Proper
wheel selection is a very important component of your trailer gear
system. When replacing your trailer tires/rims it is critical that the
proper size and load range be selected in order to match the load
requirements of the trailer. The following characteristics are
extremely important and should be thoroughly checked when replacing
trailer tires.
-
TIRE CONSTRUCTION TYPE - Bias Ply vs. Radial
-
TIRE APPLICATION TYPE - (ST) Special Trailer vs. (P) Passenger Car
-
TIRE SIZE - % of section height / section width Refereed to as 'Aspect Ratio'
-
TIRE LOAD RANGE - Load carrying capacity and air pressure rating
-
RIM SIZE - Diameter and width must match tire
-
RIM BOLT CIRCLE - Diameter of bolt circle must match hub
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Quite
often consumers are uncertain how to read or interpret specifications
on a tire side wall. This problem is compounded by the Trailer Tire
Industry's use of three different size identification systems on
trailer tires. The following are examples and explanations of tire code.
-
THE
NUMERIC SYSTEM - (4.80 X 8) mostly used on smaller trailer tires,
indicates the tire section width (4.80"), and the rim diameter (8")
-
THE
ALPHA NUMERIC SYSTEM - (B78 X 13 C) common on 13"-15" trailer tires,
indicates air chamber size (B), the 'Aspect Ratio' (78), the rim
diameter (13"), and the load range (C)
-
THE
METRIC SYSTEM - (ST205 75D 15) currently being phased in by trailer
tire manufacturers, indicated the tire application type (ST-special
trailer), the section width (205mm), the 'Aspect Ratio' (75), the
construction type (D= bias ply), and rim dia.(15")
Proper
rim selection is also important to assure replacement wheels will match
your existing trailer hardware. Be certain to match your wheel 'bolt
circle' pattern to the axle hub. The bolt circle is determined as
follows:
Tire
'load range', or the maximum weight each tire can safely support, must
be considered when selecting the proper size tire for your application.
The load range and maximum weight capacity are indicated on the tire
side wall.
-
LOAD RANGE B = OLD 4 PLY RATING
-
LOAD RANGE C = OLD 6 PLY RATING
-
LOAD RANGE D = OLD 8 PLY RATING
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