1981 GMC Trucks K2500 Sierra Grande Tires

The 1981 GMC Trucks K2500 Sierra Grande uses two different primary tire sizes depending on configuration: 8.75R16.5 radial or 950-16.5 bias-ply. Standard Sierra Grande versions in this coverage use 8.75R16.5, while Bonus Cab front and rear fitments use 950-16.5.

That means the first job is identifying the exact sub-model before choosing a tire. Both sizes mount on 16.5-inch wheels, but they are not the same fitment, and the construction type changes with the size. A truck that has had wheel, axle, or suspension changes over the years should be checked carefully before replacement.

The covered tire fitments for the 1981 GMC Trucks K2500 Sierra Grande use a 16.5-inch rim. That is true for both the 8.75R16.5 radial fitment and the 950-16.5 bias-ply fitment used on the Bonus Cab configurations.

Knowing the wheel diameter helps narrow the search, but it does not settle the whole fitment question. The truck still needs the correct tire size for its configuration, and wheel width matters as well when comparing available products. Any replacement wheel or aftermarket setup should be measured rather than assumed, especially on an older heavy-duty truck.

No. The covered sub-models do not all share the same tire size. Standard 1981 GMC Trucks K2500 Sierra Grande configurations use 8.75R16.5 radial tires, while the Bonus Cab front and rear configurations use 950-16.5 bias-ply tires.

That difference matters because a buyer can arrive at the right wheel diameter and still choose the wrong tire. The exact sub-model, including whether the truck is a Bonus Cab configuration, should be confirmed first. On older trucks, it is also smart to inspect the wheels already on the vehicle in case the original setup has changed over time.

Start with configuration and construction. On the covered Bonus Cab fitments, 950-16.5 is a bias-ply tire on a 16.5-inch wheel, so the correct choice begins with staying in that size and making sure the wheel matches the intended tire. Available options also share a truck-oriented character rather than a passenger-car presentation.

From there, compare details that affect use and appearance, including tire series, blackwall styling, rim-width compatibility, and load figures. The available 950-16.5 options fit 6.50 to 6.75-inch rims and carry the same 2780@60 psi load specification. That makes series preference and intended truck use the more meaningful points of comparison.

For the covered 950-16.5 fitment on the 1981 GMC Trucks K2500 Sierra Grande, the available product choices come from STA. Those options include the Traxion and Super Transport series, both built as bias-ply truck tires for the Bonus Cab fitment.

Brand alone should not be the whole decision. Once the correct size and construction are confirmed, compare the series within that brand to match the truck’s intended use and the look you want to maintain. It also helps to verify wheel width before ordering, since a heavy-duty pickup may no longer be running its original wheels.

The available 950-16.5 bias-ply choices for the 1981 GMC Trucks K2500 Sierra Grande include the STA Traxion and STA Super Transport series. Both are blackwall truck tires built for a 16.5-inch rim and share the same load and rim-width specifications.

That means the series decision is less about basic fitment and more about the kind of truck presentation you want within the correct size. Owners keeping a work-truck or restoration-oriented look may compare the two series on tread character and overall style, while still making sure the Bonus Cab configuration is the one that uses 950-16.5.

A period-style choice starts with the exact configuration. Standard Sierra Grande versions in this coverage use 8.75R16.5 radial tires, while Bonus Cab front and rear fitments use 950-16.5 bias-ply tires. Matching the truck to the correct size and construction is the most important first step in preserving an authentic overall presentation.

Appearance decisions come after fitment is settled. For the 950-16.5 Bonus Cab application, the available products are blackwall STA truck tires in the Traxion and Super Transport series, both suited to a traditional heavy-duty look. When exact restoration accuracy matters, vehicle-specific literature and marque expertise remain the best final check.

Yes, correct tire fitment matters because this truck does not use one universal setup across the covered configurations. A restoration that overlooks the difference between the 8.75R16.5 radial fitment and the 950-16.5 bias-ply Bonus Cab fitment can end up with the wrong construction or the wrong overall look for the vehicle.

Proper fitment also affects stance, wheel compatibility, and how convincingly the truck presents as a finished restoration. Even when the wheel diameter is the same, construction and size still need to match the truck’s exact configuration. A careful restoration should confirm sub-model details and inspect the actual wheels on the vehicle before selecting tires.

Yes. Modifications can change what works on a 1981 GMC Trucks K2500 Sierra Grande even when the original fitment is known. Aftermarket wheels, suspension changes, lift or lowering work, brake conversions, and body alterations can all affect how an 8.75R16.5 or 950-16.5 tire sits on the truck.

A truck that has been changed from stock should have wheel diameter and width checked before choosing a replacement tire. Clearance at the fenders, steering components, and suspension travel also deserves attention. Older heavy-duty pickups often accumulate parts from different years, so a hands-on inspection is more reliable than assuming the truck still matches its original setup.

Before road use, inspect the wheels for damage, make sure the tire size matches the truck’s exact configuration, and confirm that the tires are seated properly on the correct 16.5-inch rims. Lug hardware, valve stems, inflation, and visible clearance around the wheel openings and steering components should also be checked.

An older K2500 should also be looked over for suspension wear, loose steering parts, and signs that the wheels or tires contact the truck under movement. A short, careful test drive can reveal pulling, rubbing, or vibration before the truck goes farther from home. That kind of inspection is especially worthwhile on a collector or long-stored vehicle.

Collector-truck tires should be maintained with regular pressure checks, visual inspections, and clean storage conditions. The tires on a 1981 GMC Trucks K2500 Sierra Grande should be watched for cracking, bulges, cuts, uneven wear, and slow air loss, especially if the truck spends long periods parked or only comes out occasionally.

Storage conditions matter as much as mileage on an older truck. Keeping the vehicle away from prolonged sunlight, excess heat, standing moisture, and ozone sources can help preserve tire condition over time. It also helps to inspect the tires before each drive rather than assuming low annual mileage means they are ready for service.