The 2018 GMC Trucks Sierra 2500 HD sits in the heavy-duty pickup world where towing, payload, and everyday road use all place real demands on tire choice. Buyers looking at this exact truck are usually balancing work-truck function, trim-level appearance, and the wheel package already on the vehicle. Tire fitment on the 2018 GMC Trucks Sierra 2500 HD is radial throughout, but it is not limited to one size, with 245/75R17, 265/70R18, and 265/60R20 all in the mix depending on sub-model and wheel setup. That makes wheel diameter the first thing to confirm before comparing tires. From there, the decision becomes matching the truck's trim and intended use to the right size and tire style.
Which Tire Size Is Right for The 2018 GMC Trucks Sierra 2500 HD
The 2018 GMC Trucks Sierra 2500 HD uses three primary tire sizes, and they are tied to different wheel diameters and sub-model combinations. Before choosing a tire, confirm whether the truck is on 17-inch, 18-inch, or 20-inch wheels, then verify the exact sub-model and any wheel changes made over time. Once that is settled, the real comparison is between the correct size for the truck's setup and the tire options available within that size.
245/75R17 is a metric radial size in which 245 is the nominal section width in millimeters, 75 is the aspect ratio, R identifies radial construction, and 17 is the wheel diameter in inches. On the 2018 GMC Trucks Sierra 2500 HD, this size is part of the truck's primary radial fitment range and is used on certain sub-model and wheel combinations. Available product coverage in this size includes a BFGoodrich All-Terrain T/A KO2 with raised white letter sidewalls. This size is worth close attention if the truck has 17-inch wheels and is being set up for a more utility-focused or all-terrain style of use.
265/70R18 is a metric radial size where 265 indicates nominal section width in millimeters, 70 is the aspect ratio, R denotes radial construction, and 18 identifies the wheel diameter in inches. This size appears across multiple 2018 GMC Trucks Sierra 2500 HD sub-models, making it one of the more broadly used fitments within the range. Its role is tied to 18-inch wheel setups, so it should not be selected simply because it appears on another trim level. It is the right size to evaluate when the truck already has 18-inch wheels and the goal is to stay with its proper overall fitment pattern.
265/60R20 is a metric radial size with a 265-millimeter nominal section width, a 60-series aspect ratio, radial construction, and a 20-inch wheel diameter. On the 2018 GMC Trucks Sierra 2500 HD, this size belongs to specific trim and wheel combinations rather than every version of the truck. Compared with the other primary sizes here, its lower profile is part of a 20-inch wheel package, so correct wheel confirmation matters before any purchase decision. This is the size to review when the truck carries factory-style or replacement 20-inch wheels and appearance is part of the selection process.
Sub-model fitment on the 2018 GMC Trucks Sierra 2500 HD is not one-size-fits-all, because Base, Denali, SLE, and SLT trucks can use different tire and wheel combinations. Checking the exact sub-model matters, but confirming the wheel diameter already on the truck is just as important before selecting a tire.
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2018 GMC Trucks Sierra 2500 HD Base
The 2018 GMC Trucks Sierra 2500 HD Base uses 245/75R17 or 265/70R18 radial fitments, depending on the wheel setup. Tire selection starts with confirming whether the truck is on 17-inch or 18-inch wheels, then choosing a tire that matches how the truck is actually used.
The 2018 GMC Trucks Sierra 2500 HD Denali uses either 265/60R20 or 265/70R18 radial tires. That means the decision is centered on confirming whether the truck has its 20-inch or 18-inch wheel package before comparing tire style, profile, and intended road use.
The 2018 GMC Trucks Sierra 2500 HD SLE has the broadest fitment spread here, with 245/75R17, 265/70R18, and 265/60R20 all applying to different wheel combinations. Buyers should verify the actual wheels on the truck first, especially if it has been upgraded or changed since new.
The 2018 GMC Trucks Sierra 2500 HD SLT uses 265/60R20 or 265/70R18 radial tires depending on wheel package. That makes wheel diameter the key checkpoint, followed by selecting a tire that suits the truck's current appearance goals and working demands.
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 2018 GMC Trucks Sierra 2500 HD Tires for Sale
Current product coverage for the 2018 GMC Trucks Sierra 2500 HD includes a BFGoodrich All-Terrain T/A KO2 in 245/75R17. That option uses radial construction, raised white letter sidewalls, and a 17-inch rim-width range that is useful to compare against the truck's actual wheel setup.
These FAQs focus on the tire sizes used on the 2018 GMC Trucks Sierra 2500 HD, how sub-model and wheel packages affect fitment, and what to check when comparing tires for work use, appearance, and road readiness.
Tire Size & Fitment
What tire size fits a 2018 GMC Trucks Sierra 2500 HD?
The 2018 GMC Trucks Sierra 2500 HD uses three primary radial tire sizes: 245/75R17, 265/70R18, and 265/60R20. The correct one depends on the truck's sub-model and, just as importantly, the wheel diameter currently on the truck.
A Base truck may use 17-inch or 18-inch fitment, while Denali, SLE, and SLT trucks can also bring 20-inch wheels into the picture. The safest starting point is to confirm the exact sub-model, then verify the actual wheel size on the truck before comparing any tire options.
What size rim does a 2018 GMC Trucks Sierra 2500 HD use?
A 2018 GMC Trucks Sierra 2500 HD may use 17-inch, 18-inch, or 20-inch rims, depending on sub-model and wheel package. Those rim diameters correspond to the truck's primary tire sizes of 245/75R17, 265/70R18, and 265/60R20.
Rim diameter is the first fitment detail to verify because the tire size must match it exactly. A truck that has had aftermarket wheels installed or a factory wheel package swapped over time may no longer match the trim-level expectation, so checking the wheel itself is more reliable than assuming by model name alone.
Do all 2018 GMC Trucks Sierra 2500 HD sub-models use the same tire size?
No, the 2018 GMC Trucks Sierra 2500 HD sub-models do not all use the same tire size. Base, Denali, SLE, and SLT trucks share some overlap, but the full fitment range includes 245/75R17, 265/70R18, and 265/60R20.
That variation means trim name alone is not always enough to select a tire. The best approach is to identify the sub-model, then confirm whether the truck is on 17-inch, 18-inch, or 20-inch wheels before comparing tires, especially if the truck has seen wheel upgrades or replacement wheels during its life.
Choosing the Right Tire
What should I consider when choosing a tire for a 2018 GMC Trucks Sierra 2500 HD?
Start with the correct primary size for the truck, because the 2018 GMC Trucks Sierra 2500 HD can use 245/75R17, 265/70R18, or 265/60R20. The right choice depends on the sub-model, the wheel diameter on the truck, and whether the goal is work use, highway use, or a more aggressive tread style.
After size is confirmed, compare construction details and any product-specific factors that matter for the truck's use. On available 245/75R17 coverage, for example, rim-width compatibility, load capacity, weight, and sidewall style all shape the decision more than trim name alone.
What sidewall styles are available for 2018 GMC Trucks Sierra 2500 HD tires?
Among the currently available products for this fitment, 245/75R17 is offered with an RWL sidewall, which is a raised white letter presentation. That gives the truck a more traditional all-terrain look than a plain black sidewall.
Sidewall treatment affects appearance first, but it should still be considered only after confirming the correct tire size and wheel diameter. A Sierra 2500 HD used for work may call for one visual style, while a truck built around a specific wheel-and-tire look may point toward a different presentation within the proper size.
What brands offer tires for the 2018 GMC Trucks Sierra 2500 HD?
Current product coverage for the 2018 GMC Trucks Sierra 2500 HD includes BFGoodrich in 245/75R17. The available tire in that size is the All-Terrain T/A KO2, a radial all-terrain design.
Brand is only one part of the decision, especially on a truck with several possible wheel packages. Once the exact size is confirmed, compare the tire's intended use, load figure, rim-width range, and sidewall style so the choice matches both the truck's fitment and the way it will be driven.
Fitment, Maintenance & Road Use
Can modifications affect tire fitment on a 2018 GMC Trucks Sierra 2500 HD?
Yes, modifications can affect tire fitment on a 2018 GMC Trucks Sierra 2500 HD. Aftermarket wheels, suspension changes, leveling kits, lowering, and even body or fender alterations can change the clearance and wheel specifications that the original tire sizes were designed around.
A truck may still use one of the correct primary sizes on paper, but wheel width, offset, and available clearance can shift the result in practice. Any Sierra 2500 HD with non-stock wheels or suspension should be checked carefully at full steering lock and under load before settling on a replacement tire.
What should I inspect before driving a 2018 GMC Trucks Sierra 2500 HD on new tires?
Before driving a 2018 GMC Trucks Sierra 2500 HD on new tires, inspect wheel condition, confirm the tire size matches the rim diameter, and make sure inflation is set appropriately for the tire and the truck's use. It is also smart to look over valve stems, lug torque, and basic tread and sidewall condition.
A heavy-duty pickup places real demand on its tires, so a quick visual check is not enough if the truck has been parked for a long time or recently modified. Clearance at the fenders and suspension, even wear across the tread, and stable air pressure are all worth verifying before regular road use.
How often should tires on a 2018 GMC Trucks Sierra 2500 HD be inspected?
Tires on a 2018 GMC Trucks Sierra 2500 HD should be inspected regularly, not just at replacement time. A practical routine is to check pressure and visible condition often, and to give the tires a closer inspection before towing, hauling, or taking the truck on a longer drive.
Inspection should include tread wear, cracking, bulges, cuts, and signs of slow air loss. Trucks that see seasonal use or long periods of sitting deserve extra attention, because age and storage conditions can matter just as much as mileage on a heavy-duty pickup that is expected to work when needed.
