C Mod Tires - Bad News

[CM/FFdriver]

Jim, appreciate the reply.

Question: Wouldn't allowing 6" and 8" wheels this year, with the appropriate FC tires, be seen as an advantage to those who are set for the remaining year using the current configuration? I think we all would be shocked if it didn't help some. I find it ironic that decades ago, the day after I purchased the Royale S2 for CM, Fastrack arrived with a proposal to kick S2's out of CM primarily because of the following advantages: (1) Better HP to weight ratio and (2) 6" and 8" wheels versus 5.5" wheels. Now all you FF guys are telling me size (wheel) doesn't matter? LOL

No win solution for this year. My gut tells me getting wider wheels ASAP could be an issue and expensive for some.

Craig

Hello Craig,

Here is the info that I've come up with when it comes to the 2 different rims and tires. I've seen 4 sets of FC rims for sale between 1200$ to 1600$ and there's an event at Sear point raceway in Sonoma this weekend and I may go there and ask around and see the FC contingent for their rims could be for sale.

Let me give you facts about the 2 different rims and tires, the rims and tires we are running now are weighing in at 9 lbs and the tires are 16.5 lbs. I just texted Brad at Primus and he said the FC rims weigh in at 11.5 ea I don't have info about the FC tires but I'm betting about the same at 16.5 lbs so the difference is 2.5 lbs of rotating mass, I'm not really sure what and where this is going to effect the FF car under braking, corning or accelerating a FF car but I believe the corning speed could be higher but slower coming out of the turns.

The tires are only (FF tires 22.5)(FC tires 22.0) so gear changing MAYBE? small ride height adjustment by .5" to get back to the setting you had with FF tires. The FC tires are .75" wider each tire but because were not going to have the side wall flex like with the FF tires, well it give more grip I will let you know after the 4. 1. 23 event because I have a FC coming to that event and we are going to mount his tires to my car for fitment, I'm hoping to drive on them with no setup changes for just the feeling the differences and can give you all some feed back.

Hello Jim, I hope this doesn't happen " But there are a sizable number of people with multiple new sets of Hoosiers. There'd be no way to get close to a well driven car with regular sized Hoosiers."

Ben

[ahowe]

Regarding what is being seen as the "easy button" for 2023... Things that I think are true:

• We're all running the same front tire. I see no reason to allow a 6" wide wheel. We've been running the FC tire on the FF wheel for ages. (Or at least I have.) The introduction of a wider rear wheel will only affect rear grip. My car is slightly rear grip limited... so I would see a little bit of a benefit from that. Not allowing a 6" wide front wheel would limit the benefit.
• An allowance for an 8" wide wheel should be accompanied by a restriction on tire size to prohibit the 22.0x9.0x13 tire. If we're responding to a force majeure situation, the change should be the minimum required to level the playing field.
• A setup change is required to maximize the benefit of the wider wheels and wider tires. Balance is shifted to the rear and the tire is shorter meaning gearing and ride height is changed.
• An allowance for wider wheels will result in wider wheels seen as a requirement if you want to be on the fastest equipment at Solo Nationals. (Your mileage may vary on actual speed.)
• An allowance for wider wheels for 2023 will not be well received if that rule change is not permanent. How many of us are going to buy a set of wheels (or even a pair of 8" wide wheels) for (effectively) one event?
• Those of us who have tires are even less likely to go out and buy a pair of wheels (likely $500 used and $1000 new) and pair of rear tires (at over $800 for the pair). It could happen, but speaking for myself... I won't.
• The difference between the 8" rear wheels and FC rear tires and the R25 rear tires on the 5.5" wide wheel is probably smaller than we all make it out to be. Even less so if the allowance is made late (and it seems like we're in that boat). I expect it will be less than 0.5 seconds per day.

The temptation would be to equalize things by an associated minimum weight change. Run the 8" wheel and run at 1130 pounds... or something like that.

On the other hand... running the R60 tire is the other easy button. Here's what I think is likely true about that:

• This is the "no cost" option. These tires should cost the same as the R25.
• Folks north of the Mason Dixon will struggle to get meaningful seat time on the tire before Nationals.
• Single driver cars could struggle mightily to be competitive with the approximately 30 minutes between runs at Solo Nationals.
• Setup changes are pretty minimal. Probably a bar adjustment to soften bars just a smidge. Maybe dial out some camber.
• This is likely slower than the R25 tire, depending on weather by potentially a non-trivial margin.

I don't see how this is a fair fight if it is cold. We should run Heat 4 or Heat 5 to help minimize the impact of the harder tire.

If you pressed me for an 8" wheel rule package, here's what I'd pitch:

An option to run up to an 8" rear wheel in combination with the Hoosier 22.0x8.0x13 tire and a 1130 pound minimum weight as an alternative to the current specifications.

All of that said, I don't like the 8" wheel option for this reason: I don't think very many people would exercise that option unless there was a guarantee that the 8" wide wheel is legal in 2024 and beyond. The short term answer becomes the long term answer by default... not because it is the right answer for 2024 and beyond but because it was the convenient answer on April 1, 2023.

My preference would be to do nothing for 2023 and focus our efforts on getting the right package figured out for 2024.

I would also participate in a gentlemen's agreement to not run the R25 tire in CM at the 2023 Solo Nationals if that is decided to be best for overall participation. (Understand that this may mean that I run my car on that tire in BM.)

My two bits (you know... inflation and all)

Andy

[Lynn]

[QUOTE]All of that said, I don't like the 8" wheel option for this reason: I don't think very many people would exercise that option unless there was a guarantee that the 8" wide wheel is legal in 2024 and beyond. /QUOTE]

I have three sets of used Hoosiers of dubious provenance. Those are what we'll use this season.

[Jim Garry]

I have three sets of used Hoosiers of dubious provenance. Those are what we'll use this season.

Hi Lynn,

Understood.

We all agree that everyone is different. In my case I just don't have much fun driving on old Hoosiers. The low grip and understeer with oversteer handling is exasperating. And at a big event I'd lose by 3 seconds more than normal. To me (not to everyone) I'd probably drive my Civic because it will behave better and give me a better chance of a reasonable finish.

Just my $0.02.

[Jim Garry]

Regarding what is being seen as the "easy button" for 2023... Things that I think are true:

....

Andy

All good points Andy. I can only disagree with one thing. I don't believe that the 8" wheels require 30 lbs of ballast. Other than that, I agree with everything.

[Jim Garry]

Ben Martinez has purchased a set of Hoosier 22 x 8 -13 tires and will be testing them on 5.5" wheels in two weeks.

[ewcmr2]

Ben!!! We need an update.

[ewcmr2]

Ben messaged me an update, there are pictures showing some tread graining.

Hey Eric I see on Apexspeed you want an update.


Could you put Apex this:
The FC tire do fit but with some small adjustments to my car the FC R20 tires are a sec slower then the R60 on a 65° day. The wear was really bad but this was at 16lbs of pressure.


Trying FC rims this weekend with the FC tire to see if the time comes back.

[CM/FFdriver]

Ben messaged me an update, there are pictures showing some tread graining.

Hey Eric I see on Apexspeed you want an update.


Could you put Apex this:
The FC tire do fit but with some small adjustments to my car the FC R20 tires are a sec slower then the R60 on a 65° day. The wear was really bad but this was at 16lbs of pressure.


Trying FC rims this weekend with the FC tire to see if the time comes back.

Jim Garry text me and asked me about what I found driving on the FC tire on our 5.5 rims to you all.

The tire didn't look too bad and the side walls were not to soft that I thought they could be, that said I had a little optimism because they were R20 compound and was thinking this could be good. Well that didn't work, the tire was fun to drive but as I put 3 laps on the tire it started to chunk/feather to the point that I stopped and put on the R60 from a 65 degree day. I went out on cold R60 tires and was faster on my first run, I didn't expect that but did one more run on the R60's and made up another .400 which made the R60 1.000 sec fast then the FC R20 tire on our 5.5 rims. The tires were check for tire temp and were 95 degrees before my last run, so right there I called it I will be running the R60 tire at the National's.

Ben

[griceiv]

Jim Garry text me and asked me about what I found driving on the FC tire on our 5.5 rims to you all.

The tire didn't look too bad and the side walls were not to soft that I thought they could be, that said I had a little optimism because they were R20 compound and was thinking this could be good. Well that didn't work, the tire was fun to drive but as I put 3 laps on the tire it started to chunk/feather to the point that I stopped and put on the R60 from a 65 degree day. I went out on cold R60 tires and was faster on my first run, I didn't expect that but did one more run on the R60's and made up another .400 which made the R60 1.000 sec fast then the FC R20 tire on our 5.5 rims. The tires were check for tire temp and were 95 degrees before my last run, so right there I called it I will be running the R60 tire at the National's.

Ben

Ben,
Any additional comments about the experience at the crows tour? Looked like some interesting testing going on.

[Ocho]

Looking for feedback for rules change moving forward -

If you're not on Facebook - the MAC is looking for CM input on the prefered direction moving forward. As we all know, R&S brokered a deal to get one more run of the old rear tires made. Hoosier isn't going to make more, that was the last run.


So we have a poll on Facebook looking at the following 3 options. If you have Facebook - please place any responses on that post in the SCCA Modified group.

the 3 options are:
1) no changes - use what tires you can find
2) allow 6"&8" wheels (and continuing to allow existing wheels)
3) Moving to a spec tire like what's used in the UK or Australia (like a Toyo 888r)


thanks!
Brad Smith - Chair, MAC

[Lynn]

I'm not on facebook.

My preference is 2.

[CM/FFdriver]

Ben,
Any additional comments about the experience at the crows tour? Looked like some interesting testing going on.

Hello,

Yes, I was just testing again because now it was in the 80 degrees weather and I put the FC tire on the FC rims and they were not that much faster than the R60 that I put on for day 2. I was expecting to be in the top 3 in pax, was top 10, after driving on this setup for the last 2 events I'm not feeling like there not any faster than the cantilever tire (from the old r20 front & r25 rear setup). Buying a new set of FC tires in July to test between the R20 cantilever tire and see how much difference there is. I'm sure with some small changes the FC setup they will become faster but that could be next year if the rule goes through, just not putting in a lot of time on setup.

Ben

[Unbalanced Engineering]

Hey Ben, thanks a ton for doing the testing. I'm surprised that the R20 FC rear on the 8" isn't faster than the R60 cantilever. Very interesting.

Also not on FB.

I would suggest that if #2 is the consensus, we go with 5.5" front wheel and 8" rear so we can at least use the wheels we have and only have to buy rears. Just a thought. I think most of us are running the FC size front on the 5.5 now.

Thanks,
Jason

[lowside67]

Hey Ben, thanks a ton for doing the testing. I'm surprised that the R20 FC rear on the 8" isn't faster than the R60 cantilever. Very interesting.

Also not on FB.

I would suggest that if #2 is the consensus, we go with 5.5" front wheel and 8" rear so we can at least use the wheels we have and only have to buy rears. Just a thought. I think most of us are running the FC size front on the 5.5 now.

Thanks,
Jason

No real dog in the fight, but I think it makes sense to allow 6" fronts if 8" rears will be allowed.

It allows you to sell a complete set of 5.5" FF wheels and buy a complete set of 6/8" FC wheels, rather than having marooned half sets.

I am confident the difference between the 5.5" and 6" front using the same FC front tire is nominal, so the extra choice of wheel size/style only serves to reduce potential costs and make it easier in some ways by just going to full FC wheels/tires.

It also really doesnt surprise me all that much that the 8" rear is not meaningfully faster as there's just not that many scenarios (especially at the courses Ben runs) where the car is traction limited anyways on the smaller wheels, and there is a weight penalty to the larger wheel/tire.

-Mark

[-pru-]

For those not on FB, my feedback on the poll...

I was an early proponent of allowing FC 6”and 8” wheels; it would allow the class to continue to run soft/qualifying compounds offered by Hoosier, Avon, etc.

After reading numerous comments for/against FC wheels, I’ve changed my stance; no new wheels. That is, I don’t see the need to go down the SoloVee path with the FF as there are plenty harder/non-qualifying tire options available. I will miss the grip level but it is time to move forward (and thank you Hoosier / R&S for giving us 1 more year!).

With all the stated, I do want the SCCA/SEB/MAC deciding on a tire (spec tire) UNTIL we have a few years of run time on the available options. Given Ben’s feedback, I think the Hoosier CF R60 is best choice as well as being an “easy” solution; that is, very little (if any) set up changes needed outside of needing a co-driver…hence my vote of “No changes”

[TedV]

in conversations elsewhere, I realized folks might know that various chassis of FF were not designed around the FC sized rims. Would the earlier chassis FF be at a disadvantage for not being able to fit the wider rim without making a change to the track on that end? The rim would need to move 1.25" in at the lip to keep from impacting the handling and setup. Everyone can easily throw a tape measure at the 5.5" rim and see if suspension would interfere. CFF bias R60 is R7 compound. Radial FF is A7 compound. Avon is... oh wait, Goodyear is dissolving Avon, never mind.. Anyone with SoloVee's or Gen3 SpecwReckerFords gonna send in letters?

Elsewhere, I mentioned.. keep the 5.5 spec for front on FF cars and only allow changes to the rear for an 8" wide rim to fit the 22x8 tire. Why make folks buy 4 new rims when they could make it work with just buying 2 rear rims?

[R. Pare]

Running the FC front tire on a 5.5" rim will most likely necessitate upping the front spring rate to keep the rate at the contact patch the same - mounting on the narrower rim will decrease the tire spring rate quite a bit. We experimented with that on a front-runners FF a couple decades ago, and if I remember correctly, we had to increase the front springs something like 200 pounds.

[Unbalanced Engineering]

Like I said earlier, I believe many (most?) of us are already on the FC front... I have been for years at any rate.

Jason

Running the FC front tire on a 5.5" rim will most likely necessitate upping the front spring rate to keep the rate at the contact patch the same - mounting on the narrower rim will decrease the tire spring rate quite a bit. We experimented with that on a front-runners FF a couple decades ago, and if I remember correctly, we had to increase the front springs something like 200 pounds.

[TedV]

Running the FC front tire on a 5.5" rim will most likely necessitate upping the front spring rate to keep the rate at the contact patch the same.

Also wouldn't we read that as since most everyone is already running the 20.5x7-13 on the 5.5 rims, once they spend the cash to get the 6" rims they then will have to spend more to make the front work best?

[lowside67]

Also wouldn't we read that as since most everyone is already running the 20.5x7-13 on the 5.5 rims, once they spend the cash to get the 6" rims they then will have to spend more to make the front work best?

Taking the same tire you are already running, and moving from a 5.5 to 6.0" rim is not going to require a 200lb-in spring change, sorry, there's no way that's correct. I would venture a guess that in a double blind test, most of us would not be able to tell the difference. I think the 6.0" would be better for tire wear as it'll support the tire better, but there is no way this is a huge game changer performance wise.

I know I dont have a FF but I am participating in this thread because I truly enjoyed it when Phil and I were driving ours and I would hate to see the class go away. I think it is being "penny wise and pound foolish" to worry about the price of a spring or wheel swap versus the decrease in value of the cars no longer being competitive and being homeless which most would be if not a top vintage choice or a modern car.

-Mark

[chrisw52]

I can't believe no one has considered allowing 5.5-6" rims on the front... then what debate is left?

for clarification: allow 5.5" FF rims AND 6" FC rims along with the 8" rears.

[Unbalanced Engineering]

Pretty sure if you allow the 6" front, we'll all need to switch to it...

[B17overhead]

Taking the same tire you are already running, and moving from a 5.5 to 6.0" rim is not going to require a 200lb-in spring change, sorry, there's no way that's correct. I would venture a guess that in a double blind test, most of us would not be able to tell the difference. I think the 6.0" would be better for tire wear as it'll support the tire better, but there is no way this is a huge game changer performance wise.

I know I dont have a FF but I am participating in this thread because I truly enjoyed it when Phil and I were driving ours and I would hate to see the class go away. I think it is being "penny wise and pound foolish" to worry about the price of a spring or wheel swap versus the decrease in value of the cars no longer being competitive and being homeless which most would be if not a top vintage choice or a modern car.

-Mark

I'm in total agreement with Mark's assessment. Also, any small changes in track like 1/2" or even 1" will be "in the noise" as well. There are also wide track kits that some in CM solo have applied to their FF that are much larger than that in track change, so what's the issue?

[TedV]

any small changes in track like 1/2" or even 1" will be "in the noise"

Not sure if you are trolling or if you honestly believe this as I was once told by someone having tire wear issues "making changes to a car setup to suit a tire is the most ridiculous thing I have ever heard!!!" ???

:: edited to reduce the amount of question marks ::

[B17overhead]

I'm in total agreement with Mark's assessment. Also, any small changes in track like 1/2" or even 1" will be "in the noise" as well. There are also wide track kits that some in CM solo have applied to their FF that are much larger than that in track change, so what's the issue?

To attach real numbers to wide track kits that I referred to in earlier post: in the case of the Swift DB-1, the "wide track" modification kit increased track in the front (and thus the overall width) by 3" out to 72" overall. Nationals were won by both narrow and wide track DB-1's, but a scan of the many posts on this topic indicate that all of those who went with the kit liked it. In spite of the DB-1 being an old school rocker arm car and thus the worst possible case of all as probably more susceptible to rocker bending stress than a pull or push rod car, in reality, I could not find anyone reporting problems with undamped movement nor bending.

So, what does it mean to you in solo CM with your tire supply dilemma?

Well, just that there should not be any meaningful mechanical issues to consider from changing your track a smaller amount than the wide track kits did. Don't throw out the 6+8 rim option for THAT for as a legitimate reason.

You may indeed have other reasons to pick a different option, but that shouldn't be one.

I would also point to all the same mfg. FF1600 chassis over the years that were ALSO available as FF2000 using the 6" and 8" rims instead of the 5.5's.

In view of Ben's successful testing at Crow's with R60 rears, you should definitely pay attention to that- but at the same time, look at the larger picture. Crows is fairy grippy old concrete and the courses are usually long AND usually with sustained higher speed sweepers or offsets too. So, even on a cool 65 F day, tires are likely going to heat up more than 65 F in New England on a shorter course on lower grip asphalt. Then, there are days in New England that are even colder at 45-50 F. We see those low temps in AZ too since we run all winter here.

In the end, when YOU in CM go to decide what you want in the long run for 2024 and beyond, I just suggest that you consider if you are going to be happy with just one hard tire compound from just one Mfg. for all seasons and all pavements? There are sure to be some of you who will never ever run on pavement as good as even medium grip pavement.

[CM/FFdriver]

Also wouldn't we read that as since most everyone is already running the 20.5x7-13 on the 5.5 rims, once they spend the cash to get the 6" rims they then will have to spend more to make the front work best?

Ted, At this point of just driving on the 6" rim and then going back to the 5.5" rim with the same FC tire has not made me change my springs rates by 200lbs? that said I've only driven on for the last 4 events a total of 20 laps and I believe I'm under driving the FC tires but if the rule change happen I will be on full test mode.

[CM/FFdriver]

In the end, when YOU in CM go to decide what you want in the long run for 2024 and beyond, I just suggest that you consider if you are going to be happy with just one hard tire compound from just one Mfg. for all seasons and all pavements? There are sure to be some of you who will never ever run on pavement as good as even medium grip pavement.

B17,

Here, Here

Ben

[Unbalanced Engineering]

I was NEVER referring to the track change, but was referring to the tire shape / pressure / contact patch etc. Do I believe this necessitates a significant spring rate change? No. Do I think it will make a difference in front grip? Yes..... Just my .02

[B17overhead]

I was NEVER referring to the track change, but was referring to the tire shape / pressure / contact patch etc. Do I believe this necessitates a significant spring rate change? No. Do I think it will make a difference in front grip? Yes..... Just my .02

I sure wasn't taking issue with anything you said, Unbalanced! There was one post picking on ME about my mentioning small 1/2" to 1" track changes (from 6 and 8 inch rims). I was just saying that any small track change from running 6+8's would be relatively inconsequential. There was a history of no ill effects from larger 3" track changes from the old wide track kits for FF1600 as well as the FF1600 chassis that were also sold as FF2000's.

[Unbalanced Engineering]

Ah, totally understand. Just wanted to make sure I was clear with what I was saying about the 5.5 vs 6.

Thanks B17.

Jason