

I'd give my right arm to be ambidextrous!

[PatClarke]

Deafening response, isn't it?
PDR

I'd give my right arm to be ambidextrous!

[Aaron Harnden]

Geoff,
Your not alone. We also seek the answers to your questions. If we come up with anything meaningful, I'll be happy to forward it on. Good luck to you and your team in the Formula Student comp.

Cheers,

Phantom Engineering
Chief Design Engineer 2004

I may not always be right, but i'm never wrong...

[Eric Wort]

Tire deflection with the 10 inch wheels was a little bit much for my taste: http://www.ec.uiuc.edu/soc/sae/formula/img/detroit02/008.jpg

I suppose you could make them work with lots of static negative camber and/or lots of camber gain in bump, but that doesn't seem too ideal to me. I did see some low-profile Goodyears and Hoosiers on 10s at competition last year, those might be decent, but I've never driven on them.

We spent a half-summer setting up the suspension on our 2002 for the 10s. We switched to 13s and immediately dropped 1.4 seconds on a 40 second lap, then dropped another second off after re-tuning the suspension for the 13s.

Back in 2000, Goodyear sent us some prototype tires for 10s which had a really stiff sidewall. Too bad they never decided to make them, they were wonderful tires to drive on, almost as good as 13s http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

Eric Wort
UIUC Formula SAE (http://dilbert.cen.uiuc.edu/soc/sae/formula/)

[Foote]

We at western have never made a car with 13" wheels, they have all been 10. keep in mind that you essentially have four flywheels on your car. You have to accelerate and decelerate them with power from the engine and brakes. Lowering the polar moment of inertia of the wheels should result in faster acceleration and better braking.
as for sidewall flex, i've never been entirely convinced that it should be feared so much. remember that the only way a car can corner is through the flexing of its rubber. cars with too small of sidewalls or too stiff of sidewalls lose their tires much more often. that's why no racing class uses low profile tires. (unless you count scca)

just my thoughts

Justin Foote
WWU FSAE

[Charlie]

Try sports car racing for some low-profile tires. Everything else is regulated. Firestone wanted to go to 17" tires for CART in 1994-5 (whenever they re-entered the series) but CART wouldn't let them, supposedly on the basis of appearance.

-Charlie Ping

I just need enough to tide me over until I need more.

[jack]

...yeah well here at western, along with our ten's we also run kpi and scrub that would give other teams nightmares...

jack @ WWU
http://www.etec.wwu.edu/

[Sam Jowa]

Jack, Enlighten us with some numbers.

SJ

[PatClarke]

Quote Jack....."we also run kpi and scrub that would give other teams nightmares..."

The reason teams with 10" wheels run 'Way out there' kpi and scrub numbers is because of the lack of real estate within the wheel for a proper upright design. If the angles are about right, the toebase, steering arm and kingpin lengths are insufficient. The judges know this and will quiz you about it. You really have to have a full understanding of your geometry ...probably more than a team with 13" wheels http://fsae.com/groupee_common/emoticons/icon_wink.gif.

And, as Enormous Avian has found, the choice of suitable tyres is as rare as (Big) birds teeth http://fsae.com/groupee_common/emoticons/icon_razz.gif.

One last word of advice. Never choose a tyre designed for a 'One Make' race series. They are always hard compound tyres optimised for a longer competitive life rather than ultimate grip from cold. If you cannot find a company who make tyres especially for FSAE, then try find a company who make tyres for small lightweight hillclimb or sprint cars, or a company who will make tyres especially to your requirements.
NOTHING will frustrate an otherwise competitive team more than having uncompetitive tyres. Heed the words of Mr.Wort (Are you related to Rag Wort?) ..quote......"We switched to 13s and immediately dropped 1.4 seconds on a 40 second lap, then dropped another second off after re-tuning the suspension for the 13s."
There is much wisdom in there! Especially if the car is designed forr 13" wheels.
Oh, following that logic, why not 15" or 17" or 19" wheels?? Well suitable tyres for that size wheel are unavailable as far as I am aware.
PDR

I'd give my right arm to be ambidextrous!

[jack]

i knew this would desolve into the "10 inch sucks forum". this is hopefully going to be our last car with 10's, but for several reasons; to get back to bigbirds original question, one of the major reasons we plan to go with 13's in the future is because you can get about 4 13's for the price of one 10, also you can get a million different kinds of tires in 13, which will solve your ten inch woes.

sam, think about a reasonably high kpi and scrub, then double it http://fsae.com/groupee_common/emoticons/icon_wink.gif. pat, i sure did learn alot about suspension geometry with this setup though, and honestly i dont think it is as bad as everyone thinks...i think there are some adventages...now all i need to do is convince those judges...

jack @ WWU
http://www.etec.wwu.edu/

[rotor]

one thing that hasnt been mentioned is that the extra sidewall height in a 10in gives the tyre more complience and is less sensitive to wheel alignment. Does this outway the disadvantages of less space?

RMIT Racing

[PatClarke]

Rotor, you have a perfect opportunity to prove your point in Bruntingthorpe in July http://fsae.com/groupee_common/emoticons/icon_wink.gif
And Jack, never once have I said that 10" sucks (Well not lately) http://fsae.com/groupee_common/emoticons/icon_smile.gif and you get one more opportunity to persuade the judges to accept your point of View at Pontiac in May.
See you all in both places and I'm looking forward to it.
PDR

I'd give my right arm to be ambidextrous!

[Big Bird]

Some very interesting responses here, thanks for that everyone. A few comments if I may.

Justin Foote, you have hit on one of the reasons we went the 10 inch route in 2003 - inertia, (as opposed to weight). We chose an engine with low outright power but with low MoI too (a 450 single), and pushed to reduce all other rotating mass in the car to retain reasonable acceleration. We'll get around to measuring comparitive MoI's one day soon, will post results for anyones interest.

Charlie, thanks for the private mail and advice, most appreciated.

Pat, I knew the bulk volume of response would come from you. Your pathological hatred of 10's preceeds you! A few points of reply if I may:
* Certainly agree that packaging is an issue, but I don't think 3 degrees of KPI or 55mm of scrub is particularly "out there", especially with opposed piston calipers. We made some compromises, but we understood them, just as going 13's to reduce these values would have compromised our weight. Our car handled fine and worked well even with the dodgy tyres we did have.
* As for steering arm length, we've only had one comment from a driver that the steering was heavy (UoW "guest" driver), and that was immediately followed by his team mate who told us that our steering was too light. Make the car light enough and requirements for large toebases, steering arms diminish too.
* "Judges know this and will quiz you about it. You really have to have a full understanding of your geometry....". Oh I wish they had. Claude Rouelle, if you are reading this, please please PLEASE come to FSAE-A 2004. I'll pay your airfare if I have to....
*"Enormous Avian"? Doesn't quite roll off the tongue, does it. I'll give it a go, see if it sticks...
*I'd seriously question the implication that 10's will make you uncompetitive. Without wishing to blow wind up our own backsides, Rotor's times in our car surely disproved this. And while I have nothing but praise for his driving skills, I'd challenge anyone who saw him ontrack to convince us that the car was being driven beyond its capabilities. There were a lot of supposedly better designed cars having the wheels (13") driven off them behind us.

Jack, another of the reasons we went for the 10's was that we could actually get the tyres and rims cheaper here in Oz - (EVERYTHING is back-to-front down here http://fsae.com/groupee_common/emoticons/icon_smile.gif ) And in the original context of the competition, being competitive on a budget is what we should all be aiming for.

As a closing remark on the design arguments in the great wheel debate, we all have to make compromises one way or the other. The trick to good design is to carefully choose what compromises you do make, such that the final product works as a whole. In our case, persuing the lightweight single cylinder route, I think there is merit in trading some toe base, scrub radius, etc, for the advantages in weight and inertia. For a team with a larger, more powerful car, this might not be the case. Horses for courses.

Off the soapbox now, and kicking myself I got sucked into geometry arguments. Anyone else got some stories about what specific 10 inch tyres did and didn't work?

Cheers,

Geoff Pearson
RMIT FSAE 2003

Design it. Build it. Write it off two weeks before the event.

[PatClarke]

Geoff, Geoff, Geoff =]
I don't have a pathological hatred of 10" wheels. I LOVED the several Cooper S's I owned once upon a time http://fsae.com/groupee_common/emoticons/icon_smile.gif
PDR

I'd give my right arm to be ambidextrous!

[James Waltman]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by jack:
one of the major reasons we plan to go with 13's in the future is because you can get about 4 13's for the price of one 10 <HR></BLOCKQUOTE>

Actually Jack, you got it backwards. I just ordered another set of 10 inch rims last week. They were US$31.50 each. For the set of four that makes about US$126.00. I know that there are teams out there paying twice that per wheel for the 13s.

We do have to add a stiffener to our wheels but that is easy for us. So we get a very light wheel that hardly costs anything (I think that actual retail price is around US$45.00).

As far as the tires go we have just switched to Goodyear this year after many years of Hoosier. We will be able to start testing them in a few weeks. One thing we've noticed so far is how much stiffer the sidewalls are on the Goodyears.

James Waltman
http://dot.etec.wwu.edu/fsae/
Vehicle Research Institute at
Western Washington University

[Ryan Schoffer]

we have been running 10 iunch rims for awhil enow - here is a bit of my advice

-the hoosier's are too hard, and they dont ofer any slip angle data, so we dont use them
-the goodyears are a beter tire, but dont last very long because of the soft compound, and need to be heat cycled very carefully to begin with, you can get slip angle data etc. for them
-as far as rain tires go, you are stuck with the hoosiers, but they seem to work fine

also, you may want to check into what width you are using, we found from the goodyear tire data that we will get better traction with the same width on all for corners, as opposed to wider back tires, to increase contact pressure

Vehicle electronics leader

www.ucalgary.ca/fsae (http://www.ucalgary.ca/fsae)

[Charlie]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Ryan Schoffer:
-the hoosier's are too hard, and they dont ofer any slip angle data, so we dont use them
-the goodyears are a beter tire, but dont last very long because of the soft compound, and need to be heat cycled very carefully to begin with, <HR></BLOCKQUOTE>

That's a suprising statement, in my experience with the 13" tires the Hoosier R25A compound is sifter than Goodyear's R065. Are these the compounds you were using in your comparison? They are the same compounds listed for the Goodyear and Hoosier 10" tires.

-Charlie Ping

I just need enough to tide me over until I need more.

[Big Bird]

Thanks gents. I've heard from some sources that the Goodyear data is quite inaccurate. Any comments?

Mini Cooper S? Now we're talking, the tintop design inspiration for our SAE car. Small, light, agile, underpowered - and I don't fit into either of them http://fsae.com/groupee_common/emoticons/icon_smile.gif

I could probably draw parallels between British build quality and our thing too....

Cheers,

Geoff

Geoff Pearson
RMIT FSAE 2003

Design it. Build it. Write it off two weeks before the event.

[Big Bird]

Oops, just remembered we are going to FStudent this year. Please scratch the insults aimed at the Brits... http://fsae.com/groupee_common/emoticons/icon_smile.gif

Cheers

Geoff Pearson
RMIT FSAE 2003

Design it. Build it. Write it off two weeks before the event.

[jack]

oops...yeah i meant to say tires are cheap for 13's, not rims. i know our rims are dirt cheap (just dont tell anyone what there for http://fsae.com/groupee_common/emoticons/icon_wink.gif). those 10 inch tires are fairly pricey compaired to 13 inch tires.

jack @ WWU
http://www.etec.wwu.edu/

[Ryan Schoffer]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Charlie:
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Ryan Schoffer:
-the hoosier's are too hard, and they dont ofer any slip angle data, so we dont use them
-the goodyears are a beter tire, but dont last very long because of the soft compound, and need to be heat cycled very carefully to begin with, <HR></BLOCKQUOTE>

the hoosiers i was comparing them to are from a couple yars back, so they may have changed the compound - but from what i saw from the tirest at FSAE last year, the hoosiers still seemed alot hader, just from look at them in the hoosier trailer

That's a suprising statement, in my experience with the 13" tires the Hoosier R25A compound is sifter than Goodyear's R065. Are these the compounds you were using in your comparison? They are the same compounds listed for the Goodyear and Hoosier 10" tires.

-Charlie Ping

I just need enough to tide me over until I need more.
<HR></BLOCKQUOTE>

Vehicle electronics leader

www.ucalgary.ca/fsae (http://www.ucalgary.ca/fsae)

[PSU Racing]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Thanks gents. I've heard from some sources that the Goodyear data is quite inaccurate. Any comments?

Geoff Pearson
RMIT FSAE 2003
<HR></BLOCKQUOTE>
Geoff, The Goodyear data on slip angles is inaccurate for our application. If I remeber correctly, they told me the test surface was like 60 grit sandpaper.

Another plus for 10's is they have a smaller contact patch and will get to operating temp quicker.

Garth Frederick
2004 Project Engineer
PSU Racing

1996-2002 Georgia Tech Motorsports Alumni

[Big Daddy]

One question on 10" rims. I take it most of you run Douglas and I heard the word stiffeners thrown out earlier. My question is dose a FSAE car do more to the wheels than say a Formula 500 car? They run douglas wheels and I haven't seen any with stiffeners, Granted I have only seen one or two. Just asking

"A woman is a lot like a beer, they look good, smell good, and you would run over your own mother to get one." Homer Simpson

[James Waltman]

Good question Big Daddy. Maybe the F500 guys run red labels. We run Douglas Blue Labels. They're very thin and are not made for racing vehicles (says so right on the label). They tend to rip apart if they get loaded with high G forces. So they need to get the centers reinforced. This is where the stiffener comes in. Our stiffeners weight about .46lbs each (0.2kg). Our wheels with stiffener weigh 3.85lbs each (1.74kg). We are pretty sure that there is still weight to be lost but it is a lower priority right now. The key to making the stiffeners work is to make sure they transfer the load (some methods are better than others).

I know that this is a tires thread but wheels are an important part of the choice. Is anyone willing to post some weights for other 10's and some 13's? Will anyone share what they paid for their wheels?

Douglas Wheel Strengths (http://www.douglaswheel.com/strengths.htm)

Here come the pictures:

See, says so right on the label.
http://dot.etec.wwu.edu/fsae/SharedPictures/Wheels/No%20racing.JPG

http://dot.etec.wwu.edu/fsae/SharedPictures/Wheels/Full%20wheel%20cracked%20center.jpg

The other side is worse. The center is split nearly the whole way around but it doesn't show up well in the pictures.
http://dot.etec.wwu.edu/fsae/SharedPictures/Wheels/Detail%20wheel%20cracked%20center.jpg

The Solution
http://dot.etec.wwu.edu/fsae/v35/bonding/images/Wheel%20reinforcer_JPG.jpg

http://dot.etec.wwu.edu/fsae/v35/bonding/images/Wheel%20with%20reinforcer%20bonded%20in_JPG.jpg


This thread had a picture of North Carolina State's stiffener that was not very successful. (http://fsae.com/eve/forums?q=Y&a=tpc&s=763607348&f=125607348&m=5756057383&p=1) But man, I like their car.

James Waltman
http://dot.etec.wwu.edu/fsae/
Vehicle Research Institute at
Western Washington University

[Charlie]

Nice engineering on fixing your breakage problem, but I gotta ask if that is happening to the centers how do you know the wheel is not deflecting at the outer rim? Any thoughts on that?

We saw some problems with our Keizers, one reason we went to much heavier but stiffer wheel halves for 2003, our wheels weighed about 8.25lbs each last year, really that much! But I think predictability at the limits is important.

We are looking into ways to lose that weight again this year, but we're going to make sure the stiffness is there first. The 2003 car for us was a very conservative effort that just strove to not overlook basic vehicle concepts... But still a 500lb car with heavy wheels can still do some damage eh? http://fsae.com/groupee_common/emoticons/icon_wink.gif

-Charlie Ping

I just need enough to tide me over until I need more.

[James Waltman]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Charlie:
Nice engineering on fixing your breakage problem, but I gotta ask if that is happening to the centers how do you know the wheel is not deflecting at the outer rim? Any thoughts on that?
<HR></BLOCKQUOTE>

That is a concern that is addressed with the lip design on the stiffener. The real answer is: Yeah, they might be. We are about to start testing all of that kind of stuff. So maybe we will have a good answer later.

On the 500lb car: Yeah a lot of the 500 pound cars did better than us last year because we didn't finish in time. Maybe we spent too much time trying to shed weight... Oh well, I'm proud of what we have now.

James Waltman
http://dot.etec.wwu.edu/fsae/
Vehicle Research Institute at
Western Washington University

[Charlie]

Hey James-

The 500 lb comment wasn't a shot at you or anyone, in fact I should say we weighed in at 491 lbs. http://fsae.com/groupee_common/emoticons/icon_smile.gif I'm just saying our car was chunky and we can do better!

-Charlie Ping

I just need enough to tide me over until I need more.

[Big Daddy]

F500 does use Red Labels all you have to do is ask Douglas and they will tell you what the majority of F500 teams use. So I guess my question now is why don't you just use Red Labels and ditch the stiffener? It should be lighter and the cost isn't that much more I wanna say a bout 10-15 bucks a wheel.

"A woman is a lot like a beer, they look good, smell good, and you would run over your own mother to get one." Homer Simpson

[Travis Garrison]

Big Daddy,

Becuase we felt that the red labels put alot of material where it wasn't needed. When we picked out the wheels we were mostly concerned with punching through, not stiffness....

besides...maybe I have a flawed veiw of this but I look at the wheels and see a bending problem...you want your section at the base not out at the tip...adding section to the flange is dead weight. It makes no sense to me to buy a wheel that has a huge wall all over. If we were to buy the red labels, I'd probably still try to put a stiffener in them since thats the only way I could justify that much material at the outer edge of the wheel.

Reds with a stiffener might be a better option in the end, but we stoped adding weight when we stoped breaking wheels http://fsae.com/groupee_common/emoticons/icon_smile.gif

Travis Garrison
WWU FSAE

[Big Bird]

The outer flange of the rim is in bending under vertical loads. It is also the part that needs to stay nice and round so we don't get any wheel vibration. It also takes the bulk of the impact when beading the tyre. I've seen quite a few rim failures (and subsequent injuries) when the outer rim has blown under beading. I would rather have an extra mm of thickness on the outer flange than worry about such things. Thats just me being overly cautious.

Cheers

Geoff Pearson
RMIT FSAE 2003

Design it. Build it. Write it off two weeks before the event.

[Big Bird]

By the way, we have measured the weight of our red labels as just under 1.9kg, no centres.

Cheers again

Geoff Pearson
RMIT FSAE 2003

Design it. Build it. Write it off two weeks before the event.

[jack]

big bird,
on all of our old cars here at WWU, we have run blues with stiffeners. we have failed only two of those wheels, one shown above, and one...well...the car fell off the back of the truck...anyway, the old cars get pretty trashed, and they all have the same wheels that they had in detriot years ago. i know that our rims (at least the insides) arent deflecting much because there is only .05-.1" clearance between the brake and rim, and no signs of rubbing.

oh, and if your worried about the bead taking out your eyeballs, just have the guys at the local tire shop do it for ya http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

jack @ WWU
http://www.etec.wwu.edu/

[NJM.]

We have run 10s for a couple of years now with success, 8th place FSAE in 2003, and have found that you can get good performance with them. I have to disagree with PDR in that we were able to achieve very acceptable outboard geometry, near zero scrub with 1.5 degree KPI. It just took a lot of work to package everything deep inside the wheel and a little creativity on a-arms to get the required amount of steering lock. The smaller rotor is no problem, as we were able to brake consistently at the limit. I would say in my opinion that we got more performance out of 10s than any other team.

Over the summer we tested 10s versus 13s in back to back tests with r065 compound, Goodyear tires. Even with tuning for the 13s we never yielded any substantial gain that would clearly make the 13 a better tire choice. The 13s have a lower sidewall and therefore seem to have a higher cornering stiffness, i.e. the 10 require a higher slip angle to work best. For those teams that achieved major gains from 13s, I would say that the car was never set up correctly for the 10s or never had suitable compounds. Eric, it looks like you guys were running the 10 x 19.5 tire which has an enormous sidewall and is not nearly as stiff as the 10 x 18. This could be one of the reasons you guys saw such a performance gain with 13s.

As for tire choice we have run the Hoosiers, Goodyear R065, R095, and R115 in 10 x 18 x 8 and 10 x 18 x 6.5. The best all around performers for SAE events are the 10 x 18 x 8 R065 tire on a 10 x 7 rim front and 10 x 8 rim rear. We found that you can change the way the tire reacts by changing the size rim it is on. The R115 was an excellent tire for summer autocrossing and you can use it for countless events.

We have however decided to go to 13s for subsequent cars even though there was no appreciable gain.

In my experience some of the benefits of 10s are;

- Lighter - Although the gap in weight is negligible now, compared to when we went to 10s in 2000 you could save 8 lbs./corner.

- Cheaper - A wheel tire combo for 10s is much cheaper

- Less circumferential area - tire heats up quicker



Some of the problems;

- Wheels offered with sufficient offset are weak leading to the next problem

- Impossible to mount tires without annihilating the rims - we would set aside an entire day to mount tires by hand b/c this was the only way not to egg the rim

- Increased complexity of upright/brake package when using decent outboard geometry

- Uncertainty of continued production of suitable compounds

I hope some of our experiences help.

Noah Mckay
NC State University FSAE 2003

[Big Daddy]

On mounting tires on rims, most teams use two and three peice rims correct?? So why not take the wheel apart and assembe the wheel inside the tire, apply the sealant to the bolting surfaces and then seat the tire after the sealant has set up. Just thinking out loud, obviously you couldn't do that with douglas wheels but I have never bent a douglas by putting a tire on some of our other members have so its all in technique http://fsae.com/groupee_common/emoticons/icon_wink.gif

"A woman is a lot like a beer, they look good, smell good, and you would run over your own mother to get one." Homer Simpson

[NJM.]

Big Daddy,

Been there done that. You have to allow for another day as the silicon dries, and if you let the tire ride up on the rim and seal off the air before the silicon is dry, it will never dry. You have to stand on the tire and smash it (not good for the tire) so that it will ride on one rim half and then "peg" it in place with a screwdriver. Even after all of this work, we still never got the silicon to seal consistantly. We thought about grooving both halves and using an o-ring but never got around to it, and knowing our track record with breaking rims with no stress risers I didnt want to add one to the mix. No matter what technique we used, believe me we used a lot, we were never very successful with mounting 10s on a set of keizers. We had researced douglas but they did not offer them in the offset we required.

Good thought but it doesn't work all that great in practice.

[Big Daddy]

I had heard that Keizers were a little on the thin side. What offset were you looking for that Douglas couldn't do? Just more food for thought alot of ATV wheels out on the market have stiffing rings on the outer rim to help reduce flex, most of them are very thin and speed holed Like these from ITP


http://www.itptires.com/images/t9baja-close.jpg

"A woman is a lot like a beer, they look good, smell good, and you would run over your own mother to get one." Homer Simpson

[Jackson]

Douglas wheel would only make 10" wheels in a 3"/3" or 0 offset configuration. No special orders or anything -- that is the only one they sell according to their sales lady earlier this year. BUT they are CHEAP! only $30!!!!

Of course using 10" wheels you REALLY need as much offset as you can possibly get. We used 6" wheels with a 2" offset (or a 5/1 wheel). Ended up going with Keizers. They are 1/8" 6061 T6 rolled to shape. THEY ARE NOT ROUND!!! We machined hockenheim style billet centers, and they had to be custom fit to each wheel! The outside edges of the wheels are 0.200" out of round. Hopefully that doesn't make much difference...

Our susp geometry has 0 KPI and 47mm scrub. Steering may be a little stiff, but it is kind of hard to really determine that before the car drives. With 10" wheels corner deflection, the dynamic scrub radius will be significantly smaller than static (where it doesn't matter anyway!)

All this being said, the only reason we went with 10" wheels/tIres is cost. I thought we would be significantly more budget constrained than we were this year.

-Brian
Washington State U FSAE
"Suspension Guy"

[Big Daddy]

Now for something totally off the wall, Has anyone ever tried 8" rims???? I would imagine packageing would be a royal pain, just thought I would ask

"A woman is a lot like a beer, they look good, smell good, and you would run over your own mother to get one." Homer Simpson

[Big Bird]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Big Daddy:
Now for something totally off the wall, Has anyone ever tried 8" rims???? I would imagine packageing would be a royal pain, just thought I would ask

<HR></BLOCKQUOTE>

Concordia did 8 inch wheels on their little yellow snowmobile engined thing a couple of years back. There was a feature on it in Racecar Engineering, in their 2002 FSAE coverage. Tiny disc and caliper setup. Who makes tyres for something like that?

Cheers

Geoff Pearson
RMIT FSAE 2003

Design it. Build it. Write it off two weeks before the event.

[Big Daddy]

http://www.americanracetires.com/MCup.htm


I would imagine that they are tiny!!! It would be difficult to package but man could you save 15 lbs in a hurry.

"A woman is a lot like a beer, they look good, smell good, and you would run over your own mother to get one." Homer Simpson

[Big Bird]

Never heard of them. Does anyone else use this brand?

Cheers

Geoff Pearson
RMIT FSAE 2003

Design it. Build it. Write it off two weeks before the event.

[karter]

I've seen mini cup from Lows speedway, they use the front streight and the pit lane. Check out thier web page at http://www.mmraracing.com/index.html

[Foote]

hoosier makes some too.
http://www.hoosiertire.com/specota.htm
They seem to be really soft, too

Justin Foote
WWU FSAE

[Big Bird]

Thanks to everyone who contributed to this, and especially to those who forwarded good info privately. Most appreciated. We are more than happy to accept any further advice/criticism, but if you think the topic has been done to death on the forums then please feel free to use the private forums. I think I've figured out how to use them!

As for our tyre choice, it seems that our brand is going to be ultimately decided by what we can source promptly here in Oz. It seems one of the brands isn't going to be importing anything for a good few months, and we've been quoted $100 freight per tyre if we get them outside their normal container orders. Ouch! The joys of being on the wrong side of the world.

Cheers,

Geoff Pearson
RMIT FSAE 2003

Design it. Build it. Write it off two weeks before the event.

[wingman]

Hey everyone,

Great thread!! Funny how topics about wheels and tires start to sound like religious debates!!

Well Cal Poly Pomona has had 4 top ten finishes in the past 8 years and has used only 10" wheels for the reasons that NJM mentioned mostly....built also because we liked to go against the grain......

I am by no means a tire/suspension expert, but in my opinion, we sacrificed driver comfort for vehicle performance, and it showed in the endurance events with a progressive reduction in lap times that could be attributed to driver fatigue from heavy steering requirements.

I have not been involved for several years now so subsequent effort from the team may have remedied this problem.....

So how about the effects of wheel/tire combos on cars with aerodynamics??

[Big Daddy]

One question about the WWU wheel stiffeners. If you make your own hubs why dont you just make you hubs into stiffeners? It may end up being lighter. Just a thought.

"A woman is a lot like a beer, they look good, smell good, and you would run over your own mother to get one." Homer Simpson

[jack]

that is perceptive of you big daddy. the reason we do it like we do is because thats how we have done it...seriously though, we wanted to just keep with the standard bolt patern with four studs. i did notice this was a little pointless however, and plan to go to the F1 style one-bolt hub on the next car.

everything F1 is cool...

jack @ WWU
http://www.etec.wwu.edu/

[Big Bird]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by wingman:

I am by no means a tire/suspension expert, but in my opinion, we sacrificed driver comfort for vehicle performance, and it showed in the endurance events with a progressive reduction in lap times that could be attributed to driver fatigue from heavy steering requirements.

I have not been involved for several years now so subsequent effort from the team may have remedied this problem.....

<HR></BLOCKQUOTE>

Just a thought, Wingman - has Cal Poly ever tried running the car without the wings? I'd imagine that the extra downforce could have something to do with heavy steering, if that is the case. We haven't really found heavy steering to be a problem with the 10's.

Cheers

Geoff Pearson
RMIT FSAE 2003

Design it. Build it. Write it off two weeks before the event.

[James Waltman]

Big Daddy,
Combining the hub with the stiffener would be a bad idea. To keep the Douglas wheels you have to keep a standard bolt pattern setup. If you want to be able to change wheels then the stiffener/hub combo must unbolt from the wheel. A stiffener that is removable is severely compromised.

If we go with Jack's idea next year that probably means custom wheels and it doesn't matter anymore.

James Waltman
http://dot.etec.wwu.edu/fsae/
Vehicle Research Institute at
Western Washington University

[wingman]

Hey Big Bird

The heavy steering is a low speed problem due to the steering geometry with the 10" wheels and the available steering rack ratios combined with the scrub radius issues (if memory serves)

At high speed (i.e. a REAL auto-x course) steering input is lower and your only doing one lap at a time, therefore, not an issue

The wings are not a significant factor in this case, aside from the fatigue from all the lateral g's your pulling http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

[jonno]

just wanted to open up an old thread as I haven't really seen a newer thread on the 10" tyre topic...
so at FS rmit's 10's were fast enough. And the other 2 teams on 10's & singles came 4th & 5th (Delft & Tokyo) in the autocross. With rmit using goodyears, delft running LeConts and Tokyo using Hoosier, it can be assumed that this combination of tyre, engine & size of vehicle is fast. But do any of the 3 mentioned teams have any comparable data between the different tyres?
Also, I'd be interested to hear from delft about how they found the lower walls of the leconts. The reduction in rotational inertia must be quite beneficial (assuming the lecont's are similar construction to the goodyears & the hoosiers). Also, there has been a lot of differing opinions about sidewall flex. The leConts being 16" therefore only have a 3" wall, less than any of the others.
Finally, are there any other recomendable 10" tyres out there other than the 3 listed and can anyone come up with a comprehensive argument (other than comprimised packaging) of why not to drop to 10's from 13's?

[mech5496]

Back from the dead topic here! It just came to my attention that Avon has a 10" FSAE tire listed on their website for 2013. (http://www.avonmotorsport.com/resource-centre/tyre-applications/sae-formula-student) Has anyone used it? Any idea on the available compounds? Any experiences you want to share?

[acedeuce802]

Back from the dead topic here! It just came to my attention that Avon has a 10" FSAE tire listed on their website for 2013. (http://www.avonmotorsport.com/resource-centre/tyre-applications/sae-formula-student) Has anyone used it? Any idea on the available compounds? Any experiences you want to share?

I believe it was Toledo that used that tire this year. I talked briefly with them about it, and they said they weren't happy overall with the tire. We didn't talk much details about it, though.

[Z]

Harry,

My very UNreliable understanding is that those tyres are from the moulds originally made for the front tyres (x4!) of the Tyrell 6-wheel F1 car of 1970s? Mini Minor based race cars were common back then too, and since they came with 10" rims they may have kept the market going.

I believe nowadays they are mainly used in the British hillclimb scene, on the smaller bike-engined specials. I have seen them on some FSAE cars, probably from FSUK. They are quite easy to recognize, with big white "Avon" on the low profile sidewalls, and small OD (which I reckon is their biggest advantage, only ~0.4m, 16").

I understand (again, very unreliably!) that as primarily a "hillclimb" compound they have great grip from cold, great grip for ~1 lap, then overheat and turn to jelly. :(

Maybe try looking/asking on some British Hillclimb forums? Or, better yet, buy two, and burn rubber! :)

Z

[mech5496]

Harry,

I understand (again, very unreliably!) that as primarily a "hillclimb" compound they have great grip from cold, great grip for ~1 lap, then overheat and turn to jelly. :(

Z

That's what I am afraid of! As far as I know, Avon offers many compound options on all other tires, so a super soft and sticky compound would be ideal for accel/skidpad/autox while a harder compound might suit the endurance better. As far as I know teams are allowed to run only one dry compound, so we should test, find the best compromise and then compare to Hoosiers. Their smaller OD is a good thing for us (less rotational inertia, probably lighter, 7.5% shorter final drive (the car is directly driven from the motor) plus IMO they look better! The thing is that the lower overall diameter requires to lift the car by some 10mm thus affecting suspension geometry by a fair bit, but still we might be able to have some conclusions on how they perform. We most probably will buy a set but still I would like to have some insight from someone that has used them before buying! ;)

[Luniz]

We used to run Avon 13" tires until 2011 and we were quite happy after we played around with some different compounds. Avon is a very small company and they have no problem putting together a new tire from any existing components they have lying around. We ended up with the construction of a formula ford front tire with some special compound on it. They were happy to produce four sets/16 tires specially for us. So I suspect they could also make those 10" tires with different compounds if you ask nicely enough ;-)

What Z said about the supersoft compound is actually very much the case, we used that in 2009. Won two accel awards thanks to the sticky stuff but failed miserably in endurance in Hockenheim, because the tires literally disintegrated after 4-5 laps.