Just Your Opinion about Tires

[CM/FFdriver]

Hello All,

I was working on my CMod car for the next season and thought I would watch the FC race on TV when the commentator said "these FC with their skinny tires" What? so I watched and then decided to looked up the rim and tire size for the FC.

So this is what I found for the FF/CM cars that we run, The 43130 would be the traditional FF front tire size but we all use 46164 which is a FC front tire so were all half way there just not the rim size.

Now if we go to the rear the 43309 is what I use and the 43286 would be the FC rear tire, so I said Hmmm.. what do my measured contact patch look like, interesting 8 inches that hits the ground ok not sure what the is the real contact patch for the FC rear tire but because their not using a cantilever rear tire it could be very close to what Hoosier advertises at 8.5 inches.

So that is a .5 inch wider rear tire if we were to use the FC rear tires. I know the expense of buying new rims for some could be on the wrong side of being more expensive but FF rims are still very popular so it's not like you couldn't sell them. If Hoosier made up their mind one day and Bails on building the cantilever rear tire, thats not to say they wouldn't make the rear cantilever tires just for the autocross people but just thinking of a possible future.

For me Going to the radial tire even if the would make them in a autocross compound is not going to work for me.

So there's the question, What Do You All Think?

Ben

[Barry Ott]

Hey Ben!
I talked to Jeff Spear a couple years ago about "our" tires going away:

https://www.apexspeed.com/forums/sho...F-cars-in-2016

In summary, I think we're ok, but you never know.

As far as running the FC rear tires, David Flesher ran them on his car at Nationals last year ('18) and commented that he lost about one inch of contact patch on our 5.5" wheels and they didn't work particularly well (I'm paraphrasing, sorry if I didn't get that exactly right). With that in mind, and if Hoosier stops making the cantilevers for us, we'll have to consider how to move forward. Changing to an 8" wheel is a reasonable option, or maybe we could find another Hoosier tire, or another manufacturer or ???? At the risk of being reactive instead of proactive, I think it's hard to decide what the right path forward would be without knowing the real situation.

Respectfully,
Barry Ott

[TeamFRD]

... David Flesher ran them on his car at Nationals last year ('18) and commented that he lost about one inch of contact patch...

1 inch on each side! Fail. I could not hear it on the video but I feel all I did was spin them - slightly. Plus the acceleration to the finish lines was less - when comparing my RPM/speed to other's video and data. These were also a pain to have mounted.

With that said, several times I've almost thrown in the towel when trying to have the rears mounted locally. Plus, going up and over 80 PSI gets everyone puckering!!! A race tire dealer charged me almost 100 for 2 rears. [ My old Revolutions and Compomotives do have the bead bump which, I believe, is not helping.]

I'm on board for going to 8" rears. Hell, keep the 5.5. fronts. Instant spares.

Another point is the used R25 tire market is significantly reduced now.

David

[pleavens]

For pure performance, I would love to have the FC wheels all around. I see a potential balance issue if using the rear only (at least with newer cars) This would allow more tire options with my RF98.

The current situation, being at Hoosier/Continentals mercy is very frustrating. The tires are relatively expensive, slow to heat, unable to "turn on" in other then ideal conditions, and I've had issues with the age of several I've purchased.

Frankly, the only thing that makes me buy the Hoosiers (5 sets last year) is that "everyone is running them" and the contingency program which is nice but limited.

Phil

[TedV]

I spoke with Jeff Speer at Nationals and yesterday.

The current FF R25 slicks are selling good enough that production isn’t going to be dropped any time soon. The 43130 20x6-13 is the Club Ford size in hard R60 compound. FF hasn’t used 6” fronts road racing in years. The road race FF, FC and FSAE all use the 46163 20.5x7.0-13 R25(insert letter of the latest compound) and it definitely will not be going away. 43309 22.5x7.2-13 cantilever is still selling well enough it isn’t expected to go away. They have experimented with softer compounds, but they just didn’t work out well. Avon lists a softer compound in some of their tires, but if you think Hoosiers are expensive, check their pricing and availability. I was working a tire test many years ago when Avon was one of the possible choices. Their tires were stuck in customs and they missed the testing days completely. They were not chosen as a spec tire supplier for some reason. Hmmm.. not sure why.

Rain tires. Only size available they are making is the radial wet if you want new tires. The construction is not as stiff as the dry radial and should work fine. Side note, before radial wets were available, road racers and autocrossers used the bias ply Dirt Stockers even when they had the car set up for radial tires. No, the camber might not be correct, but the soft compound and water shedding is more important. The compound will survive drying conditions road racing, so should not be a problem autocrossing.

Fronts on the rear: You need to change A LOT more than just the tires to make it work. Road racers did it on long tracks primarily for less drag and higher top speeds. There is only .75” difference in tread width between the front and the rear, but 1.8” in tire height. Drops the car .9” and will completely change your geometry. You will need to re-engineer the rear of the car. They had faster tire wear as a result of less rubber around the circumference and rotated the tires around between sessions if they didn’t destroy them in one session. The FF rears have gotten narrower over the years and is in the 7.25” range.

FC,FB, FM,Sports Racer sizes: use the same fronts or the 43168 20.0x7.5-13. Don’t have a dyslexic moment when ordering tires or you will get the wrong ones. It has happened. Rears are the 22x8 or 22x9. They are a bit shorter and of course wider. As of now, there is no spec tire on the horizon for the classes like FC so those tires should be available. There comes a point when there are minimum quantities needed to be produced and they need to sell before aging out in a warehouse (Jeff didn’t exactly say that but I understand economics) If the soft compound FF tires do go out of production, a rule change could be requested to the SEB for allowing wider rims to run the FC size. Problem being, some cars suspension pick up points are where the wider rims will want to be to maintain the same tire placement for geometry. Some cars needed to make new lower arms to get the Spec Radial Dry tires in their happy place. Unless the tire is made cantilever, the sidewalls prefer to be on a rim width within .5" of the tire tread width.

Most cars running slicks have needed a codriver to keep heat in the tires between runs better than a single driver for as long as I can remember. By the way, I make a great tire warmer!