How do I find out what gear ratio my Silverado has?
The quickest way to know your Silverado's gear ratio is to read the axle specification on the driver’s door jamb sticker or the original window sticker. If those labels are missing, you can decode the VIN or inspect the rear differential tag to confirm the ratio.
Where to look on the vehicle
The following sources are the most reliable for identifying your rear axle ratio without tearing into the drivetrain. Start with the easiest-to-access label first, then move to build data if needed.
- Driver-side door jamb placard: The door sticker often lists the axle or rear axle ratio (for example, “Axle 3.73” or “Axle 3.42”). This is the quickest in-vehicle source.
- Original window sticker (Monroney label): On new trucks, the window sticker shows the axle specification under the equipment or options section. This is the factory-installed figure for the exact vehicle.
- Rear differential tag or housing stamping: Some Silverado models have a small tag on the differential housing or a stamped code on the cover that indicates the gear ratio (e.g., 3.73, 3.42).
- VIN-based build sheet or RPO code lookup: The factory build sheet or a decoded VIN can reveal axle information via the RPO codes associated with your truck’s order. This may require dealership access or an online VIN decoder.
- Dealer or service department lookup: If you’re unsure or the labels are missing, a Chevrolet dealer can pull the exact axle ratio from GM’s databases using your VIN.
Using these sources will give you the exact axle ratio for your Silverado, which is essential for towing calculations, gearing decisions, and fuel-economy planning.
VIN decoding and labels: How to read them
VIN decoding can reveal manufacturing details, including axle information, if the vehicle’s RPO codes include an axle specification. Use a GM VIN decoder, the dealer’s systems, or trusted third-party decoders to pull the data. The key is to locate the axle-related code and translate it to the numeric ratio used for gear calculations.
Using the VIN for axle data
When you decode your VIN, look for an axle-related code or an entry under drivetrain options that corresponds to the rear axle ratio. Many sources will provide a direct numeric value (for example, 3.23, 3.42, 3.73, 4.10) or a code that maps to one of these common ratios. If the decoder only returns codes, cross-reference them with GM’s RPO code lists to convert them to a final gear ratio.
Limitations of VIN decoding
VIN decoding is generally reliable but can vary by model year and trim. If the result is unclear or you have a highly optioned vehicle, confirm with a dealer or pull the original build sheet for the definitive ratio.
Regardless of method, once you have the axle ratio, you’ll have a clear picture of your Silverado’s gearing and how it impacts performance and towing.
Manual ways to determine the ratio (last resorts)
If you cannot access stickers or VIN data, you can measure the ratio directly. These methods require careful setup to avoid injury or fluid leaks, and are more hands-on than label-based methods.
- Drive shaft rotation method: With the vehicle safely lifted and in neutral, rotate the driveshaft one full turn and count how many times the rear wheels turn. The gear ratio is approximately the number of driveshaft turns per one wheel revolution (Gear ratio ≈ driveshaft revolutions / wheel revolutions). This method is simple but may be less precise due to tire slip and measurement error.
- Differential-teeth method: Remove the differential cover (or access the ring gear and pinion teeth through a service window) and count the teeth on the ring gear and the pinion gear. The ratio is ring gear teeth divided by pinion teeth (ratio = ring teeth / pinion teeth). This method is precise but requires proper sealing afterwards and some mechanical know-how.
- Note on accuracy: Both methods require that the vehicle be stationary, properly supported, and that you avoid contact with moving parts. If you’re unsure, rely on labels or a dealer lookup for an exact figure.
Manual methods can verify or supplement label and VIN data, but are more involved and should be done carefully to avoid damage or injury.
What the numbers mean for your Silverado
Gear ratios tell you how hard the engine must work at a given speed. A lower numerical ratio (e.g., 3.23) generally favors fuel economy at highway speeds, while a higher numerical ratio (e.g., 4.10) provides stronger acceleration and better towing performance but can reduce highway efficiency. The exact ratio is influenced by drivetrain configuration (2WD vs. 4WD), engine choice, and whether the truck is a heavy-duty variant. Knowing your ratio helps with towing planning, axle life estimates, and selecting appropriate tires and gearing upgrades if you’re modifying the truck.
Summary
To determine your Silverado’s gear ratio, start with the easiest sources: the driver’s door jamb sticker and the original window sticker. If those aren’t available, use the VIN to pull the build sheet or consult your dealer to confirm the axle ratio. You can also inspect the rear differential tag or perform careful manual measurements, though these methods require more effort and care. Armed with the exact ratio, you can better plan towing capacity, fuel economy, and any gearing-related upgrades.
