What This Air Spring Does
This is a cab/sleeper mount air spring, not a chassis or drive axle bag. It sits between the cab or sleeper floor structure and the frame rail, carrying the isolated cab and damping the road input the chassis suspension does not absorb. When it works, the driver feels a floating cab. When it fails, every expansion joint comes straight through the seat.
Physical spec on the PartStop unit: single-stud top, single-stud bottom, roughly 8.1 inches extended and 2.4 inches collapsed, rated to 100 psi. The reversible-sleeve design rolls the rubber over the piston instead of flexing a convoluted bellows, which is why the collapsed height is so short and why it tolerates the constant small movements a cab mount sees.
Failures are usually mechanical, not electrical. The sleeve chafes where it rubs a bracket or a routed air line, or ozone and road salt crack the rubber near the bead. Cold-weather splits are common on high-mileage sleepers. You will hear an air leak at idle, or find the cab sitting low and cocked to one side after an overnight shutdown.
Why These Numbers Cross
W02-358-7207 is a Firestone catalog number that was superseded to W02-358-7215. Same air spring family, same mounting geometry, same working heights — the supersession reflects a Firestone catalog change, not a different part on the truck. If your old bag is stamped W02-358-7207 and the box on the shelf says W02-358-7215, you are looking at the same application.
From there the crosses follow the same assembly through other catalogs. Goodyear lists it as 1S5-175. ContiTech carries 68161 and CB7215. Freightliner's own service number is 18-40977-000. Aftermarket suppliers publish FS7215, TR7215 and AS-7215 against the same application. All of these numbers are listed here for identification only — PartStop is not affiliated with or authorized by any of these manufacturers.
The common thread is the mounting interface and the height range: single stud top, single stud bottom, short collapsed height, reversible sleeve. Two air springs with different stud counts or a different piston diameter will not interchange even if a catalog groups them loosely. Match the studs and the extended height before you accept any cross.
Check Before You Order
Pull the old bag and read the number molded or stamped into the end cap or the crimped ring. That number, or your VIN, is what confirms fitment. A cross-reference list is a starting point only — Freightliner ran more than one cab suspension configuration across the Cascadia (2008-2018), Columbia (2001-2016) and Century (1999-2010) production runs, and sleeper mounts do not always match cab mounts on the same truck.
Also check what killed the old one. If the sleeve was cut, find the bracket edge or the air line that was rubbing and fix it, or the replacement goes the same way. Inspect the height control valve and its linkage while the bag is out; a stuck valve overinflates the spring and works the rubber past its design travel.
W02-358-7207 Cross-Reference & Interchange Numbers
These manufacturer and aftermarket numbers commonly cross-reference to W02-358-7207. Use them to identify the part — then confirm the exact fit by VIN or the number stamped on your old unit before you order. An interchange is a starting point, not a fitment guarantee.
| Brand / Line | Cross-Reference Numbers |
|---|---|
| ContiTech | 68161, CB7215 |
| Firestone | W02-358-7215 |
| Freightliner | 18-40977-000 |
| Goodyear | 1S5-175 |
| Meritor | FS7215 |
| Torque | TR7215 |
| Triangle | AS-7215 |
Frequently asked questions
Is W02-358-7207 the same as W02-358-7215?
W02-358-7207 was superseded to W02-358-7215 in the Firestone catalog. The two numbers describe the same cab/sleeper air spring application with the same mounting and height range. If your old bag reads W02-358-7207, the 7215 number is the current reference. Confirm against the number on the removed part before ordering.
How do I know if the cab air bag is leaking or the height valve is bad?
Air the system up, shut the truck down, and spray the bag and its fittings with soapy water. A split sleeve will bubble at the tear or seep along the bead. If the bag holds but the cab never comes up to ride height, or sits too high, look at the height control valve and its linkage arm instead.
Will this fit my Cascadia sleeper?
It is listed for Freightliner Cascadia, Columbia and Century cab and sleeper air mounts, but we cannot promise fitment from the model alone. Cab mount and sleeper mount springs can differ on the same truck. Verify with your VIN or the number stamped on the old air spring, and check the mounting studs and ride height.
Not sure it fits? We check before you pay.
Run your VIN and we’ll match parts to your exact truck, or call the counter — a person who knows trucks verifies fitment by OEM number before the order ships. No wrong-box returns.
More cross-reference guides
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Every part below is a Premium Quality aftermarket Direct Replacement with published OEM cross-reference numbers, a 6+ month warranty and same-business-day shipping from Tacoma, WA. Not sure it fits? Run your VIN — or call and a person who knows trucks will verify fitment before you pay.