2025 : CM/FF Tires

[-pru-]

Folks,

Based on Jun/23 SCCA MAC (Modified Advisory Committee) / SEB (Solo Events Board) FastTrack comments, 2025 will be a milepost year for the SCCA Solo CM class; 6"/8"(FC/SR) wheels, Spec Tire, or status quo (i.e. no rules change). I've started this thread (and closed other related) to consolidate the discussion...

[racerjon1]

Question: Am I correct that we are just tossing around our ideas and thoughts here on ApexSpeed and individual letters need to be sent to the SEB/MAC? Nothing counts unless it is in a formal letter.

Quoting from the other thread, because it's a good question that we should all be aware of.

Technically - it should be in a letter to count. I can speak on Time Trials and Endurance Racing and say that those boards 100% lean as much into research from places like this as letters, but the older more traditional boards may not (I'm not on them) so - yes. Write letters.

That being said: We're a group of smart people, with decades of knowledge and experience that weighing the points here so the most number of people can write a letter hearing all sides and points of view, rather than just their own single feelings. We, as a group, also have the contacts and resources to learn and ask more people that don't know/understand/are invested enough to write letters.

Basically - we can sort of create an unofficial CM advisory committee. That through that knowledge and discussion can have a better voice.

Right now - without discussion - we all write in (what's that, 10 letters?) the MAC reads it, makes a decision and we get stuck with it right or wrong.

But - we've all brought up good points, and have even gotten to a place where each of us see the value in testing and trying stuff over just "fix it" and even letting the MAC understand that, and that we're willing to invest in the future of the class through those actions - can help them help us with the best path forward instead of "10 letters came in, six of them wanted this and so that's what we're doing."

So - discuss here, weigh options and data, then send letters.

[Lynn]

I am not ready to write a letter, yet. While I am strongly leaning toward 6 and 8 inch wheels, I am keeping an open mind. I want to see more results from testing other options before sending a letter.

[CM/FFdriver]

Hello All,

In reality we don't have a tire problem as much as people would want it to be a problem. We have a tire compound problem.

My understanding from Hoosier is they could make the R20 as a special order item only, no guarantee's BUT we would have to make the 64 tire quota every year and with only 11 drivers in 2021 and 12 drivers in 2022 unless we start having more "cars" competing then that possibility is very small.
Next is the Hoosier R60 cantilever rear tire and then the R60 FC front tire already being made for the CF competitors, they cost less than the R20 and readily available. We All wouldn't have to change a thing, maybe buy tire bags and be a little slower than we are now, still fun and like I said before, Running the R60's at the National's with the hot temp's and high ambient temp's they would be in their wheel house and them being co-driven most of the time anyways keeps them nice and hot, Most CM competitors would have to work on their setup's but isn't that the fun of these cars.

So I was thinking how this decision could be made for us by combining FM and CM into one class, If the R60 was the primary tire and it being the harder of the 2 compounds. The CM class could not compete with the FM class, case in point, the last 5 years a CM car had a faster time in 1 of those years .220, every other year the FM class winning car has been over 2.000 sec faster, but if we don't make the numbers in the next 2 to 4 years, Then....? where is the CM class going to be?

Now I'm all about going to the FC rim's, the 13x8 and 13x6 so then we can have an option to have a softer compound tire and there are some different tire manufactures with soft compounds also. It also gives us rain tires ( currently we don't have rain's for the FF) That to me is the future of CM going forward.

Ben

[ewcmr2]

Looking at tire things I found FC also has had tire issues. FC tires are still in production, but maybe not when you need them.
https://www.apexspeed.com/forums/sho...Late-September

[Ocho]

Hey all - just wanted to pop in and say I'm paying attention to both here and Facebook group.

Excited to see some of you in September - I'll swing by grid at nationals just so you can put a face to a name if we haven't met.

Brad.

[CM/FFdriver]

So, all this talk about the R60 rear tire being so bad is interesting because I ran this last weekend with AAS and it was 100 degrees, crazy weekend.

The numbers are this, with the R20 compound tires I'm within .200 sec of Andy Mckee (thats who I compared too) but this weekend I was 1.000 sec slower but it was very course dependent (super fast course), but with new R60 I thought I would be closer. No big deal on average I'm .880 sec slower.

I'm not trying to be an advocate for the R60 compound tires because I believe you don't have a site like Crows Landing where you can take full advantage of the R60 tires. Still not as fast as the R20 Formula ford tires and that's where the Formula continental rims and R20 compound tires would come into play, so all can play through out the Nation.

Ben

[ewcmr2]

But - we've all brought up good points, and have even gotten to a place where each of us see the value in testing and trying stuff over just "fix it" and even letting the MAC understand that, and that we're willing to invest in the future of the class through those actions - can help them help us with the best path forward instead of "10 letters came in, six of them wanted this and so that's what we're doing."
So - discuss here, weigh options and data, then send letters.

To further the data, I’ll bring a set or R888’s to Lincoln. I’ll have them on centerlock Van Diemen wheels and let people borrow them to try on the practice course. If someone has common 4 bolt wheels to share it would be good to swap tires to them and let more people test on their car.

[Jim Garry]

And keep in mind that Hoosier management will have an Autumn meeting to discuss continuing the soft cantilever tire.

[chrisw52]

And keep in mind that Hoosier management will have an Autumn meeting to discuss continuing the soft cantilever tire.

Best news about this issue I have heard all year. Let's hope for the best outcome.


If not, I am fully behind using FC rims & tires. Please don't liimit us to just the rear rim. That's a PIA..

[Gary Godula]

Hi all,

Dan Cyr and I have been testing a borrowed set of FC sized wheels and tires on my Reynard for a couple of events and have some data and observations to share. The tests were very positive.

First off, the tire specs. We are comparing a borrowed set of Hoosier FC 20.5x7 front/ 22x8 rear R60A new this season with 8 club racing heat cycles, compared with Hoosier FF 20.5x7 front/ 22.5x7.2 rear C2500 R25B 5 year old tires (my 2018 Nationals tires) with approximately 40 runs. We did not intend to test both a tire construction difference and a compound different, but that is all we had to work with.

The test vehicle: My long time Reynard 88F, which, despite my 9 year sabbatical from the sport, has been both autoxed and club raced bouncing between the two disciplines from 2000-2008 and then from 2017 to current. We used the chassis set-up from 2005 (the last year Nationals was at Forbes Field Topeka) which garnered 2 Pro Solo class wins, a Pro Solo Open Challenge win (Toledo), and 2nd (Dan) and 3rd place at Nationals, and 2nd in CML (Dawn Odoi). It is a good car.

Test Site: We attended an open test at Grissom AFB (all concrete, high grip, similar to Lincoln) in late June, at which we had approximately 1.5 hours of testing and laid down 20 test runs between us. We also ran the two sets of tires at the CAM Challenge event this past weekend at Grissom. I plan to test the tires on a low grip asphalt lot at a local test and tune this weekend.

The results: First off, the FC rear tires are quite a bit shorter than the cantilevered FF tires (69 1/2" circumference vs 70 3/8") which necessitated a minor rear ride height correction when changing tires. The rear camber was also corrected to be consistent between the two tires/ride heights at 0.8".

At the test and tune, we ran 4 sets of 5 hot laps, me driving the FF tires, Dan on FF tires, then Dan on FC tires, then me on FC tires. The track was quickly drying after a brief misting/drizzle. Weather was cloudy/partly cloudy, 78F. Track temp 85-90F. After learning the track on the first two runs, both Dan and I ran consistent 40.0 times on the FF tires, hot lapping the tires at 4-6 minutes between runs (start of lap to start of lap). The track was still slightly evolving from a brief shower just before the start of our testing. On the FC tires, hot lapping at a consistent 3.5 minutes run start to run start, Dan's last two runs were 39.8, which I matched by my 3rd run, with the final two runs at 40.1 due to a downed pylon in the fast 7 cone slalom.

Considering the track evolution, we consider the tire performances to be equal, but the following items must be taken into account:
We are trying to separate the tire size/construction from the differing compound and age of the tires.

Addressing the tire sizes and construction:
1. We see no real difference in performance between the tires. The FC rear tire is actually slightly smaller than the FF cantilevered rear tire, both in height and in width. Where the FC tire has the advantage is the non-cantilevered design actually plants the tire better. We actually preferred the feel of the FC tire on turn-in and in slaloms as the rear of the car felt more predictable with less lateral movement. There was no issue putting the power down with the smaller FC tire.
2. We did not make any chassis adjustments to compensate for tire performance. The cornering balance of the car felt the same between the tires. That said, the car had a slight understeer that we addressed at the CAM event that was not tire dependent.
3. The shorter FC rear tire changed the shift points slightly, allowed us to shift to 4th in a high speed section of the course, where we used 3rd on the FF tires. This could be an advantage or a disadvantage depending upon your gearing. We have the Reynard geared very tight with lots of overlap between gears.
4. Tire pressures: FF 15/17 stabilized, FC 15/16 stabilized. The tires grew 0.5 psi from the cold settings, and stayed there. Pressures were checked, but not reset, between runs.

Addressing the compound differences:
1. We are comparing newer R60 tires to 5 year old R25s. How many of us would consider 5 year old tires competitive on a national PAX index?
2. The R60 did not have the grip of the R25 at the beginning of the run, despite hot lapping the car as fast as possible considering the format of the test event. We were not able to take the first 2 turns at WOT on the R60 tires, but were able to take those turns easily flat WOT on the R25s. We believe that this speaks to the inability to get the R60s into their temperature operating window, even with hot lapping the car.
3. Due to time constraints, we were not able to get data of 5-15 cool down times between runs on either the R25 or the R60 tires. We were literally the last car to run at the test event. We suspect that the difference between the R25 and R60 compounds would be greater in that environment.
4. Tire temps were 125-130F as measured between runs on both the R25 and R60 tires.
5. Given the high grip nature of the track surface, the hot lapping nature of our testing, and the warmer summer temperatures, these conditions would most favor the R60 to perform similar to the R25. Lower grip surface, lower temps, and longer time between runs would most likely create a larger difference in tire compound performance.

Results from the CAM Challenge event: This past weekend we ran the CAM Challenge at Grissom, running the Sat morning session on the FF R25 tires, and the afternoon session on the FC R60 tires. We let both Robert Christmas and Dale Frame (Area 4 director who was on site for the AM) know our intentions. Temps were in the 80s, track temp in the 90s, with sun in the morning, and a partly sunny afternoon after a rain shower. Again, times were similar between the tires running with 2 drivers and 10 minutes between runs, both Dan and I in the 41 second range, but we were 4 seconds off the pace in the indexed Race tire class, and 2 seconds off of FTD of David Montgomery running his XP Porsche in the 39s raw. That speaks a little to our driving, and more to the overall grip level we had with 5 year or R25s and newer used R60s. We kept overdriving the R60s on corner entry and getting into the marbles, costing us time. There is no way that new R60s would have kept up with Dave on raw time, but new R25s would have. We had a small ignition cut out issue that made us decide to not take our final runs on Sunday as we did not want the car to die on course. (I am suspecting that my 20 year old soldered wiring job is starting to fatigue.)

Overall, we really liked the performance of the car on FC tires/wheels, and those tires/wheels did not force any changes to the car other than a simple ride height correction. The R60 compound, however, was given the best opportunity to outperform 5 year old R25 tires, and it only matched it. Based on my experience being forced to run R60 compound in club racing, I expect the R60 performance to degrade much more than the R25 in anything less than ideal conditions similar to what we tested in.

I am going ahead with again recommending the allowance of the FC sized wheels and tires for the class for the following reasons:
1. The wheel and tire sizes are used in several club racing classes (FC, S2000, F1000, etc) and therefore the tire options should not be in danger of shrinking or being eliminated.
2. There is no real change in the vehicle performance envelope and thus the PAX does not change.
3. Only rear wheels need to be acquired, which should be available used for almost every vehicle eligible for the CM class. (Remember, wheels are cheap, tires are expensive.)
4. Allowing wheel/tire options are consistent with previous modified class rules changes and does not devalue the CM cars nor prevent them from moving back and forth between autox and club racing nor between different sanctioning bodies. (Remember the allowances granted to create the FM Solo Vee.)
5. In our opinion, the FC wheel/tire combination actually drives better than the FF tires do.

I am also writing against the R60 spec tire for the following reasons:
1. Forcing a spec tire or a tire rule would create a new precedence within the modified classes which is outside of the objective and the spirit of the modified classes.
2. A spec tire would immediately obsolete every tire that we have in our inventory, costing all of us over $1200 per set to replace. Money that we could never recoupe by selling the old tires. This would cost us much more money than a couple of wheels.
2. The PAX index would need to be greatly adjusted and would never be correct for any given weather and environmental conditions, thus handicapping all CM classes by rule in any combined class situation, both Nationally and locally.
3. A spec tire would intentionally reduce the performance level of the CM cars, which creates a dire issue of class sustainability. If the CM class is restrained by tire, as some have proposed, then the FM class would most likely have a higher performance level than the CM cars. Considering that the initial purchase price of a decent CM car is 2-3 times the initial purchase price of an FM car, and the FM car has higher performance and would be more enjoyable to drive on a non-restricted tire, why would anyone want to buy a CM car? Ultimately, the CM class would be eliminated and merged with FM, and FF would be uncompetitive in that class.

I am concerned that, after a discussion with Dale Frame at the CAM Challenge, he stated that they were seriously considering the spec R60 tire option (mostly likely with a lot of prodding from Hoosier). If that is the case, then anyone who is not in favor of that needs to write a lot of letters, to the MAC, the SEB, your area director, and anyone else who matters. I still feel that any tire or wheel allowance decision should be made by the class members, not the SEB, the MAC, or the tire suppliers. We are talking about the survival of the class, and the wrong decision will most likely lead to the demise of the class. Do we want that to happen? Remember, it is not in the best interest of the MAC or the SEB that the class survives as both the MAC and the SEB are under constant pressure to reduce the number of classes within the solo program. This would just be an convenient way of moving forward toward that target.

As stated above, we plan on testing the FC tires/wheels on a local asphalt lot for more data. I will let everyone know what we find. If anyone is in the Detroit area this Saturday (for anything besides the Dream Cruise), you are welcome to join us and drive the car.

[ewcmr2]

I am also writing against the R60 spec tire for the following reasons:
1. Forcing a spec tire or a tire rule would create a new precedence within the modified classes which is outside of the objective and the spirit of the modified classes.
2. A spec tire would immediately obsolete every tire that we have in our inventory, costing all of us over $1200 per set to replace. Money that we could never recoupe by selling the old tires. This would cost us much more money than a couple of wheels.
2. The PAX index would need to be greatly adjusted and would never be correct for any given weather and environmental conditions, thus handicapping all CM classes by rule in any combined class situation, both Nationally and locally.
3. A spec tire would intentionally reduce the performance level of the CM cars, which creates a dire issue of class sustainability. If the CM class is restrained by tire, as some have proposed, then the FM class would most likely have a higher performance level than the CM cars. Considering that the initial purchase price of a decent CM car is 2-3 times the initial purchase price of an FM car, and the FM car has higher performance and would be more enjoyable to drive on a non-restricted tire, why would anyone want to buy a CM car? Ultimately, the CM class would be eliminated and merged with FM, and FF would be uncompetitive in that class.

Remember, it is not in the best interest of the MAC or the SEB that the class survives as both the MAC and the SEB are under constant pressure to reduce the number of classes within the solo program. This would just be a convenient way of moving forward toward that target.

1) I’ve not seen the R60 and spec mentioned together by anyone in a leadership/advisory position.
2) Whatever is decided, you have all of 2024 to use up tire inventory.
2) If a clearly slower spec tire is mandated, RRuth can make up a number, just like he always has.
3) CM is already slower than FM. Maybe someone wants a CM car so they don’t have to work on or listen to an FM all weekend. (Sorry Brad!) If members only wanted to go as fast as possible for cheap we’d all be in KM. How many Street & SSC type members could afford a $8000-25,000 CM car if competitive tires were less than a $1000 a year? A year, not a weekend or two…


The job of advisory committee members is to (be experts in the category) and INCREASE participation in the category. No one on the MAC is looking to kill CM. If a class goes away it’s because they’re wasn’t member support/participation for it.

[Jim Garry]

Potentially, the adoption of the R60 is something that I believe would appeal to the SEB. It seems simple. No new wheels needed. No suspension modifications because of the size of street tires or their need for camber. Just slap them on. Never mind that except for some parts of the country during some parts of the year, the compound will result in sideways and understeering cars and make them not fun to drive. I pray the SEB doesn't do that to us. Indeed, as Gary stated, it should be the class that decides the next direction, if Hoosier discontinues the soft cantilever.

And regarding use of street radials, that's also how I feel about them. Although I intend to test them just to be fair and open, from an objective standpoint it seems likely they will never heat up. Several tire engineers have said so. One said it might be OK but he is a road racer and I don't think he had in mind how little heat we generate. Even if street radials did heat up they wouldn't be as much fun.

"But it would be the same for everyone!" Yup, it would. It would be a negative experience. Very little grip results in drivers just completing basic navigations of the course. Just getting around. No becoming one with the car. Just get it through. The best way to kill a class is to make its cars not fun to drive.

The cost of street radials would be pretty minimal. They'd last for years because they're designed for 3000 lb cars. Our 1100 lb cars would not use up much tread or put the tires through heat cycles. But fun? I don't see it.

Do I like spending money on tires? Yes and no. But I can say with complete honesty that I love the way our cars can be driven on them. And even in the street category people are spending a sh-t load of money. And I don't believe there are droves of people not joining CM because of this issue.

I'd happily find some 8" wheels to run the FC rears on and enjoy a real race car on rubber they were designed for. I'd continue to use the 5.5" wheels for rain tires.

And keep in mind that Hoosier may decide to continue the soft cantilever. And if that does happen I would hope that those who support the Toyo idea wouldn't try to campaign against the status quo of what we've been using since the class started in 1990.

[ewcmr2]

I am concerned that, after a discussion with Dale Frame at the CAM Challenge, he stated that they were seriously considering the spec R60 tire option (mostly likely with a lot of prodding from Hoosier). If that is the case, then anyone who is not in favor of that needs to write a lot of letters, to the MAC, the SEB, your area director, and anyone else who matters.

I’m guessing there was a communication misunderstanding, two BOD members confirmed they are not “seriously considering the spec R60”.

[Jim Garry]

I’m guessing there was a communication misunderstanding, two BOD members confirmed they are not “seriously considering the spec R60”.

OK, but what about the SEB?

[ewcmr2]

OK, but what about the SEB?

I haven’t heard anything from the SEB, so they certainly aren’t pushing for any outcome at this point.

[Dayle Frame]

I am concerned that, after a discussion with Dale Frame at the CAM Challenge, he stated that they were seriously considering the spec R60 tire option (mostly likely with a lot of prodding from Hoosier).

As the Area 4 Director, I try to stay out of public discussions but a constituent emailed me and asked about this post from Gary.

Gary….you dramatically over read what I said. I am a liaison with the CRB. I’m NOT a liaison to the SEB so I have NO sway with that group. No CRB member or liaison have had contact with Hoosier on this topic. Please do not speculate or try to interpolate a brief chat we had while I was visiting the CAM Challenge. I was there merely as a spectator and NOT as an official in any way.

To shed light on the conversation for the readers of this thread…….I told Gary that one suggestion (among many) for the SCCA might be to move to a tire like vintage groups and other countries use for FF. That’s all I said….nothing more. We have NOT acted on this issue in any way.

This was a part of a long term, strategic discussion on how we massage Club Racing for the future. Under the guidance of John LaRue, the CRB has been given the opportunity to investigate how we adjust the Club Racing program to make it stronger as we move forward.

Dayle Frame
Area 4 Director (IN, KY, MI, OH, WV)
EVAC Chair, CRB Liaison

[Jim Garry]

Thanks for Dayle's post. I know he wasn't advocating use of vintage tires for CM, but allow me to provide my thoughts on use of such a tire for CM use.

We'd have the same issue as we would if we used the R60 or Toyo ... lack of run time to develop tire heat in the autocross environment. The cars lose their sharp, and fun, handing characteristics.

The least change in handling would result from being allowed to use FC wheels. I don't care if it's just the rear or the rear and the front. Our cars would continue to be fun to drive and would provide the crisp, exceptional handling we have had since 1990.

If we are forced to use vintage or street radials or Hoosier FF spec radials (R60 compound) or R60 in our current sizes, the cars would lose their exceptional driving characteristics. If we are going to have to slide around at speeds close to the lower Street Touring classes, why do it in a Formula Ford which requires much more maintenance and set up? This is the part I don't get. Why lower the Formula Ford experience? It's not only a matter of speed, it's the lack of fun at the new and lower potential. Just do it in a cheaper car which will likely feel better because the 200 tread wear tires are perfect for those cars.

[griceiv]

OK, but what about the SEB?

no R60 agenda from the SEB either. The goal of the SEB is to increase participation and I (personally) don't see how a lower performance tire being mandated would do that. I think test data like Gary and Ben (and soon to be Eric) have shared with the community goes a long way towards supporting a well informed decision on the way ahead.

-Marshall

[ewcmr2]

Mounting tires for Nationals, apparently the R888r is a wide 205…

[ewcmr2]

Front is also surprisingly similar width, but taller.

[-pru-]

Via R&S:

2024 CM Rear Tire

Pre-Orders for the CM Rear Tire is open until 2/1/2024.

If we get enough pre-orders (60 or 108 Tires), Hoosier Racing Tire will build them.
This is the only planned build for the 43305 in R20 Compound, CM rear tires in 2024.

Use our handy Pre-Order form at: https://www.rsracing.com/cmreartiref...KT_6HzfcoHOED8

Time for the class to "put up or shut up" w regards "qualifying" tires ....

[Ocho]

Posted by Sonja on FaceBook:

Just a reminder that the Feb. 1, 2024 deadline is approaching. We have gone over the 60 build count and need to get to the next build size of 108.

Please note that this is the only build for the CM rear tire for the year. Hoping to have the tires built and ready to ship in March to start the racing season...let's go racing!!

https://www.rsracing.com/cmreartireform.aspx