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12th Scale Tires Made Simple (Sort-of)

Posted by Cristian Tabush on 7/5/2015 to Tech Articles
12th Scale Tires Made Simple (Sort-of)
Let me start this article off by saying that this information is entirely speculative. The information might not be 100% accurate as we can only share what we have been able to compile over the past couple of years, through trial and error and discussions with fellow racers and manufacturers. However, the information that we have gathered will make you, the fellow racer understand foam tires a bit more and hopefully you won't feel as lost as you take the dive into foam tire racing.

You ready? I'll try to make this as simple as is possible.

Tire Brands:

There are many tire brands out there, and knowing which ones are similar/ the same is important.

-BSR, CRC, Pro One and Jaco are all mounted by BSR. These tires are almost all the same. There are a couple of things that each brand might specify that makes them different, but for the most part they are the same. One thing of note that is important is the nomenclature of the BSR vs Jaco and CRC is a little different, but we will expand on that later.

All the BSR based tires have 3 families they essentially use, we will identify them as synthetic foam, natural rubber and blend.

  1. The synthetic tires are the old school, light weight, easy to true "dry feeling" tires, These include tires like CRC/Jaco Yellow (BSR White), Black, Gray, etc. These tires offer the highest wear rate and lowest grip. Many racers still use these under high bite conditions.
  2. Next we have our natural rubber, this includes pink, magenta, double pink, team purple (lilac in all other brands but bsr) purple and other tires. These tires provide a ton of grip, but they tend to get sticky in high bite conditions. This rubber will not wear as easily and the cars will pick up gunk and fibers from the carpet under most high bite conditions. This is especially bad if the humidity is high. Natural rubber tires are usually the best alternative for low bite and asphalt.
  3. Lastly, we have what I like to call blends. These are the new tires most people are running today. These initially were called "JFT foam" by some as it was believed that the tires were the same as the JFT branded tires. I like to divide the blends into two further groups, high rubber and low rubber content. The high rubber would be the new rear Orange and Red available from BSR and the low rubber would be Green and Blue Varieties. When I asked John Foister at BSR Tires about the difference, he said they came from the same "family" of foam, but they offered different grip. According to John, the Green/Blue has more bite than Orange/Red, but in my testing as well as others at our track, Oranges (being equivalent to in hardness) offer more bite than Green when the grip is high and absolutely no grip when it is lower. The Orange foam has a denser pore structure and the tire is not as prone to chunking. Important to note is that BSR blue rears are not the same as the BSR Blue fronts.


-JFT: JFT stands for Japan Foam Tire. They started the new wave of foam tires we are all using now (Blue/Blu, Green/Greene, Dbl Blue, etc). Their tires are not quite the same foam as the BSR based tires, but work in very similar conditions.

  1. JFT offers two varieties A Type (for asphalt) and C Type (for carpet). This does not necessarily mean that the other types will not work on other surfaces, but this is what they recommend. Their A Type tires are what I would consider close to the natural rubber variety and are named consistently with other natural rubber tires. They offer pink and magenta only.
  2. Their C Type tires are offered in Yellow/Green and Light Blue for the rear and Green/ Light Blue and Dark Blue for the front. JFT uses the same foam for fronts and rears if the color is the same. Set-up wise, they seem to generate more bite than BSR Tires, so the car tends to be a little more aggressive with them.Their green rears look very similar to the BSR Oranges, but the grip is more in tune with their Greens. They have a denser pore structure and are fairly resistant to chunking.


-Ulti: Ulti is another Japanese brand that offers a vast array of compounds. Ulti tires has their own way to rate their tires and it is really hard to equate them to other brands. This is what I can tell you, they have 4 different varieties in different hardness.

  1. J Compound is a high rubber content tire, similar to Pink/ Magenta. Soft would be close to a pink. These offer the most bite and are great for asphalt and as a carpet front tire. (J hard being very popular)
  2. X Compound is a "balanced" blend, similar to JFT Blue/ Green. Soft is equivalent to Green, medium to Blue in hardness. Great for carpet/
  3. Y compound is a high synthetic blend with lower grip. This is not a very popular variety.
  4. Z Compound is a very expensive "special" foam that is supposed to be magic on asphalt. They only make it in soft shore.
-The European tires: There is a bunch of great European foam tire brands in the market which use their own types of foam as well as traditional foams available out there. Unfortunately we don't have too much, or easy access to them in order to test them.

Tire Chart (coming soon)

Below is a simple chart that tries to explain the family, the shore and the similarities across brands.


Tire Tips:

  • Truing Tires:

Many people stay away from foam racing because of the dreaded "T" word. Let me tell you first and foremost, it really is not that bad. You really don't need to cut your tires that often, and unless you are at huge national event, you really don't need to true them but the first time. Especially if you rotate tires Left to right after every run.


-Tire Diameter:

Not cutting your tires down the right amount can make your foam racing experience extremely frustrating. You want a balance of wear and performance, so it is important to pay attention to this.

If you are racing on carpet, you have to evaluate how much grip your track has. If your track is low to medium grip, you can get away with bigger tires, if you are on higher bite, you have to cut them smaller, there is simply no way around it if you want to go fast. Remember that on high bite, you have less wheel spin, so even though you cut your tires down a little more, typically the wear rate is lower on higher bite tracks.

On asphalt, bigger tires are needed, especially at the rear. Bigger tires provide more lateral bite, which is what you want.

So you are probably asking, where should I start? We suggest the following:

Carpet tire size (in mm)

Low to Medium Bite:
Rear:42.5-43.00
Front: 42.0-42.2

Medium To High bite
Rear: 41.5-42.0
Front: 40.5-41.0

Big Race:
Rear: 40.5-41.0
Front: 39.5-40.0

Asphalt Tire Size (in mm)

Parking Lot
Rear: 44.0-45.0
Front: 43.0-44.0

Prepped High Bite
Rear: 43.0-44.0
Front: 42.0-43.


  • Truing Technique

Truing is a simple task if you have the right tools. Using a truer is a simple task, but the finishing technique is important. Usually you have to pay close attention to the edge of the tires. The more rounded the side of the tire, the more side bite it will create at that end. A more rounded edge will also prevent chunking of the tire.

  • Tire Treatment

Most facilities have moved towards odorless traction additives. Some of these additives do not evaporate very quickly and some do. This seems to be something that is also dependent on tire compound and ambient temperature. Green compound for example seems like it never dries, especially when it is colder. We have found that wiping the tires off 15 minutes before we go run allows the sauce to cure which in turn makes the car come in much quicker with Green rears. Blue compound on the other hand, do fine when wiped off right before hitting the track.

  • Tire Fuzzing

Sometimes, in conditions of increasing grip, foam tires will get sticky and pick up fuzz and debris from the track. This is highly dependent on the rubber sedan tire that is being run at your local track and the compound/ type of foam you are running on you car. The softer the sedan tire being run as well as harder/ higher rubber content in your foam tire, the more trouble with fuzzing that seems to occur.

There are ways to get around fuzzing under most conditions, and it usually just involves the selection of the correct foam compound. Basically, the more fuzz you get the softer the tire and the lower the rubber content you want to run.

For example:
  1. Problem: Car fuzzes with Team Purple fronts and car starts pushing Solution: Use a softer front tire and or different family of foam. Replace it with Blue or double blue front.
  2. Problem: Car loses rear bite 6 minutes into the run. Blue rear tires look almost clean but have small carpet hairs. Solution: Use Green rear tires. The softer compound wears instead of getting sticky, minimizing fuzz.


Tire Selection

Now, with all the information above, it's time to make a decision on which tires to run. If it was me giving you the advice, (and you listening), I would start with 2 front compounds and 2 rears. In today's carpet world, Green Rears (whether JFT or BSR derivative) and (light) Blue Rears should have you covered 99% of the time and for the front, blue (light blue JFT) and double blue (dark blue JFT) should do the trick.

I know you may wonder about other compounds out there and if they might be better, trust me, they probably won't be. Even if there are other tires that can be as fast, the synthetic family wears out really fast and the high natural rubber will probably fuzz on you over an 8 minute run. The Blue/Green "blend" family seems to be the most versatile foam type available today, they last a good while and sticking to them will make your process of tire selection more simple as well.


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Date 12/6/2015
Tito bufford
Thank you for the info Christian. Good read.
Date 12/17/2015
Matthew
Thanks for the tips!
Date 12/28/2015
Jörn
Hi Cristian, thank you for your discribtion. You write JFT offers two varieties A Type (for asphalt) and C Type (for carpet). But what is JFT S Type?? Greetings Jörn

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