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Old 08-01-2002, 11:37 AM   #46
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Default Re: Traction Compound.

I use TQ8 on rubber tires. Works great.
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Old 08-02-2002, 06:28 AM   #47
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Could someone please give me the theory behind foam tyres as they are not something I have ever come across before.
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Old 08-02-2002, 06:53 AM   #48
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you have never come across foam tires before ????

I suppose the theory is simply that they are softer and therefore should in good conditions offer more grip than rubber, at the expense of a higher wear rate.

This however is overcome by the fact that foam tires can be solid, because of their low density (ie low rotating mass) and therefore with a reasonably even wear rate can be used from new until there is almost no foam left on the rim, with very little variance in performance. The downside of this is having to change ride height and gearing to compensate for the changing tire size.

Foam also has less susceptibility to tempreture variance.
It can also sometimes "chunk" which can affect handling.
It also isn't as effective on less than ideal surfaces.
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Old 08-02-2002, 06:54 AM   #49
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btw, foam tires have varying amounts of rubber in them as well.
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Old 08-02-2002, 07:32 AM   #50
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Sorry, I should have worded that better. I have seen them being used on 1/12th cars, but I have never used them myself. Perhaps 'experienced' would have been a better word to use. Here in England rubber tyres are preferred, even for 1/10th 200mm nitro.

I notice that all foams are sold in different 'shores' or with reference to colours. What is the difference and could someone explain which colours/shores are the hardest and which are the softest.
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Old 08-02-2002, 11:28 AM   #51
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university_dave

There are many different ways that foam tires are measures. There really isn't any good cross reference that says double puple from Jaco is the same as 42 shore from Ellegi or anything like that. Basically, the ratings are a measure of hardness and durability. My suggestion would be to pose this question to the forum for the type of car you race. There is likely a forum on this board. There will be people that race your car on foams and can share their experiences with you. Scope out the brands of tires that your lhs carries so you can ask for comparisons. You want to run with no more than 5 shore difference from front to rear, so you will likely have to change the setup on your car to make this work. If the tires are rated by color dots, you don't want to go more than one color dot difference (double purple rear/red front) from front to rear. It is also helpful to have access to a tire truer if you plan to race competitively on foams. Once you get your car set up to run on foams, you won't go back to rubber!
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Old 08-02-2002, 05:25 PM   #52
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Here in the US, the primary tire makers (BSR, TRC, Jaco, etc.) rate tires in color dots. This corresponds to the individual tiremaker's own shore (hardness) rating. For example:
  • Yellow (20c)
  • Green (25c)
  • Black (25c)
  • Blue Rear (30c)
  • Blue Front (40c)
  • Purple (40c)
  • Dbl Purple (40c)

BSR and TRC are similar.

I believe that they use colors to differentiate between normal (like green) and exotic (like black) especially when they have the same hardness rating.

Other than that, I don't know. The color ratings are consistent, though, from pan car through sedans. . .
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Old 08-06-2002, 01:17 PM   #53
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OK guys, after surveying the posts, I didnt see anything about my one major concern...I have very limited experience with foams, but after three weeks these darn things come to pieces...I have one foam that looks like frankentire...chunks glued back into it...Am I doing something wrong here? Do you guys get good life on foams?

Up until recently I ran exclusively rubber tires, and was able to get many runs out of a set of tires. Now we are moving to an asphalt parking lot track, and I hear the guys are running foams, and the thought of foams on asphalt and the wear and chunking scares me to death.

Any comments?
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Old 08-06-2002, 03:38 PM   #54
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Hmmm, chunking. Nowdays I run Ellegi foam tires 35 shore for the rear (EVI4C) and 37 shore for the front (EVI4D) on outdoor medium grip asphalt tracks. Ellegi provides a sticker made from aluminium to place on the sidewall of the tires. This reduces the chunking. Actually I have no chunking with these tires. I have used before different foams for indoor racing, and my opinion is that chunking is a matter of tire quality. May be your foams are not up to the task.

BTW: you can rebuild a foam wheel with new foam very cheap. Buy 1:8 scale gas car rear foam donuts (2 pcs) than cut in two , glue onto the rim and trim it with a tire truer. Works great, and those Ellegi foams are absolutely the highest quality.
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Old 08-07-2002, 10:50 AM   #55
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markg

Chunking tires definitely sux. Here's a couple things that may help. Stay off the boards! Seriously, I'm not bashing, but that's how I chunk most tires. I race electric F1 with foams and it seems like whenever I get tangled up with a sedan during practice, a tire gets cut or chunked. If you bevel the edges well on the tire truer it helps reduce chunking since the rounded edge doesn't catch on things as easily and it lets the rim do most of the rubbing. You can also try spreading a thin coat of shoe goo on the outside edge of each tire to take some of the impact. Once you get the hang of driving with foams, you won't chunk tires as often.
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Old 08-07-2002, 11:01 AM   #56
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psycho...I think that is the real problem...we were racing on a very tight carpet track with little room to maneuver, so there were frequent tangles. I imagine it was the tie-ups that caused the cuts, which ended up becoming the chunks...my esperience with rubber tires is that they were a lot more forgiving in this area, but didnt have the traction...

The other thing I noticed running foams was I broke more front suspension parts...I attribute it to the wider tires, and more traction stressing the front end parts more...I dunno...maybe just a run of bad luck...

Anyway, thanks for the responses...
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Old 08-07-2002, 02:41 PM   #57
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Hmmm... I've never noticed that I break more parts with foams then with rubber, so I'd bet that just coincidence. Could be that since you have more grip, you're over cooking turns and getting into more trouble. You didn't say what class you're running, but if you're running sedan or pro-10 make sure the body never comes into contact with the tires. I usually push the body in, sort of simulating various types of hits, to make sure that the body never touches any of the tires. If it does, it will cause the car to push and can cut the tire as well. Get in the habit of looking 4 or 5 car lengths ahead of your car instead of look at your car. That will help you avoid trouble too. Good luck!
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Old 08-09-2002, 12:20 PM   #58
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This will probably sound very pro-foam, but I'm having trouble with my rubber. Just thought I'd post here rather than make a new post.

Anyways, I destroyed a rim (while running with the 540 silver can thing, ). The tires are still perfectly usable, they're Tamiya Type As with the shaped rubber inserts, so I want to remove them from the rim. I've heard about boiling the things but have never had to do it, so I gave it a try with some older wheels. It didn't work! I ended up with warped rims (the heat warped the friggin' rims), and the CA remains strong.

So, what can I do to get my tires off? Am I boiling them wrong? And, is there any effort required to remove the tires after boiling? When I tried to remove the rubber I ended up ripping the edges and leaving trace bits of rubber on the rim.

If it makes any difference, I used ZAP CA by Pacer.

Thanks.
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Old 08-09-2002, 12:31 PM   #59
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ISO - if you want to keep the rubber AND the inserts, you're up a creek. If you keep the rubber, you're gonna lose the inserts. If you keep the inserts, you're gonna lose the rubber 'cause you have to cut them out.

Soak them in Lacquer Thinner or Acetone overnight. It will leave the rubber fine and, if you are using Nylon rims, it will leave them fine too, but it eats the inserts. It will dissolve the CA - it takes a while though. . .and then you can just clean them up.

Come to think about it, if you didn't want the rims, you could just tear them up and get the inserts out. . .
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Old 08-09-2002, 10:24 PM   #60
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Thanks Boomer,

Guess I'll cut out the inserts and buy new rims and tires.

But then what the heck does boiling even do? I'm sure I've seen boiling as a tech tip at some sites, or even in RCCA mag. Not to mention seeing people mention it in posts and whatnot.
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