TRUCK SERVICE MANUAL
This will usually result in satisfactory tandem axle
the same manner as the axle housings. Completely
lubricant temperatures that lengthen drive unit service
drain the lubricant while the unit is warm. Flush well with
with higher tire mileage.
clean flushing oil and thoroughly drain. Whenever the
inter-axle differential housing has been drained, always
HOW TO MATCH TANDEM TIRES
add an additional 2 U.S. pints of specified lubricant
directly to the inter-axle differential housing.
The vehicle should be on a level floor, carrying a
correctly distributed rated capacity load. Be sure all tires
Some newer model axles have a smaller tapped and
are the same size. Measure new tires to be sure they
plugged hole located near and below the housing
will be correctly matched.
lubricant level hole. This smaller hole has been provided
for the use of a lubricant temperature indicator only and
A. Inflate all tires to the same pressure.
should not be used as a fill or level hole.
B. Carefully measure the rolling circumference of each
Jack up all four wheels of the assembly and run at 25
tire with a steel tape.'
MP.H. in high transmission gear for five minutes to
thoroughly circulate the lubricant throughout the
C. Mark the size on each tire with chalk and arrange
assembly. Be sure brakes are fully released.
them in order of size, largest to smallest.
D. Mount the two largest tires on one side of one axle
and mount the two smallest on the opposite side of the
Measure the rolling radii of all tires. The tires of all
wheels must be matched to within 1/8" of the same
rolling radius ("' of the same rolling circumference). The
E. Mount the four other tires on the other axle in the
4 largest tires should not be installed on one driving axle
and the four smallest tires on the other driving axle of
thruadrive type tandems. Such tire mounting will cause
F. Test run the vehicle to get accurate rear axle lubricant
inter-axle "fight," unusually high axle lubricant
temperature readings on the two axle lubricant
temperatures that result in premature lubricant
breakdown and possible costly axle service.
G. Vary tire air pressure within the tire manufacturer's
recommended range, so the lubricant temperatures r
circumference, we recommend matching, as nearly as
both axles are within 30°F of each other and not i,
possible, the total tire circumference of one driving axle
excess of 2200F. This will usually result in uniform tire
to the total tire circumference of the other driving axle.
loading and good tire life