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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 02-23-2003, 06:15 PM   #2446
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Thanks, I'm going to get the rev 3.
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Old 02-23-2003, 08:31 PM   #2447
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Thumbs up Re: Re: YRX 12 hard chassis

Originally posted by Apex
You are correct. The .084 thick chassis is the YSP12HC4H
YRX-12 CHASSIS-4 CELL, hard chassis. It looks like Stormer has them in stock now. I got one from Pit Stop Hobbies coming this week.

Yokomo is supposed to come out with a thick SSG chassis quite soon as well.
Thanks for your reply.
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Old 02-24-2003, 03:41 AM   #2448
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Switch Blade: I ran the Hitec 225BB on mine for a while ~$24 stormers. Now I am running the Airtronics 94145Z. Look at the 4.8v ratting not the 6.0v as the cars are 4 cell. Mine works in the futaba R123 reciever and the XXXtra that I have. They will not work in the Futaba HRS receiver. The HRS requires digital servo's and 6.0v.
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Old 02-24-2003, 10:15 PM   #2449
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BigTbone- DaveL gave excellent advice and you may also want to see if your diff is slipping (usually the rings on the diff are slipping). The IRS big ring pinned diff will definately solve this if yours is slipping if you don't have one you would really like it.
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Old 02-24-2003, 11:53 PM   #2450
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I'm building a YRX-12WE right now, and I'm having trouble building the diff. I can't figure out how to make it smooth. I followed the directions closely. I can't put my finger on it.

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Old 02-25-2003, 05:19 AM   #2451
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ok guys maybe you can help me....
i was at the track sunday running 12th...i have an old ae rc12lw.
it was running great, won 12th the other night, but i decided it could be better and i bought an IRS pinned diff and axle assembly and a new vcs shock kit. now the thing traction rolls in every corner! we worked on it the whole day at the track, and maybe just got slightly better but if pushed to anything beyond lazy swooping slow corners, it flips. we (as in 12th guys at the track) have tried front springs, rear springs, diff tightness, and all that, but it still flips. i would like to know your guys thoughts on how i could fix this...
one thing i noticed was that the rear axle is now a bit narrower from the old axle...about a few (3-4) mm one each side as an estimate. now that makes the whole rear 6-8 mm narrower than what it was ! could that be doin it? i put an extra axle shim on both sides to get it spaced so its back where it was but i havnt had any time to run it yet. lemme know what you guys think.
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Old 02-25-2003, 06:30 AM   #2452
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Default Large diff ring


Today, I found new diff ring on IRS page. IRS will release the
Large size diff ring. Someone know the difference between
existing(small) ring and large ring?
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Old 02-25-2003, 06:40 AM   #2453
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bab00n14, is it only flipping one way? (i.e. turning right) ...if so you might have your tweek screws "tweeked"
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Old 02-25-2003, 06:50 AM   #2454
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Default Big Diff vs. Small Diff rings

In my opinion, the smaller diff ring set-up is lighter, but the large diff rings build a smoother feeling diff. I prefer the large diff ring over the small diff rings anyday!!! Escpecially if they are pinned or are a D-ring so diff rings cannot slip!!!
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Old 02-25-2003, 07:32 AM   #2455
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Kiyano - good question about the new large ring differential offered by IRS. The power in 4 cell modified 1.12 scale is insane. The small ring differentials are not showing reliable, consistant ability to hold that power. Depending on the spur gear, the small rings are using either 6 or 8 balls. The large ring differential, when used with a Kimbrough spur gear, offers 12 balls on the outer ring. This combination has done very well in containing the insane power 4 cell modified is applying to the carpet. At least 7 of the A main modified drivers in Cleveland were using the IRS large ring differential. Again at the Snowbirds, I think 7 were using the IRS large ring differential. This combination lasts through the entire event on one build, not counting a crash that messes up the outer bearing. IRS products are offered in your area. Just check around and you can find them.
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Old 02-25-2003, 10:38 AM   #2456
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Darnold & David,

The axel set I have does say big diff ring. ( I got something good and don't know it) However, I am not sure how to pin it. The rings have a little notch/hole in it and the kit came with a yellow stick about 1-2 inches long but no little pin. The yellow stick is too long to place inthe diff.. What am i missing..

Thanks for the help fellas..
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Old 02-25-2003, 11:02 AM   #2457
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Mr. Bone - The yellow rod is a piece of nylon that is to be your pin. Insert it into the hub until there is some sticking out both sides and cut it off. Then do the same thing with the hub on the axle. Now place the ring on the hub or axle and trim the nylon rod to a length that is slightly shorter than the thickness of the rig, but still engages the ring so it won't rotate around the flange or the hub. Your done. Now, assemble the differential, install in the bearings of the car, install the wheels and you are ready to go. After you apply traction to the tires and wipe it off cleanly so it doesn't leave a mark on the carpet, that is.
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Old 02-25-2003, 11:05 AM   #2458
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You'll notice the diff hubs have little holes that will line up with the notches in your rings. You cut the little "stick" in half, insert half into each hub, and secure carefully with a drop of CA (from the non-ring side of the hub).

Once the CA is dry, trim the pins flush with the ring on one side and flush with the back of the hub on the other. Your rings are now pinned.

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Old 02-25-2003, 11:17 AM   #2459
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ummm ok. I think I got it.. I'll try it tonight..THanks so that stick can last a while huh? I think I got messed up when I looked at pin hole and saw that it could not go straight through to the other side because of the sput gear.. also now I realize that I should have put the balls in the outer ring of the gear.. or am I still confused?

dang maybe I should have stuck with sedan... Never knet such a simple looking car could be *********
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Old 02-25-2003, 11:18 AM   #2460
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ok I figures ome more thing out the yellow thing should not go all the way through should be cut flush.. Now I got it... Yeah call me slow.....
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