The 2008 GMC Trucks Acadia arrived as a full-size crossover built to handle family duty with a more substantial road presence than many midsize utilities of its era. For buyers keeping one on the road today, tire fitment matters because wheel package choice changes the size even when overall tire height stays very close. This Acadia uses radial tires in three primary sizes: 255/65R18, 255/60R19, and 255/55R20. The real decision is confirming which wheel diameter is on the vehicle, especially since the SLT can use more than one size. Once that is settled, the focus shifts to maintaining proper proportions, road manners, and clearance on a stock or modified setup.
Which Tire Size Is Right for The 2008 GMC Trucks Acadia
Three tire sizes apply to the 2008 GMC Trucks Acadia, and the right one depends first on the exact wheel diameter mounted on the vehicle. The key fitment step is confirming whether the Acadia has 18-inch, 19-inch, or 20-inch wheels, since the SLT can use more than one size while the SLE uses 255/65R18. Once wheel diameter is verified, the remaining decision is choosing the right radial tire within that size and checking for any changes from the original wheel setup.
A 255/65R18 tire uses a 255-millimeter nominal section width, a 65-series aspect ratio, radial construction, and an 18-inch rim diameter. On the 2008 GMC Trucks Acadia, this is one of the primary radial fitments and it is the size used on the SLE, while some SLT models also use it. Its overall proportions stay in line with the other Acadia fitments, so the main concern is matching the tire to the correct wheel diameter. This size is a practical choice when the vehicle retains its 18-inch wheel package or has been returned to it.
A 255/55R20 tire keeps the same 255-millimeter nominal width as the other Acadia sizes, but uses a lower 55-series profile on a 20-inch rim. For the 2008 GMC Trucks Acadia, this radial size applies to certain SLT configurations rather than the full model range. Because the sidewall is shorter than the 18-inch and 19-inch fitments, buyers should focus first on confirming that the vehicle actually has 20-inch wheels. It is the appropriate fitment to evaluate when the Acadia carries the larger factory-style wheel package or an equivalent 20-inch setup.
A 255/60R19 tire combines a 255-millimeter nominal section width with a 60-series profile, radial construction, and a 19-inch rim diameter. On the 2008 GMC Trucks Acadia, this size belongs to certain SLT configurations and sits between the 18-inch and 20-inch fitments in wheel diameter. Its overall diameter remains very close to the other primary sizes, which helps preserve the Acadia's intended stance when matched to the correct wheels. This is the size to consider when the vehicle is equipped with 19-inch wheels and the goal is to keep the fitment consistent with that setup.
Sub-model fitment on the 2008 GMC Trucks Acadia is not completely uniform, so trim identification matters before choosing tires. The SLE stays straightforward with one size, while the SLT can use three different radial sizes depending on the wheel package on the vehicle.
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2008 GMC Trucks Acadia SLE
The 2008 GMC Trucks Acadia SLE uses a single primary tire size, 255/65R18 radial, which makes fitment more straightforward than on the SLT. Tire selection still starts with confirming that the vehicle remains on its 18-inch wheels and has not been changed to another Acadia wheel package.
The 2008 GMC Trucks Acadia SLT can use 255/65R18, 255/60R19, or 255/55R20 radial tires, so wheel diameter must be confirmed before selecting a tire. That makes the SLT less about choosing among multiple valid sizes and more about matching the tire to the exact wheel setup currently on the vehicle.
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.
Frequently Asked Questions
Acadia owners usually need to sort out wheel diameter first, then confirm the correct tire size for the exact trim and setup. These FAQs cover size meaning, sub-model differences, radial fitment, tire selection, and the checks that matter before regular road use.
Tire Size & Fitment
What tire size fits a 2008 GMC Trucks Acadia?
The 2008 GMC Trucks Acadia uses three primary tire sizes: 255/65R18, 255/60R19, and 255/55R20. All three are radial sizes, but they do not apply universally across every Acadia configuration because wheel package and sub-model affect which size belongs on the vehicle.
The first step is checking the actual wheel diameter on the Acadia rather than choosing by appearance alone. An SLE uses 255/65R18, while an SLT can use 18-inch, 19-inch, or 20-inch fitments. If the vehicle has changed wheels at some point, confirm the wheel size on the vehicle before selecting replacement tires.
What size rim does a 2008 GMC Trucks Acadia use?
A 2008 GMC Trucks Acadia can use 18-inch, 19-inch, or 20-inch rims, depending on the exact trim and wheel package. Those rim diameters correspond to the three primary tire sizes: 255/65R18, 255/60R19, and 255/55R20.
Rim diameter is the most important fitment checkpoint on this Acadia because each tire size is built for a different wheel. The SLE uses an 18-inch fitment, while the SLT can appear with all three diameters. A quick wheel check prevents buying the right overall tire profile in the wrong rim size.
Do all 2008 GMC Trucks Acadia sub-models use the same tire size?
No, all 2008 GMC Trucks Acadia sub-models do not use the same tire size. The SLE uses 255/65R18, while the SLT can use 255/65R18, 255/60R19, or 255/55R20 depending on the wheel setup.
That difference matters because the Acadia's overall tire height remains close across the three sizes, so a quick visual estimate can be misleading. Trim level helps narrow the fitment, but the wheel actually on the vehicle is what needs to be confirmed. Checking the sidewall on the current tire and measuring the rim diameter is the safest next step.
Choosing the Right Tire
What should I consider when choosing a 255/65R18 tire for a 2008 GMC Trucks Acadia?
Start by confirming that 255/65R18 is the correct size for the specific 2008 GMC Trucks Acadia and not one of the 19-inch or 20-inch fitments used on some SLT models. This size is the primary 18-inch radial fitment and is the straightforward choice for the SLE.
After size confirmation, focus on matching the tire to how the Acadia is used, whether that means regular family driving, seasonal use, or an older vehicle that sees lighter mileage. Wheel condition, suspension wear, and alignment are worth checking at the same time, since uneven wear or handling complaints are not always caused by the tire itself.
What should I consider when choosing a 255/60R19 tire for a 2008 GMC Trucks Acadia?
A 255/60R19 tire is correct for certain 2008 GMC Trucks Acadia SLT configurations, so the key consideration is confirming that the vehicle actually has 19-inch wheels. It shares the same nominal section width as the other Acadia sizes, but it is built specifically for a 19-inch rim.
Once wheel size is verified, look at the tire as part of the complete setup rather than as an isolated number. Tire age, wear pattern, and the condition of the remaining tires matter if only one or two are being replaced. Clearance should also be checked if the Acadia has aftermarket wheels or any suspension changes.
How do I choose between the available tire sizes for a 2008 GMC Trucks Acadia?
The correct choice is not made by preference alone, because the 2008 GMC Trucks Acadia's three tire sizes are tied to different wheel diameters. A 255/65R18 belongs on an 18-inch rim, a 255/60R19 on a 19-inch rim, and a 255/55R20 on a 20-inch rim.
The practical way to decide is to identify the wheel package currently on the vehicle and stay with the corresponding tire size unless the entire wheel-and-tire setup is being changed intentionally. When the Acadia has replacement wheels, verify diameter and clearance at the vehicle before assuming the trim alone tells the whole story.
Restoration & Appearance
Does correct tire fitment matter for a 2008 GMC Trucks Acadia restoration?
Yes, correct tire fitment still matters on a 2008 GMC Trucks Acadia restoration or preservation project, even though it is a modern crossover rather than an earlier collector car. The right 18-inch, 19-inch, or 20-inch tire size helps preserve the intended stance, wheel proportion, and everyday drivability of the vehicle.
Appearance on this Acadia is tied more to keeping the proper wheel-and-tire relationship than to vintage sidewall styling. Matching the tire to the correct rim diameter is the first step, and checking that the vehicle has not been altered with a different wheel package is just as important when trying to return it to a more original-looking presentation.
Which tire should I choose for a period-style 2008 GMC Trucks Acadia?
A period-style approach for a 2008 GMC Trucks Acadia starts with using the tire size that matches the wheel package the vehicle was built around, whether that is 255/65R18, 255/60R19, or 255/55R20. Since all three primary fitments are radial, the main concern is preserving the right overall look for the trim and wheel diameter.
The visual character of this Acadia comes more from proper scale than from specialty sidewall treatments. A tire that matches the correct rim diameter and maintains the stock-style proportions will usually look more appropriate than an off-size substitute. Checking current wheels first helps avoid a mismatch between trim expectation and the setup actually on the vehicle.
Fitment, Maintenance & Road Use
Can modifications affect tire fitment on a 2008 GMC Trucks Acadia?
Yes, modifications can affect tire fitment on a 2008 GMC Trucks Acadia. Wheel changes, altered offset, suspension lowering, worn springs, or body modifications can all change how a 255/65R18, 255/60R19, or 255/55R20 tire sits in the wheel opening and how much clearance remains during steering and suspension movement.
An Acadia that has aftermarket wheels should be checked at the vehicle rather than judged by trim level alone. Tire size, wheel diameter, and clearance need to work together, especially near the strut, fender edge, and inner wheelhouse. A setup that looks close on paper may still need careful verification before regular driving.
What should I inspect before driving a 2008 GMC Trucks Acadia on new tires?
Before driving a 2008 GMC Trucks Acadia on new tires, confirm that the tire size matches the wheel diameter and that all tires are inflated properly for the intended load and use. It also makes sense to inspect wheel condition, valve stems, and the mounting balance so the new tires start from a sound baseline.
A road-ready check should also include alignment, brake condition, and any signs of suspension wear that could cause irregular wear or poor tracking. After installation, look for rubbing at full steering lock and over bumps, especially if the Acadia has different wheels than it originally used. Catching those issues early helps protect the new tires.
How often should tires on a 2008 GMC Trucks Acadia be inspected?
Tires on a 2008 GMC Trucks Acadia should be inspected regularly, not only when tread looks low. A routine visual check for uneven wear, cracking, cuts, bulges, and air loss is especially helpful on older vehicles that may spend long periods parked or cover fewer miles than they once did.
Monthly pressure checks are a sensible baseline, and any vibration, pull, or sudden change in ride quality should prompt a closer inspection right away. The Acadia's correct tire size also matters during those checks, since replacing one tire or rotating in a mismatched size can create fitment and handling issues even when the tread still appears usable.
