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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:
Pre-mounted tires readily available in the Europe:
  • Hot Race ??

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 Charts:



JFT (Japan Foam Tire)


Enneti (Xceed)

As of now, ROAR is staying 1S (3.7V nominal; 4.2V fully charged) for 1/12. There are many 1S ESC's with a built in BEC so nothing else is required to power the receiver and servo.

If you don't want to lock yourself into a 1S specific ESC, you do have other options! It is possible to use your 2S ESC without a booster or receiver pack, and the ESC simply supplies the lower voltage. If that does not appeal to you, you will need to use an Rx pack or booster. The Rx pack and booster will both supply the receiver with a higher voltage than the 1S pack.


If you choose to use a voltage booster, it works exactly how it sounds. Instead of plugging the ESC into the receiver, it plugs into the booster, and the booster plug goes to the ESC, supplying the higher voltage.

If there are any missing please add them!!

If anyone would like a need for a chart comparing the ESC's specs PM fenton06 and I'll get one made and put in here!
Voltage Boosters:
If there are any missing please add them!


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Old 08-06-2003, 12:35 PM   #3586
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What is the reason for using an external Rx pack? I raced 4 cell, 8 minute, stock 1/12th scale cars a few years back and I never used an external pack. At the time I had a Tekin G10 ESC. Is it dependent on the equipment you are using? Is there any benefit if you're not experiencing any problems?
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Old 08-06-2003, 01:07 PM   #3587
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Default reciever pack

It is for 6 volts to the reciever and your steering servo. I don't think the gain in run time is much, but it is a little. the bigger benifit is full power to your reciever all the time even when you are drawing max for the motor. Reicevers run on 6 volts best. just think at 4.8 with a 15 or 20 amp load, the drop must be pretty good especially in mod. The cost is extra weight of course.

I have never run mod so I don't have an issiue of run time.

Getting Fired up , the season starts in october.

David Root
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Old 08-06-2003, 01:25 PM   #3588
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With a receiver pack, you get 6volts to the servo, increasing the speed/torgue and keeping it constant over the 8 minute run.

In mod (even 19 turn or possibly stock), your servo speed will slowly decrease as your voltage and run tim wears down. You will still make time, but oyu will notice a slower reaction in the steering inputs.

For stock or 19t racing, it may not be worth the weight, but I am going to give it a try with very small cells.
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Old 08-06-2003, 05:03 PM   #3589
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Default the red wire

If you disconnect the red wire to from the reciever to the speed control you must turn on the speed control switch to power the speed control. With the red wire in place the speedo's contol cirquitry will run off the reciever pack, and not the BEC ("battery eliminator cirquit", inside the speed control). If you want the sub-C pack to power the motor only, then leave the red wire in place. This is how all the Novak, Tekin and Futaba speed controls that I have used work, I don't know about other brands.

I've never wanted to risk blowing a speed control to see what happens when you turn on both switches, I just put tape over the speed control switch so it can't be turned on (but it's there in case I want to run without the reciever pack).
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Old 08-06-2003, 06:26 PM   #3590
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Originally posted by stormperson
marvi- I know that people make them (IRS or Trinity i think...) for oval cars...
thanks for the info i wanted to try a steel tplate bec 1) my car understeers a bit so i think a stiffer rear end may help and 2) i wreck fiberglass t-plates with amazing regularity so im looking for something stronger oh well, if i cant find something thall fit my rc12, ill just stock up on the fiberglass ones
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Old 08-07-2003, 12:59 AM   #3591
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I was racing my carpet knife for the first time tonight against other 12th scale cars. I was at a big disatvantage for one thing because I only have 2 packs for it, and niether of them are very good. But about 5 minutes into the first qualifying race I came in too tight on the sweeper and broke two of the alumninum hex ball studs that the rear mono links hook onto (they're like a ball stud but a screw screws into it from the bottom of the chassis). So I wasn't able to fix that, so I just raced 19t touring for the rest of the night instead. I was wondering if anyone knew of a company that made that part in steel or titanium. The aluminum ones are just so dang weak . Otherwise I guess I'll just stock up on aluminum pieces .
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Old 08-07-2003, 03:02 AM   #3592
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Default Finish Line Spring Steel Plates


Dx6, I don't think you need steel ball studs, I have never broken one. Just get some new ones, make sure they fit right and spend some time behind the wheel.

A couple more months before I can race my CK.

David Root
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Old 08-07-2003, 03:40 AM   #3593
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how can you survive? 3 more weeks for me! got all battereis, getting motors this week, in process of trueing my tires, and bodyshells are sprayed

can anyone tell me every handling implication of the tbar please, am i right in thinking that a thin one will give less high speed steering and more initial low speed steering? thick one will give less low speed and more high speed?

i wanna know everythin about the tbar, how to select one and also a place online where i can buy every tbar that i need, including both trinity and assocaited sizes.

the car (i dont think it makes a diff) is a trinity sb2002. cheers
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Old 08-07-2003, 04:23 AM   #3594
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David Root: thanks for the link is that steel tplate a direct fit for the RC12L? do i have to buy different hardware to attach it? also, do you know which one (soft, medium, or firm) is similar to the stock fiberglass tplate? thanks in advance for any info
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Old 08-07-2003, 06:19 AM   #3595
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Default Big Thanks!!!

Thanks for all the responses to my question about Rx Packs. I think that it's clear to me now. I don't recall having any issues not using a pack when I raced severa years ago (although, that was racing stock only), so I'm going to take a shot at not using a pack.

Thanks again!

racerdx6: Sounds like you just had a little bad luck. I just got my CK a couple of days ago, and I noticed that the hex balls are now aluminum. I had a CK years ago, and they used to be steel.
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Old 08-07-2003, 08:21 AM   #3596
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Dx- if you had a speedmerchant you would not have to worry about that! lol, jk. I would just make sure that you use a steel screw that is the proper lengh (maybe the one they provided was too short possibly). or you could adapt speedmerchant side links to that car and get rid of the mile high roll center and flimsy piece all together.

also are you runing a front bumper (solid one, not foam), if so remove it, since it causes more problems than it cures. if anything run a small foam bumper the width of the front of the chassis (ie, it doesnt extend infront of the wheels), and it will save your body a little bit, but a hard chassis bumper is a really bad idea in 12th scale, since instead of the body abosorbing the hit gradually it takes it all in one big blow, and you cant glance corners, since the bumper will hit and turn you into the corner.
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Old 08-07-2003, 09:54 AM   #3597
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Default hex balls and side links

I too have broken hex balls on my knife, when I first got it I was hitting more dots than apexes. But it was actually the screw that broke and not the ball itself. Steel screws solved that problem. They aren't red but whatcha gonna do...

Storm-Those screws are really short but they are as long as they can be without bottoming out in the hex balls. The Speedmerchant side links are way better (one of the reasons I'm racing my speedmerchant and not my ck now) but the length is different so you would have to drill new mounting holes in the chassis to use them.
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Old 08-07-2003, 11:28 AM   #3598
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But arn't the speed merchent side links adjustable? So couldn't I just shorten them to use them in the same holes that are already on my ck? The hex balls don't break that often, you really have to hit the corner just right. But they're just so weak, I haven't broken any of my aluminum ball studs yet from racing, but I broke two from screwing the lock nut on the back of them . So I'll either just figure out a way to use the speed merchent side links and adapt that system, or just stock up on the hex balls.
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Old 08-07-2003, 11:42 AM   #3599
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So, what's the benefit of the SpeedMerchant adjustable side links? I thought that the side links were used to set the distince between the rear pod and main chassis??? Are they used to tune the car in other ways?

If not, why not just use fixed links like the ones used on the CK?
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Old 08-07-2003, 12:34 PM   #3600
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Okay, You can use Speedmerchant links on a Carpetknife 3.0 or newer, without drilling new holes. You merely remove the battery brace in front of the cells, and install the forward end of the link in the battery brace anchoring holes. Just that simple. The original Knife actually used these links.

The advantage of the Speedmerchant style links is that they allow much more precise actuation of the rear pod by removing the slop inherent in the one-piece links, and they can be adjusted to compensate for wear. The Carpetknife rear pod is aligned by snapping the side links on, then adjusting the position of the center pivot (football shaped plate) to ensure free movement. With the speedmercant links, the center pivot is fixed, and the length of the side links can be finely adjusted to get just the right feel. The ends of the speedmerchant links are also adjustable. They have a screw which pinches the end closed. as the link wears, you can alter the tension on the link slightly, thereby reducing the slop in the link. The one piece links just wear out and have to be replaced.

I've run both cars, and I prefer the Speedmerchant links.

Just my 2 cents
Team CRC, Access Race Place, US Indoor Champs, CD SUPERPRO, RK Designs, Cypress, Founder and lead instructor of the Ian Ruggles Negative Reinforcement Driver Training Program, enroll now.....
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