What The Number Means
8PK1485 is a metric micro-V belt code, not a brand catalogue number. The 8 is the rib count. PK is the metric profile with 3.56 mm rib spacing. The 1485 is effective length in millimetres. Any belt built to that code runs the same pulley grooves and the same span, which is why the number travels across brands instead of belonging to one.
This one is sold as an aftermarket direct replacement for Detroit diesel accessory drives. It carries the same rib count, profile and length as the belt it replaces, so it seats in the alternator, water pump, fan and A/C pulleys without spacers or bracket changes.
Construction matters more than the number once it's on the truck. Look for a reinforced tensile cord and an EPDM-type rib compound. Heavy-duty accessory drives run hot, run long hours, and cycle the tensioner constantly. A belt that hardens early cracks between the ribs and starts chirping before it lets go.
Why These Numbers Cross
The Gates listing 21556636 crosses to 8PK1485 because both describe a belt with eight PK-profile ribs and a 1485 mm effective length. Manufacturers assign their own internal numbers for stock control, but the geometry underneath is fixed by the same metric standard. Same rib count, same pitch, same length means the same groove engagement and the same wrap around the drive.
That's the whole logic of a belt cross-reference. Unlike a casting or a housing, a serpentine belt has no mounting ears or port locations to differ. If length and rib profile match, the part interchanges. The other brand numbers exist purely to identify the belt in that supplier's system, and are listed here for identification only.
PartStop is not affiliated with, endorsed by, or authorised by any of these manufacturers. Use the cross-reference as a starting point. Fitment is confirmed by the number printed on the old belt, or by VIN against your engine's accessory drive layout, before you order.
Check Before You Order
Pull the old belt and read the back. Most belts carry the metric code moulded into the cover, and that's the fastest confirmation you're on the right length. If the printing is gone, count the ribs and measure the belt laid flat around a tape, then compare. A rib count of eight is the first gate — a seven or ten-rib belt will not run.
Then inspect what killed the last one. Chunked ribs and a polished glaze usually point at a tired tensioner or a seized idler, not a bad belt. Rolled edges or a belt that walks off a pulley means misalignment. Replace the belt into a worn drive and you'll be back under the hood shortly. Spin every idler by hand and check the tensioner arm for slop.
8PK1485 Cross-Reference & Interchange Numbers
These manufacturer and aftermarket numbers commonly cross-reference to 8PK1485. 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 |
|---|---|
| Gates | 21556636 |
Frequently asked questions
Is 21556636 the same belt as 8PK1485?
They cross to the same specification — eight PK-profile ribs at 1485 mm effective length. The numbers come from different cataloguing systems but describe the same belt geometry. Confirm against the code on your old belt or by VIN before ordering, since accessory drive layouts vary by build.
How do I measure a serpentine belt if the printing has worn off?
Count the ribs first, then measure the length. Lay the belt flat and run a tape along the outer surface, or route a piece of string through the drive path with the tensioner at working position. Compare the result to 1485 mm. Rib count must match exactly — length tolerance is tight but not zero.
Why did my last belt only last a few months?
Short belt life on a heavy-duty drive is almost always a component problem, not a belt problem. A weak tensioner spring lets the belt slip and glaze. A dry idler bearing puts a hot spot on the ribs. Misaligned pulleys roll the edges. Check all three before installing the replacement.
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.