The 1980 GMC Trucks C2500 Sierra Grande sits in the square-body era, a time when GMC heavy-duty pickups balanced work-truck durability with more upscale trim and broader everyday use. That makes tire choice especially important, because this exact truck can use several different sizes depending on GVWR, stud configuration, and wheel setup. Primary fitments here include radial 7.50R16, 8.75R16.5, and 9.50R16.5 applications, along with a 950-16.5 bias-ply fitment on certain configurations. The main decision is confirming the exact sub-model and wheel diameter first, then selecting a tire that matches the truck's intended use, appearance goals, and period-appropriate character.
Which Tire Size Is Right for The 1980 GMC Trucks C2500 Sierra Grande
The 1980 GMC Trucks C2500 Sierra Grande uses four primary tire sizes, and the right one depends on the exact sub-model, GVWR, stud configuration, and whether the truck is running a 16-inch or 16.5-inch wheel. Before choosing a tire, confirm the specific sub-model and wheel diameter, because this fitment range includes both radial and bias-ply applications across two different rim diameters.
Fit(s): (7/16 & 1/2 inch studs)(GVWR 6400) and (9/16 inch studs)(GVWR 6400)
Construction: Radial|Rim: 16 in
7.50R16 is a vintage-style radial size that uses a nominal 7.5-inch section width, radial construction, and a 16-inch rim diameter. On this GMC C2500 Sierra Grande, it belongs to selected 6400 GVWR configurations rather than every version of the truck. Its radial construction makes it distinct from the 16.5-inch bias-ply application used elsewhere in the range. This size is the one to evaluate when the truck retains a 16-inch wheel setup and the goal is to stay aligned with the proper radial fitment for that specific configuration.
Fit(s): (7/16 & 1/2 inch studs)(GVWR 6400) and (9/16 inch studs)(GVWR 6400)
Construction: Radial|Rim: 16.5 in
8.75R16.5 is a radial size with an 8.75-inch nominal section width and a 16.5-inch rim diameter. It appears on selected 6400 GVWR versions of the 1980 GMC Trucks C2500 Sierra Grande, so it should not be treated as universal across all sub-models. The size combines vintage truck sizing language with radial construction, making wheel-diameter confirmation especially important before purchase. This is a practical fitment to review when the truck has 16.5-inch wheels but does not use the heavier-duty 950-16.5 bias-ply setup found on certain other configurations.
Fit(s): (7/16 & 1/2 inch studs)(GVWR 6400) and (9/16 inch studs)(GVWR 6400)
Construction: Radial|Rim: 16.5 in
9.50R16.5 is a radial truck size built around a nominal 9.5-inch section width and a 16.5-inch rim diameter. For the 1980 GMC Trucks C2500 Sierra Grande, it is used on certain radial-equipped 6400 GVWR configurations and shares its rim diameter with other 16.5-inch fitments, but not its construction with the 950-16.5 bias-ply application. That makes the exact size code just as important as the wheel diameter. This size deserves a close look when maintaining a period-style heavy-duty stance on a radial-equipped truck with the correct 16.5-inch wheel setup.
Fit(s): (7/16 & 1/2 inch studs)(GVWR 8600), (9/16 inch studs)(GVWR 8600), Bonus Cab (7/16 & 1/2 inch studs) Front, Bonus Cab (7/16 & 1/2 inch studs) Rear, Bonus Cab (9/16 inch studs) Front, and Bonus Cab (9/16 inch studs) Rear
Construction: Bias Ply|Rim: 16.5 in
950-16.5 is a numeric bias-ply truck size in which the 950 designation refers to a nominal 9.50-inch section width class and the 16.5 identifies rim diameter. On this GMC C2500 Sierra Grande, that size is tied to the 8600 GVWR configurations and the Bonus Cab front and rear applications shown here. Available choices include STA Traxion and STA Super Transport, both in Blackwall form and both aimed at Military & Truck use. This is the size to evaluate when the truck retains its 16.5-inch heavy-duty bias-ply fitment and the goal is to preserve that traditional construction style.
1980 GMC Trucks C2500 Sierra Grande Sub-Model Tires
Sub-model fitment on the 1980 GMC Trucks C2500 Sierra Grande is not one-size-fits-all. Tire choice changes with GVWR, stud size, and Bonus Cab front or rear application, so identifying the exact configuration matters before selecting a size or deciding between radial and bias-ply construction.
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1980 GMC Trucks C2500 Sierra Grande (7/16 & 1/2 inch studs)(GVWR 6400)
This 6400 GVWR Sierra Grande configuration uses radial tire fitments rather than the 950-16.5 bias-ply setup found on certain heavier-rated versions. The main selection step is confirming which wheel diameter and radial size the truck actually carries before comparing replacement options.
1980 GMC Trucks C2500 Sierra Grande (7/16 & 1/2 inch studs)(GVWR 8600)
This 8600 GVWR Sierra Grande application uses the 950-16.5 bias-ply size on a 16.5-inch rim. Tire selection here centers on staying with the correct heavy-duty bias-ply fitment and comparing the available period-style truck tire series within that size.
1980 GMC Trucks C2500 Sierra Grande (9/16 inch studs)(GVWR 6400)
This 6400 GVWR version with 9/16-inch studs uses radial fitments, not the 950-16.5 bias-ply size tied to certain other configurations. Wheel diameter and exact size code should be confirmed first, especially since both 16-inch and 16.5-inch radial applications appear in this sub-model group.
1980 GMC Trucks C2500 Sierra Grande (9/16 inch studs)(GVWR 8600)
This 8600 GVWR configuration uses 950-16.5 bias-ply tires. That means the buyer should focus on 16.5-inch wheel compatibility, traditional bias-ply construction, and the differences between the available STA truck tire series in this specific size.
1980 GMC Trucks C2500 Sierra Grande Bonus Cab (7/16 & 1/2 inch studs) Front
The front tire fitment for this Bonus Cab application uses 950-16.5 bias-ply construction. Tire choice should stay centered on the correct 16.5-inch heavy-duty size, while also confirming that the wheel and overall setup remain true to the truck's present configuration.
1980 GMC Trucks C2500 Sierra Grande Bonus Cab (7/16 & 1/2 inch studs) Rear
The rear fitment for this Bonus Cab version also uses 950-16.5 bias-ply tires. That keeps selection straightforward in terms of size, but it still helps to compare tire series, rim-width requirements, and the truck's actual wheel condition before putting it back into regular road use.
1980 GMC Trucks C2500 Sierra Grande Bonus Cab (9/16 inch studs) Front
This Bonus Cab front application uses the 950-16.5 bias-ply size. The practical decision is choosing within that heavy-duty truck fitment while confirming the 16.5-inch wheel setup and any changes that may have been made over the truck's service life.
1980 GMC Trucks C2500 Sierra Grande Bonus Cab (9/16 inch studs) Rear
This Bonus Cab rear application also uses 950-16.5 bias-ply tires. Buyers looking at this fitment should keep the focus on proper 16.5-inch compatibility, traditional truck-tire appearance, and the intended use of the vehicle after installation.
The tire sizes listed on this page assume factory-standard vehicle configuration. The following modifications may affect tire fitment and are not reflected in this guide:
Suspension changes (lowering, lift kits, spring replacements)
Body alterations (fender modifications, custom bodywork)
If your vehicle has been modified from factory specifications, verify tire clearance before purchase.
Best 1980 GMC Trucks C2500 Sierra Grande Tires for Sale
Available product choices center on 950-16.5 bias-ply fitment, with STA offerings in the Traxion and Super Transport series. Both are Blackwall Military & Truck tires built for 16.5-inch applications, so comparison comes down to series selection, rim-width compatibility, weight, and intended truck use.
The most common questions for the 1980 GMC Trucks C2500 Sierra Grande center on identifying the correct tire size by sub-model, understanding the mix of 16-inch and 16.5-inch wheels, choosing between available bias-ply products, and checking an older truck carefully before road use.
Tire Size & Fitment
What tire size fits a 1980 GMC Trucks C2500 Sierra Grande?
The 1980 GMC Trucks C2500 Sierra Grande uses four primary tire sizes: 7.50R16, 8.75R16.5, 9.50R16.5, and 950-16.5. The three R-designated sizes are radial applications, while 950-16.5 is a bias-ply size. The correct fitment depends on the exact sub-model, including GVWR, stud configuration, and whether the truck is a standard Sierra Grande or a Bonus Cab front or rear application.
That means the first step is not choosing a brand or sidewall style, but confirming exactly which version of the truck is being serviced and which wheels are actually on it today. A C2500 that has been modified, repowered, or converted over time may no longer carry its original wheel setup, so the size code and wheel diameter should both be verified before tire selection.
What size rim does a 1980 GMC Trucks C2500 Sierra Grande use?
The 1980 GMC Trucks C2500 Sierra Grande uses either a 16-inch or 16.5-inch rim, depending on the tire size and sub-model. The 7.50R16 radial fits a 16-inch wheel, while 8.75R16.5, 9.50R16.5, and 950-16.5 all use 16.5-inch wheels. Because both diameters appear on this truck, the rim size must be confirmed before any tire is ordered or installed.
That distinction matters because a 16-inch tire and a 16.5-inch tire are not interchangeable, even if the size names look similar at a glance. Check the wheel stamping, the existing tire sidewall, and the actual measured wheel setup on the truck. On older pickups, wheel swaps are common, and that can change the correct tire path completely.
Why does the 1980 GMC Trucks C2500 Sierra Grande have more than one tire size?
More than one tire size appears on the 1980 GMC Trucks C2500 Sierra Grande because fitment changes across different GVWR ratings, stud configurations, and Bonus Cab front and rear applications. Some 6400 GVWR versions use radial fitments such as 7.50R16, 8.75R16.5, or 9.50R16.5, while 8600 GVWR and Bonus Cab applications shown here use the 950-16.5 bias-ply size.
The practical takeaway is that the badge alone does not answer the tire question on this truck. Buyers should identify the exact sub-model, confirm the current wheel diameter, and compare the truck's present setup against its intended use. That keeps a work-oriented C2500 from being fitted by assumption rather than by the details that actually control fitment.
Choosing the Right Tire
What should I consider when choosing a 950-16.5 tire for a 1980 GMC Trucks C2500 Sierra Grande?
Start with the basics: 950-16.5 is a 16.5-inch bias-ply truck fitment used on selected 1980 GMC Trucks C2500 Sierra Grande configurations, including 8600 GVWR and Bonus Cab applications shown here. Available choices include STA Traxion and STA Super Transport, both in Blackwall form, both in Military & Truck specification, and both carrying a maximum load capacity of 2780@60 psi.
After confirming the size, compare the details that affect compatibility and use, including the stated 6.50 to 6.75-inch rim-width range, tire weight, and the kind of look or service character you want from the truck. A restoration-minded owner may focus on traditional appearance, while a working truck owner may prioritize the series that best suits intended road use.
What sidewall styles are available for 1980 GMC Trucks C2500 Sierra Grande tires?
The available 950-16.5 tire options for this 1980 GMC Trucks C2500 Sierra Grande fitment are offered in Blackwall form. That suits the truck-focused, heavy-duty character of the size and keeps the appearance traditional rather than decorative. No alternate sidewall treatment appears within the currently available 950-16.5 products tied to this page.
For many square-body GMC truck owners, that simplifies the decision because the real comparison shifts away from sidewall styling and toward tire series, construction, and wheel compatibility. It still helps to think about how the truck will be presented, especially if the goal is a work-truck look, a period-style restoration, or a clean utility-oriented appearance.
What tire series are available for the 1980 GMC Trucks C2500 Sierra Grande?
For the 950-16.5 fitment used on certain 1980 GMC Trucks C2500 Sierra Grande applications, the available tire series are STA Traxion and STA Super Transport. Both are bias-ply Blackwall truck tires intended for 16.5-inch use, and both carry the Military & Truck attribute. That gives buyers a meaningful series choice without changing the underlying tire size.
Series selection matters because two tires in the same size can still differ in character, weight, and intended presentation. Once the truck's fitment has been confirmed, compare the series alongside the stated rim-width range and load specification. That approach helps keep the choice centered on the truck's actual use rather than assuming every 950-16.5 tire serves the same purpose.
Restoration & Appearance
Which tire should I choose for a period-style 1980 GMC Trucks C2500 Sierra Grande?
A period-style choice for a 1980 GMC Trucks C2500 Sierra Grande starts with matching the truck's actual original-type fitment path: radial sizes such as 7.50R16, 8.75R16.5, or 9.50R16.5 on certain 6400 GVWR configurations, or 950-16.5 bias-ply on the 8600 GVWR and Bonus Cab applications shown here. The right tire is the one that matches the truck's exact sub-model and wheel diameter first.
Appearance comes after fitment has been nailed down. On the 950-16.5 side, available Blackwall STA truck tires suit a traditional heavy-duty look. If exact restoration accuracy matters beyond general period style, compare the truck against build records, marque references, and surviving original examples before choosing a tire series or construction based purely on visual preference.
Does correct tire fitment matter for a 1980 GMC Trucks C2500 Sierra Grande restoration?
Correct tire fitment matters a great deal on a 1980 GMC Trucks C2500 Sierra Grande restoration because this truck does not use one universal size across all configurations. GVWR, stud size, and Bonus Cab front or rear application can change the correct tire path, and the difference between 16-inch and 16.5-inch wheels is especially important during a restoration or recommissioning project.
Using the wrong diameter or the wrong construction can change the truck's stance, presentation, and service character in ways that work against a careful build. A restoration-minded owner should confirm the wheel setup already on the truck and decide whether the goal is faithful period style, utility-focused use, or a blend of both before finalizing the tire selection.
Fitment, Maintenance & Road Use
Can modifications affect tire fitment on a 1980 GMC Trucks C2500 Sierra Grande?
Yes, modifications can affect tire fitment on a 1980 GMC Trucks C2500 Sierra Grande. Wheel swaps, suspension changes, brake conversions, ride-height changes, and axle or hub updates can alter the wheel diameter, wheel width, or clearance available for the tire. That is especially important on this truck because both 16-inch and 16.5-inch fitments appear, along with both radial and bias-ply applications.
A truck that looks stock may still have been changed over decades of work and maintenance. Before replacing tires, verify the wheel diameter stamped on the wheel, the width range the tire expects, and the clearance at the fender, suspension, and steering components. That check is more reliable than assuming the current tire size is automatically the correct one.
What should I inspect before driving a 1980 GMC Trucks C2500 Sierra Grande on new tires?
Before driving a 1980 GMC Trucks C2500 Sierra Grande on new tires, inspect the wheels for damage, confirm the wheel diameter and width, and make sure the tires match the truck's actual sub-model fitment. Also check lug hardware, valve stems, brake condition, and whether the tires were mounted to the correct front or rear positions if the application calls for that distinction.
An older heavy-duty pickup should also be checked for steering play, worn suspension parts, uneven ride height, and any signs of fender or inner-wheelhouse interference. Tire pressure should be set appropriately for the tire being used, and the first road test should be short and deliberate. That gives the owner a chance to catch rubbing, vibration, or air-loss issues early.
How should 950-16.5 tires on a collector 1980 GMC Trucks C2500 Sierra Grande be maintained?
950-16.5 tires on a collector 1980 GMC Trucks C2500 Sierra Grande should be kept clean, properly inflated for their intended use, and inspected regularly for cracking, bulges, cuts, irregular wear, and slow air loss. Since the available 950-16.5 products shown here carry a load figure of 2780@60 psi, pressure and load use should be approached with that specification in mind rather than by guesswork.
Collector trucks often sit longer than daily drivers, so tire care includes more than tread depth. Periodic movement helps avoid long-term flat spotting, and storage away from prolonged sunlight, ozone sources, and moisture is worthwhile. It also helps to inspect the wheels and valve stems at the same time, since old wheel hardware can undermine an otherwise sound tire installation.
