Track day rims

[BlueStreak]

Im thinking of picking up a set of 17x8 or 17x8.5 rims over the winter to use for track days. Can you recommend anything? At this point, I don't care about weight so I don't want anything fancy. I'm just looking for something that works and isn't very pricey.

I have a MS3 if that matters.

[mleblond]

rota's FTW inexpensive and light. don't go wider than 8"

[BlueStreak]

Why shouldn't I go wider than 8"?

[mleblond]

Why shouldn't I go wider than 8"? 8 inch sticks out a bit already. Depending on your suspension it may catch the fender on bumps. Im no expert tho, pm allen at simply tire he may be able to explain more on that. Im running 17x7.5" for track on 235,45,17 on my MS3

[Fobio]

with an 8" wide rim, I'd go 245 width, which may be pushing it already...at 8.5" you HAVE to go with 245+ for proper fitment...you can stretch your tire but it's definitely not recommended for track work...

personally, I'm also looking for for a 17x8" track setup...and run 245/40/17 or 235/45/17, depending on price...we should be looking for +48 to +50mm offset...anything over 245, and you'll have to roll your rear fenders, unless you run a reverse-staggered (front wider than rear) setup, and that means you can't effectively rotate front and back tires...

[BlueStreak]

Wouldn't running wider fronts make the car very twitchy?

[Fobio]

Wouldn't running wider fronts make the car very twitchy?

for bad roads like downtown TO, yes...but for the track and the kinda power you're putting down, wider the better...Cobb runs 255/35/18 on 8.5" rims, with rear fenders rolled...

in terms of cheap light rims, rotas are first to come to mind...and over the yrs, quality issues have been worked out...having said that, I wish for a set of Enkei Rpf01 or some JDM rims but bling $ can be better spent on going faster so that's a personal choice...

[BlueStreak]

Do you know of a place that sells Rotas? I contacted Allen from Simply Tire and he doesn't carry them.

[doughboyr6]

there's one set of enkeis that i see a lot of tuners use on EVOs...RPf1

[condor888000]

RPF1's are light and look awesome too. Another similar set would be Kosei K1 TS. Both are around 15-16 lbs a corner for 17x8.

Can find either for $200-250 easy, cheaper if you really look.

For Rota's, Track Werks (http://www.trackwerks.ca/) carries them. Problem is they're up here in Ottawa...

[p-o-g-i]

Enkei's!!!!

(rumour has it too that pogi is selling a set posted in the For Sale Forums :chuckle )

[BlueStreak]

What's the price range for some 17x8 Rotas? I can't find any places online with CDN pricing...

[dentinger]

allen quoted me around $230ish ea for 17x7 ish

[condor888000]

For Rota's? Christ, order from Wheeldude and bring them over the border yourself at that price.

[dentinger]

thats wat i originally thought. buts subydude sells em for around $600ish, and shipping to canada is $200, and thats all US currency. so unless im in the states for a bit, there's no point.

[condor888000]

I keep forgetting all you poor Toronto guys. I'm 45 minutes from the border and so my plan is to bring across anything expensive shipped from the States.

[Wild Weasel]

I'm pretty sure my winter wheels are 17 x 8". :) Running 225/45/17 on them with no issues, of course I'm not really putting much in the way of lateral G's on them.

[mleblond]

I paid less than 400$ for a set used. Just keep an eye out on boards and kijiji, craigs list. No use to buy new rims for the track...they WILL get scratched.

Plus the season is almost over

[Marsh]

with an 8" wide rim, I'd go 245 width, which may be pushing it already...at 8.5" you HAVE to go with 245+ for proper fitment...you can stretch your tire but it's definitely not recommended for track work..

Really? I know lots of guys in the miata community running 225's on 9" wheels. BTW stretching a tire actually improves performance. The manufacturer of any given tire will list a range of wheel fitments. You can usually go half and inch bigger without sweating too much.
http://i203.photobucket.com/albums/aa118/P90Puma/timmies_shoot_07-27-08034.jpg

[Fobio]

Really? I know lots of guys in the miata community running 225's on 9" wheels. BTW stretching a tire actually improves performance. The manufacturer of any given tire will list a range of wheel fitments. You can usually go half and inch bigger without sweating too much.

Marsh...I hate to call you on it...but how do you figure that stretching a tire to the extent of 225 on a 9" improves performance for a MS3? Yes, the MAXIMUM recommended sizing for YOUR particular application would be 225/40/16 and yes it COULD fit on 16x9", but on a much lighter (~2000lbs) RWD and more balanced (50/50 weight distribution) car...this is for recommended fitment of 225 between 7.5" to 9"...where 9" is the maximum...are you saying that 225 on a 9.5" is alright?

For the MS3, and the kinda power (250+ WHP/WTQ) it puts down on the front wheels AND the weight (~3200lbs., 60/40 weight distribution) of the vehicle, stretching a tire like going 215's on a 8" wide rim is pushing it...and I don't know many guys running 17x9" with 215 or 225...most aggerssive wide stance I've seen on a MS3 is 17x9" running 235/40/17, and I think that's stretching it...the rears actually stick out of the rear fender a tiny bit...for reference, he says he doesn't rub http://www.mazdaspeedforums.org/forum/mazdaspeed-3-6-general-lounge-new-member-welcome/8489-17x9s-wont-fit.html

But I digress, cuz in AutoX situation, where speeds are lower you may get away with stretching a tire...but if you go on higher speed track, I'd wonder about the safety of a tire stretched to the max beyond proper and recommended fitment...all the MS3 Time Attack cars I know of fit as much meat as they can in there (as WIDE a tire as possible), without creating bulge/bubble or rolling the tire...

EDIT: Why would you want your tires to do this \__/, when you can get them to do this |__|, and without doing this /__\?

[Marsh]

A tire that does this \_/ is faster than a tire shaped any other way because of the way that it flexes. Think of unequal length arms on a double wishbone, or double a-arm suspension. The arms are never parallel. This generates camber change with travel. The result is that the roll camber of the car can be compensated for. I'll come back to that in a minute.

Now as for camber what I lot of people don't realize is that camber generates cornering force all by it self. Ideally you want all kinds of negative camber in corners. But the reduces grip in a straight line (braking and accelerating). Thus you try (and macpherson strut cars usually fail miserably) to create a suspension system that dynamically gives you the best of both worlds. What works best will depend on what the car is used for.

No what people don't usually think about is tire camber. That is that even if the wheel is straight up and down the tire can be cambered into the corner. Some manufacturers make their tires this way by making the outer diameter of the inner shoulder larger than the outer diameter of the outer shoulder. It does work to an extent, but again the loss of straight line grip is an issue. Now besides construction there is also flex, and remember, all pneumatic tires are in a state of flex ALL the time. Think of the side wall of the tire like the tires internal suspension. The air is the working fluid, but the sidewall defines the shape. Now lets use our initial model as the theoretically ideal "perfect" fit, where the side wall is verticle when the wheel is verticle. Now for the car lets assume a kart with no suspension and zero camber. This wheel should theoretically stay perfectly verticle in a corner since there shouldn't be any roll. BUT the tire will still flex.

In a corner (car travelling away from you and turning right) the tire will move from this |__| to this \__\. Not bad. The contact patch is still nice and level and in contact with the road. But there is no camber, which would actually improve cornering grip.

Now lets consider the universally recognized bad situation of a wheel that's too narrow. Same corner the tire will go from this /__\ to something like this |__\. Of course I can't draw what will actually happen, but I think you can understand that the right sidewall is in tension and will lift the right side of the tread off the ground. This means loss of grip. Not only that but the camber is now in the wrong direction. This will generate a lateral force, but one pushing the car out of, not into, the corner causing a further loss of maximum cornering force.

Now consider the wider tire: When mounted it would look like this \__/. If we take our right turn then it deforms to something like this \__|. At first glance this looks just as bad as the second scenario. BUT the camber is now correct. This will lead to and increase in the peak cornering load of the tire.

Now how much stretch is too much will depend on the car, the tire and the total available grip. The affect we're taking advantage of is called "camber thrust" by most. The amount of camber thrust generated for every degree of camber angle depends on the tire. I recently was given data comparing the Toyo R888 and Toyo RA1 in which it was clear that the R888 generates a good 250N or more additional force than the RA1 at high camber angles.

Now this isn't even considering the fact that the VAST MAJORITY of street cars do NOT generate enough negative roll camber in corners to compensate for body roll. Using tire stretch to get some tire camber will often result in correcting the camber to being less obviously wrong than actually getting into the true negative range.

If you want some history behind this do some searching on F1 tire in the 70's. In a matter of two season the wheels and tires went from being skinny, to the widest they ever were. This is because the team engineers realized that a wider wheel worked better. So every time the tire manufacturers (there was a tire war at the time) gave them a new tire to fit their new wider wheels. They would get the wheels made wider again to improve cornering. When the tire manufacturers saw the new wider rims they though "hey we didn't know you could get wheels that big, we'll make wider tires." and for two years things snow balled into some monster rubber.

Now obviously wider is usually better for tires, but it's also true of rims. So what's you're limiting factor? Can you not fit a wheel any wider than a certain amount before hitting the suspension? Or is it the tire width that's limiting you? In either case you still push the other to the limit to maximize grip.

Of course there is the concern, by people that have never done it, about un-beading the tire. Yes it's a risk, but it's a pretty minor one. Do the math on how much force is holding that bead on. It's simple. Calculate the surface area of the tire side wall and multiply by the air pressure to get the force. If you can get that much cornering force out of one tire I'd like to see it! As long as the tire is firmly on the bead and not statically pulled away then I'd feel perfectly safe driving that tire hard. As for quoting you a number, as I stated I would never condone going more than 0.5" more on wheel width than the factory recommendation. Those recommendations are using a fair amount of safety factor.

Oh and BTW a 215/50-13 Kumho V710 is over 8" bead to bead sitting at rest. That means you're actually bending the tire IN to mount it on a the factory recommended 8" wheel. They tend to work best on around 9". But at 9" you have to invest in very light wheels. You will usually hit a performance window were the additional wheel weight is not worth the extra width long before you're pushing any safety limits.

Oh and good reading on stuff like this can be found in Caro Smith's "Tune to Win" and Paul Haney's "The Racing & High-Performance Tire". The former is more informative for someone actually looking for information to use tuning a race car and the latter is more anecdotal information. I would highly recommend "Tune to Win" to anyone looking to understand more advanced suspension theory in relation to maximizing performance. Of course "Race Car Vehicle Dynamics" is the bible of the industry, but I wouldn't recommend it to anyone without a year of engineering or at least some dynamics courses under their belt.

[Marsh]

Oh and I only do these lessons once on any given web-board so please FAQ it so I don't have to keep searching it out every time some newbie thinks they know everything.

Thanks.

[allen@simplytire.com]

Marsh, you've made some very true points and almost everything you've said is pretty much dead on... but what Fobio is saying is true as well, and he's hardly a newbie... it seems to me as if your experiences are more with RWD vehicles rather than FWD vehicles... Fobio is simply saying that for a lower HP vehicle like the MS3, leaving aside the fact that it would rub (guaranteed), there really is no gain or benefit in going with a 17x8.5 or 17x9 on these cars...

I currently track an AWD S60R and find that a l_l sidewall works far better than the 245's I had on before... my 245's were a little bulgy and I felt sloppy on the track... but I'm no pro... I just know tires.

I hope you don't mind, but I've copied and pasted your extremely well-written response to my notes and plan to use it as it was extremely informative !!!

To the original poster... I don't sell Rota's anymore because of their crappy customer service and horrible Canadian distribution. Everytime I've ordered a set for a customer, they've come later than they were supposed to. I will PM you a price on the Kosei's... and look into other alternatives for you... do you know what size tire you wanted to run?

[Fobio]

Now how much stretch is too much will depend on the car, the tire and the total available grip. The affect we're taking advantage of is called "camber thrust" by most. The amount of camber thrust generated for every degree of camber angle depends on the tire. I recently was given data comparing the Toyo R888 and Toyo RA1 in which it was clear that the R888 generates a good 250N or more additional force than the RA1 at high camber angles.

^^^this is what I was referring to specifically...how much stretch is too much stretch and in what application is stretch safe and when does it become UNSAFE...also, the benefits and where the envelope is depending on the car's weight distribution...ALSO, due to let's say my RT-615's being sidewall-reinforced, will the benefits of stretching the tire to achieve the same level of "crispness" is necessary with today's tires...

I very much appreciate the points made by Marsh and Allen...can we move this thread over to the tracking section to continue this discussion?

[Marsh]

Marsh, you've made some very true points and almost everything you've said is pretty much dead on... but what Fobio is saying is true as well, and he's hardly a newbie... it seems to me as if your experiences are more with RWD vehicles rather than FWD vehicles... Fobio is simply saying that for a lower HP vehicle like the MS3, leaving aside the fact that it would rub (guaranteed), there really is no gain or benefit in going with a 17x8.5 or 17x9 on these cars...

I currently track an AWD S60R and find that a l_l sidewall works far better than the 245's I had on before... my 245's were a little bulgy and I felt sloppy on the track... but I'm no pro... I just know tires.

I hope you don't mind, but I've copied and pasted your extremely well-written response to my notes and plan to use it as it was extremely informative !!!

I wasn't referring to Fobio as a newbie. I was referring to future posts, where a newbie is someone that wasn't around during this discussion.

Although that said I do think of Fobio as a newbie. I've been involved in motorsports since 1998 when I started with a 1998 Honda Prelude SH. I've only recently (3 years) started competing in a RWD car. But frankly my competition experience is not what I consider my source of knowledge. While working on my engineering degree I worked on UWO's forumla SAE car
http://www.engga.uwo.ca/sae/News/index.php for four years where I was involved in the design and building (from scratch) of four purpose built open wheel race cars, culminating with my position as the lead suspension designer in my graduating year.

When I say I've forgotten more about vehicle dynamics than most people will ever know, I'm not exaggerating. The amount I've forgotten since graduating, because there simply isn't that much you can change on a purchased car and I don't use the knowledge anymore, is more than even most competition drivers will ever know.

Fobio, as for how much is too much it takes experimentation to find what does and does not work. But from those I know that have actually done that experimentation the limit of performance improvement seems to be around 1" more than the ideal size recommend from the tire manufacturer. Now how much the maximum recommended size varies from the ideal might be different. Of course the tires have also changed since I've personally last seen any real comparison.

But never the less the reason for my orginal response to this thread was this. 225 is perfectly safe on an 8" rim. 245, will likely give more grip and be faster (assuming the same diameter), but you (Fobio) seemed to be implying that it wasn't safe to mount a 225 tire on an 8" rim and I'm saying that's not the case.

[Fobio]

Fobio, as for how much is too much it takes experimentation to find what does and does not work. But from those I know that have actually done that experimentation the limit of performance improvement seems to be around 1" more than the ideal size recommend from the tire manufacturer. Now how much the maximum recommended size varies from the ideal might be different. Of course the tires have also changed since I've personally last seen any real comparison.

But never the less the reason for my orginal response to this thread was this. 225 is perfectly safe on an 8" rim. 245, will likely give more grip and be faster (assuming the same diameter), but you (Fobio) seemed to be implying that it wasn't safe to mount a 225 tire on an 8" rim and I'm saying that's not the case.

Specifically, I don't see why running 215 or 225 on a 8" rim when running a 235 on 8" is ideal FOR THE MS3 and I am not doubting whether a 225 on a 8" rim is safe, I run 225 on 7.5", so I know. BUT you said specifically:


Really? I know lots of guys in the miata community running 225's on 9" wheels. BTW stretching a tire actually improves performance. The manufacturer of any given tire will list a range of wheel fitments. You can usually go half and inch bigger without sweating too much.

I'd DEFINITELY RECOMMEND AGAINST RUNNING 225's ON A 9" RIM, and is specifically asking you to clarify if you're recommending this as an improvement and how does it apply to a Mazdaspeed3, which is what the OP has asked for as a recommendation. If you see and know of benefits of running this setup on a Mazdaspeed 3, then I'd ask for your clarification...

As well...if you recommend this for a Miata, well then I'd still ask for you to clarify why running 225's on a 9" rim is safe and enhance performance as you've stated.

What I'm specifically stating is that with TODAY's technology and updated know-how, stretching a tire to achieve the level of crispness you sought with shitty outdated street tires from "back in the day" is not as necessary with today's updated tire technology and much stiffer sidewalls...

Please qualify your statement as to why a 225's on a 9" rim is safe, recommended and improves performance on a Mazdaspeed 3 as per OP's question, not a Miata. And if it's ok on a Miata, then why? And how can that experience be translated to fitting a RECOMMENDED AND SAFE TRACK SETUP FOR THE MAZDASPEED 3.

[Marsh]

Why are you so hung up on "on a mazdaspeed 3". The car is not important. The drive configuration is not important. The geometry, loading and tire characteristics are important. The Mazdaspeed three is an economy sedan. It has a great engine and the springs and shocks are much better than the base 3, but no matter how much money you through at it, it will never stop being a family car. In essences it will never have enough dynamic negative camber for competition purposes without completely replacing every suspension link (because the struts are too vertical). This means it will benefit MORE from the added dynamic camber of a wider rim.

No as I stated will a 225 tire be faster than a 235 or 245 tire? On a road course highly unlikely. Temperature is key to getting a tire to work better and the speed three is heavy enough and has enough power to heat a bigger tire than 225. I would think 245 front and 225 rear is the optimal setup.

That said running a 245 tire on a 7.5 rim might not be faster than running a 225 on a 7.5 rim. The negative side effect of the tread distortion and tire flex on that small a rim will not make up for the wider tread. Not to mention that the wider tire is heavier (and competition tires are a lot heavier than street tires when you're talking street legal competition tires, which I assume we are).

Now 8" rim it's debatable. 9" rim then obviously a 245 is going to be faster. But can you fit that tire under your fender? Can you fit that much wheel under your fender? Does a 245 tire come in the tire you want? If no and you're stuck with a 225, then you want to go as wide as possible. Now if you're stuck running a 225 tire then 8.5 is definitely going to be faster than an 8" tire (my opinion). Will a 9" wheel be faster than an 8" wheel? Well on the previous generation Hoosier DOT-R's yes. Those tires were notroiously wider than their stamped sizes. On the new Hoosier A6/R6 DOT-R, possibly. The new tires are known for being hit or miss on actual width so you should lookup what Hoosier says they are to see how much stretch is possible. BTW the new "todays technology" hoosiers are not really any faster than the old ones. But they are cheaper and last a little longer. Mostly because Hoosier added steel to the carcass for the first time. With a Kumho V710, again referrence the manufacturers width numbers. How accurate the width is to the quoted tread width varies from tire to tire. Often to suit the target market of the size (for example virtually every DOT-R manufacturer makes a 185/60-14 tire specifically to fit a stock first gen miata wheel for ES autoslalom in the SCCA. It's that big a market). 225/15 tires are usually targeted at smaller cars running bigger wheels (mazdaspeed miata etc.) and don't have as stiff a side wall so that when heavier cars use them (my Prelude I ran 225/50-15's on 15x7's) you have to run more tire pressure to get them to work. I've heard the V710 was worse for this, but I don't have personal experience because I switched to smaller cars the same year it came out. On the other hand a 225-17 tire is meant for larger cars that must run a 17" wheel (either to clear huge brakes or because the rule book ropes them into using a stock wheel) the side walls are built a little stiffer since the cars using these tires tend to be a little heavier.

Now justifying that a 9" wheel is better for a 225? I can't personally I haven't seen testing for this. I just used it as an example that it can be done (with the Hancook RS2 btw, which is a current hot street tire. I set FTD at the last WOSCA club solo2 on a set of 195 RS2's in the dry) safely. The added weight of the 9" wheel over an 8.5" wheel might not be worth. That said I'm not aware of any 15x8.5" wheels available other than multi-piece custom for huge dollars. So it's a choice between 8" or 9". BTW the 9" wheel I'm reffering to was really made to fit the 275/45-15 Hoosier which could actually use an even larger rim. The 225 on 9" wheel is just a badass looking and good performing street tire setup.

Oh and BTW


What I'm specifically stating is that with TODAY's technology and updated know-how, stretching a tire to achieve the level of crispness you sought with shitty outdated street tires from "back in the day" is not as necessary with today's updated tire technology and much stiffer sidewalls...

Common! You've meat me do I look 60 years old to you? Today's much stiffer side wall? The stiffest sidewall DOT-R I've ever seen was the previous generation BFG G-Force R-1, which was so horrendously terrible when it came out in 1999, that they stopped making it shortly after because the Kumho V700 Victoracer had compeletely rendered it obsolete the same year. Then the even newer V70A Ecsta never really caught on because it had an even softer sidewall that didn't work for 3000lb+ cars. As for street tires the Falken Azenis has been out for years and was only really de-throned as the top street tire last year by the Bridgestone RE01R, which I've heard is softer (never owned either tire) and this year there are several new competitors (Toyo and Dunlop notably) that have upped the anti with competitve STS street tire competitors. Hell, Toyo still sells the RA1 which has been in production since '98 if not before.

[Marsh]

Oh sorry, I spoke too soon. Apparently a few guys have reported that the 225/50-15 Nitto (NT01 I think?) is faster on the 15x9. In fact it's wide enough it's not much stretch at all: http://www.949racing.com/server/15x9_6UL_nickel_6.jpg

[silvermist99]

The Mazdaspeed three is an economy sedan. It has a great engine and the springs and shocks are much better than the base 3, but no matter how much money you through at it, it will never stop being a family car.

:pop no comments from me but subscribing to this thread!! :bana2