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Guidelines for Specifying the Correct Kits for the Meritor Tire Inflation System
(MTIS™) by PSI™
As the leading automatic tire inflation system in North America, the Meritor Tire Inflation System (MTIS™)
by PSI™ is designed to be compatible with a wide range of axle and wheel-end component combinations. To
help ensure that you specify the correct MTIS kit for an application, Meritor is pleased to provide the following
guidelines concerning the length of the thru-tee tube, which depends on the type of axles and wheel-ends on the
trailer.
For Installation on Meritor TN/TQ Axles with Tapered Spindles
Specify kits having thru-tee assemblies with 3.5” long tubes when the trailer axles are equipped with ductile
iron hubs. If the trailer axles are equipped with aluminum hubs, specify an MTIS kit containing thru-tees with 4”
long tubes.
For Installation on Meritor TP Axles with Parallel Spindles
Specify kits having thru-tee assemblies with 4” long tubes when the trailer axles are equipped with ductile iron
hubs. If the trailer axles are equipped with aluminum hubs, specify an MTIS kit containing thru-tees with 5”
long tubes.
MTIS Kit Part Numbers
“Partial” MTIS Kits
“Partial” kits do not include spindle press plugs or stators. Partial kits are for installation on axles prepped for MTIS. (The spindle press plugs and
stators have been installed on the axles.)
Note that the standard thru-tee length for partial MTIS kits is 3.5”. If you require a longer thru-tee length, please inform your Meritor customer
service representative when placing your MTIS order. When a length other than the standard 3.5” is specified, it will be stated in the kit part number.
Refer to the following table for examples.
(Thru-tee Tube Length)
Trailer Axle and Hub types
Recommended
Thru-Tee Tube
Length
Standard MTIS Kit
Number Example
MTIS with
ThermALERT™ Kit
Number Example
TN axle with ductile iron hubs
3.5”
32712-22
H2712-22
TN axle with aluminum hubs
4”
32712-22-4
H2712-22-4
TP axle with ductile iron hubs
4”
32712-22-4
H2712-22-4
TP axle with aluminum hubs
5”
32712-22-5
H2712-22-5
“Full” MTIS Kits
“Full” MTIS kits are for installation on axles not previously prepped for MTIS. These kits include spindle press plugs and stators.
The standard thru-tee tube length for a full MTIS kit is based on the spindle type for which the kit is intended. For example, a full MTIS kit for a TN
axle will have a standard thru-tee tube length of 3.5,” while a full MTIS kit for a TP axle will have a standard thru-tee tube length of 4”.
If you require a thru-tee length longer than the standard length, please inform your Meritor customer service representative when placing your MTIS
order. When a length other than the standard is specified, it will be stated in the kit part number. Refer to the table below for examples.
Axle / Spindle Type
Hub Type
Recommended
Thru-tee Tube
Length
Example Standard
MTIS Kit Number
Example MTIS with
ThermALERT™ Kit
Number
TN/TQ, HN
Ductile Iron
3.5”
31965-22
H1965-22
TN/TQ, HN
Aluminum
4”
31965-22-4
H1965-22-4
TP, WP, HP (2.75” bore) Ductile Iron
4”
31975-22
H1975-22
TP, WP, HP (2.75” bore) Aluminum
5”
31975-22-5
H1975-22-5
Please contact your Meritor representative for assistance to obtain the correct kit for the application. You can also access product and service
information on the Meritor Tire Inflation System (MTIS) in the Literature On Demand section of www.Meritor.com.