tech – Foam Tire Mysteries Explained

With all the different families of foam tire now available for radio-controlled cars it is often difficult figuring out what the compound terminology means and what the differences are. This article is a tutorial that will provide you with the knowledge required to make intellegent decisions on what tire you should be running for your particular application.

Purple, Pink, Grey, Green, R4, F3, Black, Magenta….

What are all these names for foam tires? HELP!

The folks here at CRC are here to explain it all. Read this summary to better understand the various names that tire manufactures attach to the rubber. This will help you decide which tire you need and why.

CRC

Tires are grouped into what we call “families”. These groups are designated based on chemical compounds of the actual rubber/foam mix.

Lets take a look…….

Japanese F

The Japanese rubber primarily used for front tires on asphalt is called Japanese “F”. This rubber is tough as nails with a very high content of rubber and less foam. It wears like iron and is difficult to true and cut. The grip is fairly good but the tough design of the rubber prevents it from biting the surface like some other compounds. Rather than wear off in small chunks or pebbles of foam, this tire is known to melt and get very sticky under high heat. This makes this compound a great choice for asphalt, but not a good choice for carpet. The high friction of carpet racing causes these tires to get “sticky” and pick up grip during the race. If pushed even further, instead of wearing down, this rubber develops a sticky surface picking up debris and actually lowering grip levels.

SoftMediumHardVery HardRocks
Typical Shore <3030 – 3536 – 4242 – 4950+
CRC DesignationF2F3F4F5F6
Other mfgs designation303540 – Red45 – Red 50

Japanese R1/12th Purple fronts for 1/12th scale from CRC

The Japanese rubber typically used for rear tires is Japanese “R” rubber. This rubber has small pore structure and is very high grip and low wear. The rubber is used on the front in carpet racing and as a rear in asphalt racing. This rubber wears more than “F” type, but is much tougher than American or European rubber. When the rubber cures very hard, it makes for an excellent front tire.

SoftMediumHardVery HardRocks
Typical Shore 22 – 2930 – 3536 – 4041 – 4747+
CRC DesignationR2R3R4R5R6
Use for FrontNANAOn CarpetOn CarpetOn Carpet or Asph.
Use on Rear Carpet/AsphaltCarpet/AsphaltCarpet/AsphaltCarpet/AsphaltNot used often
Other mfgs designationPinkMagentaPurplePurpleDouble Purple,X-50

Japanese CCRC Grey mounted rears for 1/12th Scale

Japanese C rubber is typically used for carpet racing. The foam is very light with decent wear. It is tougher than American foam and also has better grip. It does not last as long as F or R rubber.

SoftMediumHardVery Hard
Typical Shore<3333-3839 – 4445+
CRC DesignationWhite – C2Grey-C3Black-C4Double Black-C-5
Use for FrontNANANAOn Carpet or Asphalt
Use on Rear Carpet/AsphaltCarpet/AsphaltHigh bite carpet
Other mfgs designationWhiteGreyBlack

American Rubber

Foam rubber dates back to the early days of racing on foam rubber tires. The foam rubber is very affordable. The compound provides decent grip but the life is low as they are typically high wear. Common names for America foam is green, blue, orange, yellow.

SoftMediumHardVery Hard
Typical Shore <3030 – 3536 – 4545+
CRC DesignationNAGreenGreenBlue
Other MfgsYellowGreenBlueOrange

European/Italian

The Europeans and their love of 1/8th scale gas racing pushed the limits of American foam tires. The European (especially the Italian) companies were eager to find a better tire with more grip and less wear to handle the horsepower of the .21 engines that they were producing. The result is a unique “wet” dense rubber that provides more grip than American rubber on asphalt. The European rubber doesn’t work very well for carpet racing. It is also the heaviest of the foam rubber tires.

SoftMediumHardVery Hard
Typical Shore <3030 – 3536 – 4545+
CRC DesignationSilverGoldNANA
Other MfgsSilver, Gummy BearGold, 70D

Combinations

Sometimes, combining thin rings of 2 different rubber types will give performance features unique to only a dual compound tire. The Orange/Purple combination on the front of a touring car is known as CRC Dual X-firm. These are great for the front on Carpet. Other manufactures designations are Plaid and Orange/purple.

CRC

CRC tire Suggestions


Electric Touring Car – White Dished Wheel

TrackFront 1st ChoiceFront 2nd choiceRear 1st ChoiceRear 2nd choice
High Bite Carpet#2129-26mm Dual X-firm”Plaid”#2134 -26mm R6 “Double Purple”#2135 -26mm R4 “Purple”#2136 – 26mm R3 “Magenta”
Low Bite Carpet#2134 -26mm R6 “Double Purple”#2135 -26mm R4 “Purple”#2136 – 26mm R3 “Magenta”#2135 -26mm R4 “Purple”
High Bite Asphalt#2130 – 26mm F6#2131 – 26mm F5#2135 -26mm R4 “Purple”#2136 – 26mm R3 “Magenta”
Low Bite Asphalt#2132 – 26mm F4#2133 26mm F3#2139 – 30mm R3 #2138 – 30mm R4

Electric Touring Car – Yellow 5-Spoke Star Wheel

TrackFront 1st ChoiceFront 2nd choiceRear 1st ChoiceRear 2nd choice
High Bite Carpet#2114-Dual X-firm”Plaid”#2120 -R6 “Double Purple”#2119 – R4 “Purple”#2117- R3 “Magenta”
Low Bite Carpet#2120 – R6 “Double Purple”#2119 – R4 “Purple”#2117- R3 “Magenta”#2116 -35mm R3 “Magenta”
High Bite Asphalt#2110 – F6#2112 – F5#2119 – R4 “Purple”#2117- R3 “Magenta”
Low Bite Asphalt#2112 – F5#2120 – R6 “Double Purple”#2118 – 35mm R4 “Purple” #2116 -35mm R3 “Magenta”


Nitro Touring Car – White Dished Wheel

TrackFront 1st ChoiceFront 2nd choiceRear 1st ChoiceRear 2nd choice
High Bite Asphalt#2130 – 26mm F6#2131 – 26mm F5#2137 – 30mm R5#2138 – 30mm R4
Low Bite Asphalt#2132 – 26mm F4#2133 26mm F3#2138 – 30mm R4#2139 – 30mm R3

Nitro Touring Car – Yellow 5-Spoke Star Wheel

TrackFront 1st ChoiceFront 2nd choiceRear 1st ChoiceRear 2nd choice
High Bite Asphalt#2110 – F6#2112 – F5#2119 – R4 “Purple”#2117- R3 “Magenta”
Low Bite Asphalt#2112 – F5#2120 – R6 “Double Purple”#2118 – 35mm R4 “Purple” #2116 -35mm R3 “Magenta”


1/12th Scale

1/12th Purple fronts for 1/12th scale from CRCCRC Grey mounted rears for 1/12th Scale

TrackFront 1st ChoiceFront 2nd choiceRear 1st ChoiceRear 2nd choice
High Bite Carpet Road Course#2325 – Purple#2326 – Magenta

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