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This is a place to share knowledge related to 1/12th scale racing. It is not to be used for conversations.

Click links to go to manufacturer product page. If any are missing please add them!

Pre-mounted tires readily available in the US:
Gluing your own donuts:
https://www.youtube.com/watch?v=hm7z1rz-74s - Special thanks to Edward Pickering!
Truing tires:
https://www.youtube.com/watch?v=8wqHOLWq6Uc - Special thanks to Edward Pickering!

The following information came from HERE, with some editing and information added. Thanks Christian!


BSR, CRC, Jaco:
Pro One is no longer selling to the public, but it and the brands above are all mounted by BSR and use the same foam. The nomenclature of the BSR vs Jaco/CRC is a little different in a few instances but is otherwise the same. The BSR foam consists of three families, and can be identifed as synthetics, naturals, and blends.

Synthetics - 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 continue to use these nder high bite conditions.

Naturals - These tires are usually the best alternative for low bite and asphalt. They include Pink, Magenta, Double Pink, Lilac (BSR Team Purple), Purple, and other tires. These tires provide a ton of grip, but tend to get sticky in high bite conditions. This rubber does 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.

Blends - These are the tires most people run today. They were initially called "JFT foam" by some, as it was believed that the tires were the same as the JFT tires. We can divide the blends further into two groups: high rubber and low rubber content. The high rubber would be the new rear Orange and Red from the BSR family, and the low rubber would be the Green and Blue varieties. When, asked about the difference, John Foister from BSR Tires 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 from track testing Oranges offer more bite than Green (being equivalent to in hardness) 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. It is also important to note is that BSR Blue rears are not the same as the BSR Blue fronts!

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). These tires are a little different than the BSR tire family, but work in very similar conditions. They offers four varieties A (asphalt), C (carpet), S (???), and R (???). This does not mean that those types only work on that surface, but this is what they recommend.

JFT uses the same foam for fronts and rears if the color is the same.

A: Used on asphalt, considered close to the natural rubber variety and are named consistently with other natural tires.
C: Used on carpet, considered a blend.
S: Used on carpet?, tires are ???
R: Used on carpet?, tires are ???

For setup, the JFT foam seem to generate more bite than the BSR, therefore the car tends to be a little more aggressive.

Ulti is another Japanese brand that offers an array of compounds. They have their own way of rating tires, and are difficult to equate to other brands. They have 4 different varieties, each in varying degrees of hardness.

J: 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/carpet front tire. (J hard being very popular)
X: "Balanced" blend, similar to JFT Blue/ Green. Soft is equivalent to Green, medium to Blue in hardness. Great for carpet!
Y: High synthetic blend with lower grip, and is not a very popular variety.
Z: A very expensive "special" foam that is supposed to be magic on asphalt. Only make it in soft shore.
European tires:
There are many great European foam tire brands that use their own types of foam, as well as traditional foams. SOmeone with more knowledge about them will need to fill this in!

Tire Diameter:
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 run bigger tires. If you are on higher bite you have to cut them smaller, there is simply no way around it. Bigger tires are needed for asphalt, especially in the rear. The larger tires provide much needed lateral bite.

Carpet (mm)
Low - Medium Bite
Front: 42.0 - 42.5
Rear: 42.5 - 43.00
Medium - High Bite
Front: 40.5 - 41.0
Rear: 41.5 - 42.0
Big Race
Front: 39.5 - 40.0
Rear: 40.5 - 41.0
Asphalt (mm)
Parking Lot
Front: 43.0 - 44.0
Rear: 44.0 - 45.0
Prepped High Bite
Front: 42.0 - 43.0
Rear: 43.0 - 44.0

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

Saucing half front and full rear is a good initial starting point. If the front of the car is too agressive you can sauce les than half, or for a shorter amount of time.
Tire Fuzzing:
In conditions of increasing grip, foam tires will somewtimes 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 and the harder/higher rubber content in your foam tire, trouble with fuzzing seems more likely to occur.

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

Problem: Car fuzzes with Lilac/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.

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:
Starting out, pick 2 tire compounds for the front and rear. The following should have you covered 99% of the time.

Front - Green and Blue (BSR) or Green and Light Blue (JFT)
Rear - Blue and Double Blue (BSR) or Blue and Dark Blue (JFT)

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 blends family seems to be the most versatile foam type available today. They last awhile, and sticking to them will make your process of tire selection simpler.
Tire Chart:

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Old 06-14-2008, 02:13 PM   #28861
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Default help please 1/12th

just bought 2 RC12L3 associated pan cars and wondered what gears people run on i have 48dp pinions but wondered what spur to run with.

also as you guys in usa get parts cheaper than us in uk can you recommnebd any on line shops in usa with parts for associated that post to uk cheaply.

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Old 06-14-2008, 08:26 PM   #28862
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I got a 12L4 want to run it just to play,lowest turn motor i can get is 12 turn,what pinion should i use?Epic, Checkpoint whats a fast motor.It should fly with a 12 turn right?How do you change front ride height?I got a novak gts pro ,does running 4 cells change the motor i run,like can i run less than 12 turn w 4 cells???Thanks in advance.
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Old 06-16-2008, 12:22 PM   #28863
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12R5 with BL 4.5T
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Old 06-16-2008, 12:28 PM   #28864
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Hi guys, I have been working on the setup of my 12th car that I have been developing and need some advice. I personally like LOADS of steering, handling wise but with this car, having so much steering is making the rear end really loose after 6 minutes. It's a nighmare handling wise after that point. We are only allowed to use Corally Silver fronts and Gold rears, tyre wise as these don't leave too much mess on the carpet in the (church) hall we race in. I use .20 front springs, 3 degree castor, 1.5 degree camber. Thick grease in the damper tubes, Hara medium centre spring with 40 weight oil inside, 3.5mm ride height all round, Audi R10 b'shell. I also use a carbon t-peice (hence the thicker oil in the centre shock and damper tubes). I want to try and keep as much steering as possible, but not so much that I loose the rear end! Any advice would be great!! Cheers, Chris.
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Old 06-16-2008, 12:37 PM   #28865
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Chris, start by dumping the Audi shell. It has lots and lots of front end, but it also lets go of the rear suddenly at low speed. I reckon you are overworking the rears, which run out of additive, and that they are Golds isn't helping that.

Switch to a Zytek, or, if you aren't worried about running at BRCA Nationals, a Parma Speed 8 HD. The Zytek is smoother all round. The Speed 8 HD has more front end, but doesn't let go of the rear as the speed drops.

If that doesn't do the job, junk the carbon T-piece. Carbon winds up too much, has little damping from its resin, so the car loads up but, as the speed drops and the weight transfer starts to unwind, the carbon T-piece will 'snap' back.

One thing is certain - if you're running a T-bar car, the closer it is to a 12L4 the better it will be. After all these years, the T-bar car is still the most user-friendly, and the best combination of parts and settings is in a kit 12L4. Get closer to that and you'll get closer to your ideal. HTH
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Old 06-16-2008, 03:44 PM   #28866
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wingman2 - i would try the following (you might also wanna raise your ride height to 4mm to allow the car to roll more).
1 - running a lighter shock oil, a softer spring and more pod droop. 40lb sounds really hard for a t-bar car. i run that in link cars on high grip carpet.
2 - thin out the damper tube lube
3 - move to .022 front springs.
4 - different, thinner tbar
5 - increase the front width by adding a few shims on the axles
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Old 06-17-2008, 11:13 AM   #28867
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Hello all. I just bought a slightly used T-Fource. All seems to be good on the car except for one thing...the little ball cups on the side dampers don't want to stay in place. (Actually, one does and one doesn't.) What can I use as a replacement for these?


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Old 06-17-2008, 11:26 AM   #28868
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DuBro #181 2-56 ball links should be a direct replacement.
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Old 06-17-2008, 11:28 AM   #28869
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I will give those a shot. Thanks, Trips!
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Old 06-18-2008, 01:29 AM   #28870
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Thanks for the reply guys. Our club (Plymouth) runs in a smallish church hall and many t-peices get broken either hitting the outside wall or when another car hits you whilst racing really close together. Thats why I am going with the carbon t-peice for now. I have noticed that you have to up the damping on both the centre shock (hence 40 wt oil) and the damper tubes (really thick Corally diff grease) so that it does not 'snap' back to the normal position. The car itself runs brilliantly, just not for the whole 8 minutes! And yeah, I agree that the rears are getting overworked. I have mounted the servo flat on the chassis instead of at an angle, that should take some initial steering away. I am also spraying a HB b'shell at the moment to try as well. (I ran the Audi as the FX speedo I use needs quite a bit of space under the b'shell). Away, thanks again and I'll let you know how it goes! Cheers, Chris.
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Old 06-18-2008, 08:16 AM   #28871
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Originally Posted by SlowerOne View Post
start by dumping the Audi shell. It has lots and lots of front end, but it also lets go of the rear suddenly at low speed.
I'm going to find out @ the SummerShoot Out this weekend if this is the case as I have 2 of them, but will be on the BMI DB12R
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Old 06-18-2008, 11:45 AM   #28872
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I think it is the case that the Audi shell has loads of front end as I have been told by quite a few people to add a gurney flap to the rear to balance it out.
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Old 06-18-2008, 11:58 AM   #28873
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Chris, that helps, but in reality all it's really doing is masking the basic characteristic of the shell. If you're running a small track with low speed squirts between hairpins, I can see why it would work well. But on a National track with high corner-approach speeds, and tricky corners at medium speed, the Zytek and HB Raynard are the ones to use. HTH

I understand what you are saying about the carbon t-bar, so you've put yourself in the position of having the rear so stiff it is overworking the tyres, and the grip goes. You can fiddle with it all you like, but a 12L t-bar, 30wt oil, green (olive) spring and 5000wt side damping is the cure you need.

Get a BMI DB12R - nothing to break! If I can't break it...
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Old 06-18-2008, 11:42 PM   #28874
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Thanks for the help. I have a regular AE t-peice, what I will do is stick that on my car and see what differance it does. You are correct though, the rear is quite stiff which in turn does overwork the rear tyres. My car does have the damper tubes set really low though, and because of this there is not that much movement within them. I have to use thicker than normal grease in there to get the same 'feel' over damper tubes that are mounted higher up and using thinner oil.(I hope that makes sense!)
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Old 06-19-2008, 04:59 PM   #28875
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hey guys i have a 12th race next weekend onn carpet with a 60 or so foot straightaway. What is the recomended gearing for a 10.5 brushless? and what is the recomended spur gear size??
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