1981 GMC Trucks K2500 High Sierra Tires

The 1981 GMC Trucks K2500 High Sierra uses either 8.75R16.5 or 950-16.5, depending on the exact sub-model. Standard High Sierra applications covered here use 8.75R16.5 in radial construction, while Bonus Cab front and rear applications use 950-16.5 in bias-ply construction.

That means the first job is identifying the exact truck configuration rather than choosing between two sizes casually. Both sizes mount on 16.5-inch wheels, but construction and application differ, so the correct choice depends on whether the truck is a standard High Sierra or a Bonus Cab and whether the wheel setup still matches the original style.

The covered tire fitments for a 1981 GMC Trucks K2500 High Sierra use a 16.5-inch rim. That applies to both primary tire sizes on this page, including the 8.75R16.5 radial fitment and the 950-16.5 bias-ply fitment used on Bonus Cab applications.

Rim diameter alone does not settle the whole fitment decision, because the truck may still differ by sub-model and tire construction. It is also worth checking the wheel width, present tire size, and whether the truck has been converted to a different wheel package over the years, since many older pickups have been changed from their original wheel setup.

More than one tire size appears because the 1981 GMC Trucks K2500 High Sierra includes different covered configurations. Standard High Sierra versions use the 8.75R16.5 radial size, while Bonus Cab front and rear applications use the 950-16.5 bias-ply size.

This is why sub-model identification matters before comparing tires. A buyer looking at a Bonus Cab should not assume the radial size applies, and a standard High Sierra owner should not default to the bias-ply truck size without checking the truck's exact configuration, wheel equipment, and any changes made during its working life or restoration.

For the 1981 GMC Trucks K2500 High Sierra Bonus Cab applications covered here, 950-16.5 is a bias-ply tire size. It uses a traditional numeric bias-ply format and appears on both front and rear Bonus Cab fitments rather than on the standard High Sierra radial applications.

That distinction matters because a bias-ply setup brings a different construction choice than the 8.75R16.5 radial used elsewhere in the model line. When replacing 950-16.5 tires, confirm that the truck is truly one of the Bonus Cab configurations and check that the 16.5-inch wheels, wheel width, and overall truck setup still match that bias-ply application.

The right answer depends on the specific 1981 GMC Trucks K2500 High Sierra configuration. Standard High Sierra applications here use 8.75R16.5 radial tires, while Bonus Cab front and rear applications use 950-16.5 bias-ply tires, so the truck's sub-model determines the starting point.

Choosing between constructions should come after confirming what the truck actually uses and whether it still has its intended wheel package. Owners focused on preserving a traditional setup may want to stay with the original construction type for that application, while any change in construction should be checked carefully for wheel compatibility, clearance, and the truck's intended use.

Any conversion on a 1981 GMC Trucks K2500 High Sierra starts with confirming the truck's actual fitment, since the covered applications already split between a radial 8.75R16.5 setup and a bias-ply 950-16.5 setup. A conversion should only be evaluated after verifying the current tire size, wheel diameter, wheel width, and exact sub-model.

The next step is checking whether the truck has adequate clearance at the fenders, steering components, and suspension through full travel. It also helps to inspect for aftermarket wheels, altered ride height, or mixed front-to-rear equipment, because an older three-quarter-ton truck may have seen many changes that affect whether a different construction can be used responsibly.

Start by making sure the truck is one of the Bonus Cab applications that uses 950-16.5. Within that size, the available choices are bias-ply STA truck tires with Blackwall styling, and the main differences come from tire series, rim-width specification, weight, and the way each product suits a traditional truck presentation.

The practical comparison is not just appearance. It also helps to match the tire to the wheel, preserve front-to-rear consistency on Bonus Cab applications, and review load-related specifications such as 2780@60 psi so the tire choice makes sense for the vehicle's intended duty, restoration goals, and present wheel setup.

For the 950-16.5 fitment used on 1981 GMC Trucks K2500 High Sierra Bonus Cab applications, the available products here come from STA. Those offerings are bias-ply truck tires rather than a mix of passenger-car style options, which keeps the selection centered on traditional heavy-duty presentation and use.

Brand choice is only one part of the decision, especially on an older truck with application-specific fitment. It still makes sense to compare the available STA tire series, confirm the wheel width range, and make sure the truck's actual front and rear setup matches the Bonus Cab fitment before settling on a replacement that looks right and suits the vehicle's use.

In the 950-16.5 size used on Bonus Cab applications, the 1981 GMC Trucks K2500 High Sierra has access to the STA Traxion and STA Super Transport series. Both are bias-ply Blackwall truck tires built around a traditional 16.5-inch heavy-duty fitment.

Series choice helps narrow the purchase once size and sub-model are confirmed. Comparing the series side by side lets the buyer look at details such as rim-width suitability, weight, and overall product character, which is useful for a truck that may be restored, lightly used, or kept in a working-truck style rather than treated like a modern pickup.

A period-style choice for a 1981 GMC Trucks K2500 High Sierra starts with the correct application-specific size and construction. Standard High Sierra versions here use the 8.75R16.5 radial size, while Bonus Cab front and rear positions use 950-16.5 bias-ply tires, so preserving the truck's proper fitment comes before comparing brands or series.

Once the size is confirmed, appearance decisions become more meaningful. For Bonus Cab applications, the available 950-16.5 options are Blackwall STA truck tires, which support a traditional heavy-duty look. Buyers chasing exact historical originality should still compare their truck against marque references, factory literature, or long-term ownership history before treating any tire as exact assembly-line equipment.

Tire construction can change the visual character of a restored 1981 GMC Trucks K2500 High Sierra even when the rim diameter stays the same. On this truck, the distinction is clear: some applications use an 8.75R16.5 radial, while Bonus Cab front and rear positions use a 950-16.5 bias-ply truck tire.

That matters because restoration-minded owners often want the tire to match the truck's era and intended stance, not just the wheel diameter. A bias-ply tire usually supports a more traditional truck presentation, while a radial can give the vehicle a different visual impression, so the right choice depends on the exact configuration and how faithfully the truck is being preserved.

Yes. Modifications can affect tire fitment on a 1981 GMC Trucks K2500 High Sierra even when the truck still appears to use the correct size family. Changes such as aftermarket wheels, different wheel widths, suspension lifts, altered ride height, brake conversions, or body work can all influence whether the intended tire still has proper clearance.

That is especially important on a truck that uses 16.5-inch wheels and may have had decades of work-truck updates. A careful check should include wheel diameter, wheel width, steering clearance, and room at the fenders and suspension components so the chosen tire matches the truck as it sits now, not just how it left the factory.

Before road use, inspect the wheels, valve stems, lug hardware, and the overall condition of the suspension and steering on the 1981 GMC Trucks K2500 High Sierra. The tires themselves should be checked for proper inflation, secure bead seating, and any obvious issues such as cuts, bulges, or irregular mounting concerns before putting the truck back into service.

An older three-quarter-ton truck also deserves a quick review of alignment behavior, brake condition, and front-to-rear consistency in size and construction. That extra attention helps catch problems that can make a fresh set of tires feel wrong even when the size is correct, especially on a vehicle that may spend long periods parked between drives.

Tires on a collector-era 1981 GMC Trucks K2500 High Sierra should be inspected regularly for pressure loss, sidewall cracking, tread wear, bulges, and flat spotting from long storage. A truck that is driven infrequently can age its tires in ways that are easy to miss, even when tread depth still looks serviceable.

Storage conditions matter as much as mileage. Keeping the truck away from prolonged sunlight, excess moisture, and ozone sources helps preserve the tires, while periodic movement can reduce flat spotting. It is also smart to recheck wheel hardware and inflation before each outing, since low-use vintage trucks often reveal tire issues only when they return to road use.