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.
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.
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.
Soft
Medium
Hard
Very Hard
Rocks
Typical
Shore
<30
30 – 35
36 – 42
42 – 49
50+
CRC
Designation
F2
F3
F4
F5
F6
Other
mfgs designation
30
35
40 – Red
45 – Red
50
Japanese R
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.
Soft
Medium
Hard
Very
Hard
Rocks
Typical
Shore
22 – 29
30
– 35
36
– 40
41
– 47
47+
CRC
Designation
R2
R3
R4
R5
R6
Use
for Front
NA
NA
On
Carpet
On
Carpet
On
Carpet or Asph.
Use
on Rear
Carpet/Asphalt
Carpet/Asphalt
Carpet/Asphalt
Carpet/Asphalt
Not
used often
Other
mfgs designation
Pink
Magenta
Purple
Purple
Double
Purple,X-50
Japanese C
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.
Soft
Medium
Hard
Very
Hard
Typical
Shore
<33
33-38
39
– 44
45+
CRC
Designation
White
– C2
Grey-C3
Black-C4
Double
Black-C-5
Use
for Front
NA
NA
NA
On
Carpet or Asphalt
Use
on Rear
Carpet/Asphalt
Carpet/Asphalt
High
bite carpet
Other
mfgs designation
White
Grey
Black
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.
Soft
Medium
Hard
Very Hard
Typical
Shore
<30
30 – 35
36 – 45
45+
CRC
Designation
NA
Green
Green
Blue
Other
Mfgs
Yellow
Green
Blue
Orange
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.
Soft
Medium
Hard
Very Hard
Typical
Shore
<30
30 – 35
36 – 45
45+
CRC
Designation
Silver
Gold
NA
NA
Other
Mfgs
Silver,
Gummy Bear
Gold,
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.
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