The 2008 GMC Trucks Sierra 1500 sits in the era when full-size pickups had to balance everyday comfort, work capability, and increasingly upscale trim choices. That matters for tire fitment because this Sierra 1500 uses several different radial sizes depending on sub-model, package, and wheel setup, including 17-inch, 18-inch, and 20-inch applications. Some versions stay with practical 245/70R17 or 265/70R17 sizing, while others move to 265/65R18 or 275/55R20 for a different wheel-and-tire presentation. The right choice starts with confirming the exact sub-model and wheel diameter, then comparing the available tire specifications against how the truck is actually equipped and used.
Which Tire Size Is Right for The 2008 GMC Trucks Sierra 1500
The 2008 GMC Trucks Sierra 1500 uses four primary tire sizes, and the right one depends on the exact sub-model and wheel package. Fitment varies across 17-inch, 18-inch, and 20-inch rims, so the first step is confirming the truck's actual wheel diameter before narrowing down size, load capability, and the product choices available for that setup.
Fit(s): Denali, SLE w/Z71 Pkg., and SLT w/Z71 Pkg.
Construction: Radial|Rim: 18 in
A 265/65R18 tire is a metric radial size with a 265-millimeter section width, a 65-series profile, and fitment for an 18-inch rim. On the 2008 GMC Trucks Sierra 1500, this size is part of the truck's modern radial fitment range and appears on specific trims and package combinations rather than across the whole model line. It represents a middle ground between the taller-sidewall 17-inch fitments and the lower-profile 20-inch setup. This size is the one to evaluate when the truck is already equipped with 18-inch wheels and the goal is to keep the intended wheel diameter and overall tire character in place.
Fit(s): Denali, SLE (20 Inch Option), SLE w/Max Trailer Pkg., SLT (20 Inch Option), and SLT w/Max Trailer Pkg.
Construction: Radial|Rim: 20 in
A 275/55R20 tire uses a 275-millimeter section width, a 55-series profile, and mounts on a 20-inch rim. For the 2008 GMC Trucks Sierra 1500, this size belongs to certain Denali, SLE, and SLT configurations that use the larger wheel package. Its lower profile compared with the 17-inch and 18-inch sizes gives the truck a distinct wheel-and-tire presentation tied to that setup. This is the correct size to consider only after confirming that the truck actually has the 20-inch wheel application, since rim diameter is the first fitment checkpoint here.
A 245/70R17 tire is a metric radial with a 245-millimeter section width, a 70-series aspect ratio, and a 17-inch rim diameter. On the 2008 GMC Trucks Sierra 1500, it appears on several 4x2 and some 4x4 configurations, making it one of the core 17-inch fitments in the range. BFGoodrich offers this size in the All-Terrain T/A KO2 series with a raised white letter sidewall, adding a more truck-oriented appearance to the size. It is the size to compare when the truck uses a 17-inch wheel and the priority is keeping the intended diameter while reviewing load and rim-width specifications carefully.
A 265/70R17 tire carries a 265-millimeter section width, a 70-series profile, and fits a 17-inch rim. Within the 2008 GMC Trucks Sierra 1500 lineup, this size is used across several 4x4, package-equipped, and towing-related configurations, so it is a common fitment but not universal to every truck. BFGoodrich offers it in the All-Terrain T/A KO2 series with raised white letter styling, and the available products differ in load specification within the same size. This size deserves a close look when the truck has 17-inch wheels and the buyer needs to match both the fitment and the intended duty level.
Sub-model fitment on the 2008 GMC Trucks Sierra 1500 is not one-size-fits-all. Trim level, drivetrain, and package choices can change both tire size and wheel diameter, so confirming the exact sub-model is the key step before comparing tires.
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2008 GMC Trucks Sierra 1500 Denali
The 2008 GMC Trucks Sierra 1500 Denali uses either 265/65R18 or 275/55R20 radial tires, depending on its wheel setup. Tire selection starts with confirming whether the truck is on 18-inch or 20-inch wheels, then matching the replacement tire to that configuration.
The 2008 GMC Trucks Sierra 1500 SL 4x2 uses a 245/70R17 radial tire. That keeps selection straightforward, with the main follow-up being wheel-width and load-spec review within the correct 17-inch fitment.
The 2008 GMC Trucks Sierra 1500 SL 4x4 uses a 265/70R17 radial tire. Tire shopping for this sub-model is less about choosing between sizes and more about confirming the truck's 17-inch wheel setup and intended use.
The 2008 GMC Trucks Sierra 1500 SLE (20 Inch Option) uses a 275/55R20 radial tire. The important point here is staying with the 20-inch wheel application and checking overall compatibility before moving to any alternate tire specification.
The 2008 GMC Trucks Sierra 1500 SLE 4x2 can use either 245/70R17 or 265/70R17 radial tires. Choosing correctly means verifying which wheel-and-tire setup is actually on the truck rather than assuming one 17-inch size fits every SLE 4x2.
The 2008 GMC Trucks Sierra 1500 SLE 4x4 can use 245/70R17 or 265/70R17 radial tires. Because both are 17-inch fitments, the buyer needs to confirm the current wheel and tire setup carefully before selecting a replacement.
2008 GMC Trucks Sierra 1500 SLE w/Max Trailer Pkg.
The 2008 GMC Trucks Sierra 1500 SLE w/Max Trailer Pkg. uses either 265/70R17 or 275/55R20 radial tires. Tire choice depends first on whether the truck carries the 17-inch or 20-inch wheel setup, then on matching the tire's intended load role.
The 2008 GMC Trucks Sierra 1500 SLE w/Z71 Pkg. can be fitted with 265/65R18 or 265/70R17 radial tires. That makes wheel diameter the first item to verify, followed by choosing the tire that matches the truck's existing package and stance.
The 2008 GMC Trucks Sierra 1500 SLT (20 Inch Option) uses a 275/55R20 radial tire. Tire selection is centered on the truck's 20-inch wheel package, so maintaining the proper size and checking clearance remain the practical priorities.
The 2008 GMC Trucks Sierra 1500 SLT 4x2 can use either 245/70R17 or 265/70R17 radial tires. Both are 17-inch sizes, so the deciding factor is the truck's actual wheel-and-tire configuration rather than trim name alone.
The 2008 GMC Trucks Sierra 1500 SLT 4x4 can use 245/70R17 or 265/70R17 radial tires. A careful check of the current setup is important here, since the correct replacement depends on which 17-inch size the truck already uses.
2008 GMC Trucks Sierra 1500 SLT w/Max Trailer Pkg.
The 2008 GMC Trucks Sierra 1500 SLT w/Max Trailer Pkg. uses either 265/70R17 or 275/55R20 radial tires. The right replacement starts with confirming wheel diameter, then comparing tire specifications that suit the truck's actual working setup.
The 2008 GMC Trucks Sierra 1500 SLT w/Z71 Pkg. can use 265/65R18 or 265/70R17 radial tires. Since this sub-model spans two wheel diameters, the practical first step is checking the wheels before narrowing down tire options.
The 2008 GMC Trucks Sierra 1500 WT 4x2 uses a 245/70R17 radial tire. That makes the main decision a matter of choosing the right 17-inch tire specification for the truck's use rather than sorting through multiple primary sizes.
The 2008 GMC Trucks Sierra 1500 WT 4x4 can use either 245/70R17 or 265/70R17 radial tires. Because both sizes fit 17-inch rims, confirming the truck's present tire size is essential before making a replacement choice.
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 2008 GMC Trucks Sierra 1500 Tires for Sale
Available product choices for the 2008 GMC Trucks Sierra 1500 center on the 17-inch sizes, with BFGoodrich All-Terrain T/A KO2 options in 245/70R17 and 265/70R17. These tires use radial construction, raised white letter sidewalls, and different load specifications within the same fitment range.
Owners of a 2008 GMC Trucks Sierra 1500 usually need to sort out sub-model fitment first, then compare wheel diameter, tire size, and available radial choices. These FAQs focus on size selection, 17-inch product differences, and practical checks before road use.
Tire Size & Fitment
What tire size fits a 2008 GMC Trucks Sierra 1500?
The 2008 GMC Trucks Sierra 1500 uses four primary radial tire sizes: 245/70R17, 265/70R17, 265/65R18, and 275/55R20. The correct size depends on the exact sub-model, drivetrain, package, and wheel setup rather than the Sierra 1500 name alone.
The practical next step is to confirm the truck's actual wheels before choosing a tire. A 17-inch Sierra may use either 245/70R17 or 265/70R17, while some trims and package combinations use 18-inch or 20-inch rims, so reading the current tire size and verifying wheel diameter prevents an avoidable mismatch.
What size rim does a 2008 GMC Trucks Sierra 1500 use?
A 2008 GMC Trucks Sierra 1500 can use 17-inch, 18-inch, or 20-inch rims depending on sub-model and package. The 245/70R17 and 265/70R17 sizes use 17-inch rims, 265/65R18 uses an 18-inch rim, and 275/55R20 uses a 20-inch rim.
Rim diameter is the first fitment detail to verify because the tire must match the wheel exactly. Once that is confirmed, the buyer can narrow the choice to the correct size for that wheel and then compare details such as rim-width suitability, load specification, and the truck's intended use.
Why does the 2008 GMC Trucks Sierra 1500 have more than one tire size?
The Sierra 1500 uses more than one tire size because the lineup includes different trims, drivetrains, and package combinations. Some versions use 17-inch wheels, others use 18-inch wheels, and certain configurations use 20-inch wheels, which changes the tire size that belongs on the truck.
That means tire selection should start with the exact sub-model and the actual wheels on the vehicle, not with a broad year-make-model lookup alone. A Denali, a WT 4x2, and an SLE with a package option may all fall under the same model name while requiring different tire dimensions.
Choosing the Right Tire
What should I consider when choosing a 265/70R17 tire for a 2008 GMC Trucks Sierra 1500?
Start with the basics: confirm that 265/70R17 is the size already used on the truck and that the wheel is a 17-inch wheel within the tire's rim-width range. In this size, BFGoodrich All-Terrain T/A KO2 options are available with different load specifications, so the size alone does not tell the whole story.
The useful comparison points are rim-width compatibility, maximum load rating at its stated pressure, and how the truck will actually be used. A Sierra driven lightly and a Sierra asked to carry or tow more weight may need different product specifications even though both wear the same 265/70R17 size.
What sidewall styles are available for 2008 GMC Trucks Sierra 1500 tires?
Among the available products for this Sierra 1500 fitment range, the visible sidewall style is RWL, or raised white letter. That sidewall treatment appears on the BFGoodrich All-Terrain T/A KO2 options offered in the supported 17-inch sizes.
Sidewall style is partly an appearance choice and partly a clue to the overall character of the tire. Raised white letter tires give the truck a more traditional light-truck presentation, but the first priority should still be matching the correct size, wheel diameter, and load specification for the exact Sierra setup.
What brands offer tires for the 2008 GMC Trucks Sierra 1500?
The available products for the covered Sierra 1500 tire sizes include BFGoodrich. In the current 17-inch fitments, the brand represented is the BFGoodrich All-Terrain T/A KO2 series in both 245/70R17 and 265/70R17 applications.
Brand is only one part of the decision. Once the correct size is confirmed, compare the tire's series, sidewall presentation, rim-width range, and load specification to make sure the product suits the truck's actual job, whether that means general road use, a more aggressive look, or heavier-duty service.
Restoration & Appearance
Which tire should I choose for a period-style 2008 GMC Trucks Sierra 1500?
A period-style choice for a 2008 GMC Trucks Sierra 1500 usually begins with keeping the truck's original wheel diameter and primary tire size intact. For trucks using the covered 17-inch fitments, the BFGoodrich All-Terrain T/A KO2 with raised white letters delivers a look that suits a truck-focused presentation from that era.
Appearance should still come after fitment. Matching the existing 17-inch, 18-inch, or 20-inch setup keeps the overall look in scale with the truck, while changing wheel diameter or tire profile can shift the visual character noticeably. Buyers focused on strict originality should also compare against vehicle-specific documentation and trim details.
How does tire construction affect the appearance of a restored 2008 GMC Trucks Sierra 1500?
On a 2008 GMC Trucks Sierra 1500, the primary fitments are radial tires, so the construction itself does not create a bias-ply-versus-radial appearance choice. The visible difference comes more from size, sidewall styling, and the wheel diameter tied to the truck's exact trim or package.
That makes the appearance decision more about preserving the truck's intended stance and presentation than about changing tire construction. A 17-inch all-terrain tire with raised white letters gives a different visual result than a 20-inch application, even though both are proper radial formats for this model range.
Fitment, Maintenance & Road Use
Can modifications affect tire fitment on a 2008 GMC Trucks Sierra 1500?
Yes, modifications can affect tire fitment on a 2008 GMC Trucks Sierra 1500. Aftermarket wheels, suspension lifts or drops, steering changes, and body alterations can change the clearance and wheel dimensions that the original tire size was intended to work with.
A truck that has been modified should be checked more carefully than one on its original setup. Wheel diameter is only the beginning; wheel width, offset, fender clearance, and steering clearance all matter when replacing tires, especially on a Sierra that already had multiple factory size and wheel combinations.
What should I inspect before driving a 2008 GMC Trucks Sierra 1500 on new tires?
Before driving a 2008 GMC Trucks Sierra 1500 on new tires, inspect wheel condition, verify the tires are the correct size for the truck's setup, and confirm inflation matches the tire's requirements and the vehicle's intended use. It also helps to check for any obvious clearance issues at full steering lock.
Roadworthiness depends on more than fresh tread. A quick inspection of suspension condition, lug hardware, air retention, and any signs of rubbing can prevent trouble once the truck is back in service. On a pickup with multiple possible fitments, rechecking the wheel diameter and size code is especially worthwhile.
How often should tires on a 2008 GMC Trucks Sierra 1500 be inspected?
Tires on a 2008 GMC Trucks Sierra 1500 should be inspected regularly, not just when replacement time arrives. Pressure, tread wear, cuts, bulges, cracking, and uneven wear patterns are all worth checking often, especially on a truck that sees mixed road, work, or occasional-use duty.
Frequent inspection helps catch problems that a size chart cannot reveal, such as alignment wear or contact issues from wheel changes. A Sierra that tows, hauls, or spends time parked between uses benefits from more consistent checks, since load demands and inactivity can both affect tire condition over time.
