The 2008 Pontiac G8 arrived as Pontiac’s rear-wheel-drive performance sedan, blending modern V8-era muscle-car attitude with full-size four-door practicality. It occupies a distinctive place in late Pontiac history, especially for owners who want a contemporary driver with strong enthusiast appeal. Tire fitment centers on two primary radial sizes, 245/45R18 and 245/40R19, with the correct choice depending on the exact G8 configuration. Available options focus on modern blackwall performance tires from BFGoodrich and Nitto across several g-Force and NT555 series choices. For most buyers, the key is confirming whether the car carries 18-inch or 19-inch wheels and then selecting the tire that suits road use, appearance, and wheel setup.
Which Tire Size Is Right for The 2008 Pontiac G8
The 2008 Pontiac G8 uses two primary tire sizes, and the correct one depends on the exact sub-model and wheel package. Both fitments are radial designs, but they do not share the same rim diameter, so the first step is confirming whether the car has 18-inch or 19-inch wheels. Once that is settled, the decision shifts to tire series, load and rim-width compatibility, and whether the car is set up for summer-oriented or all-season use.
A 245/45R18 tire uses a 245-millimeter section width, a 45-series aspect ratio, radial construction, and an 18-inch rim diameter. On the 2008 Pontiac G8, this is a modern radial fitment used across several configurations, including Base and multiple GT applications. In this size, available choices include BFGoodrich and Nitto blackwall performance tires across series such as g-Force Comp 2 AS, g-Force Sport Comp 2, g-Force Phenom T/A, and NT555 G2. This size is the right place to focus if your G8 carries the 18-inch wheel setup and you want to compare tire character within the correct fitment.
A 245/40R19 tire keeps the same 245-millimeter nominal width but pairs it with a lower 40-series profile on a 19-inch rim. For the 2008 Pontiac G8, this radial size is tied to the GT w/Sport Pkg. (Summer Only) configuration rather than the broader 18-inch-wheel group. Available options in this size center on BFGoodrich blackwall performance tires, including g-Force Comp 2 AS, g-Force Sport Comp 2, and g-Force Phenom T/A. This fitment should be evaluated by owners who have confirmed the 19-inch sport-package wheel diameter and want to stay aligned with that setup.
Sub-model fitment matters on the 2008 Pontiac G8 because tire size changes with the wheel and package combination. Most covered versions use the 18-inch setup, while the GT w/Sport Pkg. (Summer Only) moves to a 19-inch fitment, so identifying the exact sub-model is the first step before comparing tires.
1
2008 Pontiac G8 (Summer Only)
The 2008 Pontiac G8 (Summer Only) uses the 245/45R18 radial tire size. That keeps the decision focused on choosing among available 18-inch blackwall performance tires and confirming that the wheels on the car still match the original 18-inch fitment.
The 2008 Pontiac G8 Base uses the 245/45R18 radial size on an 18-inch wheel. Buyers can concentrate on comparing tire series and specifications within that fitment rather than sorting through multiple primary sizes, while still checking for any later wheel changes.
The 2008 Pontiac G8 GT (All-Season Tire) uses the 245/45R18 radial size. Tire selection here starts with the 18-inch fitment, then moves to choosing the product that best matches how the car is driven and whether a more road-oriented or sport-oriented tire character is preferred.
The 2008 Pontiac G8 GT (Summer Only) also uses the 245/45R18 radial fitment. That means wheel confirmation remains important, but most owners of this configuration will be comparing available 18-inch performance tires rather than deciding between different primary sizes.
The 2008 Pontiac G8 GT w/Sport Pkg. (Summer Only) uses the 245/40R19 radial size rather than the 18-inch fitment found on the other covered G8 versions. This makes wheel diameter the critical check before purchase, followed by comparison of the available 19-inch BFGoodrich performance tire options.
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 Pontiac G8 Tires for Sale
Available 2008 Pontiac G8 tires center on 245/45R18 and 245/40R19 radial blackwall performance fitments from BFGoodrich and Nitto. The product grid lets you compare g-Force and NT555 series choices, along with rim-width compatibility, load figures where stated, and other specification differences within the correct wheel diameter.
Common 2008 Pontiac G8 tire questions usually come down to confirming the correct size for the exact sub-model, understanding the 18-inch versus 19-inch fitments, and comparing available radial performance tire choices before the car goes back on the road.
Tire Size & Fitment
What tire size fits a 2008 Pontiac G8?
The 2008 Pontiac G8 uses either 245/45R18 or 245/40R19, depending on the specific sub-model and wheel package. Base, Summer Only, GT (All-Season Tire), and GT (Summer Only) applications use 245/45R18, while the GT w/Sport Pkg. (Summer Only) uses 245/40R19.
The practical difference is not just the tire size itself but the wheel diameter behind it. A buyer should confirm whether the car has 18-inch or 19-inch wheels before choosing a tire, especially on used G8s that may have been changed from stock-style wheel setups over time.
What size rim does a 2008 Pontiac G8 use?
A 2008 Pontiac G8 uses either an 18-inch or 19-inch rim, depending on the tire size and sub-model. The 245/45R18 fitment uses an 18-inch rim, while the 245/40R19 fitment uses a 19-inch rim tied to the GT w/Sport Pkg. (Summer Only) configuration.
Checking rim diameter is the first fitment step because a tire for an 18-inch wheel cannot be mounted on a 19-inch wheel, and the reverse is also true. It also helps to confirm wheel width before comparing products, since the available tires carry defined rim-width compatibility ranges.
Do all 2008 Pontiac G8 sub-models use the same tire size?
No, not all 2008 Pontiac G8 sub-models use the same tire size. Most covered versions use 245/45R18, but the 2008 Pontiac G8 GT w/Sport Pkg. (Summer Only) uses 245/40R19 instead, so there is a genuine fitment split within the model line.
That means identifying the exact sub-model matters before comparing brands or tire series. It is also worth looking at the actual wheels on the car, since package changes, later owner modifications, or take-off wheels can leave a G8 wearing a different setup than its original configuration.
Choosing the Right Tire
What should I consider when choosing a 245/45R18 tire for a 2008 Pontiac G8?
Choosing a 245/45R18 tire for a 2008 Pontiac G8 starts with confirming that the car is one of the 18-inch-wheel applications. In this size, available options include BFGoodrich and Nitto radial blackwall tires across several performance-oriented series, with rim-width compatibility commonly centered around 7.5 to 9.0 inches.
After confirming fitment, the real comparison is between tire series, load specifications where stated, and the kind of road use the car sees. A regularly driven G8 may call for a different balance than a fair-weather performance sedan, so wheel width, intended use, and overall setup should guide the final choice.
What brands offer tires for the 2008 Pontiac G8?
Tires for the 2008 Pontiac G8 are available from BFGoodrich and Nitto in the covered fitments. BFGoodrich appears in both 245/45R18 and 245/40R19, while Nitto is available in the 245/45R18 size through the NT555 G2 line.
Brand choice should still come after confirming the correct size and wheel diameter for the car. Once that is settled, comparing the tire series within each brand is more useful than choosing by name alone, since the product lines differ in construction details, rim-width ranges, and intended driving character.
What tire series are available for the 2008 Pontiac G8?
The available 2008 Pontiac G8 tire series include BFGoodrich g-Force Comp 2 AS, BFGoodrich g-Force Sport Comp 2, BFGoodrich g-Force Phenom T/A, and Nitto NT555 G2. Those series appear across the 245/45R18 and 245/40R19 radial fitments, depending on the exact wheel size used by the car.
Series names matter because they help distinguish the products in the grid beyond simple size matching. Once the correct 18-inch or 19-inch fitment is confirmed, a buyer can compare which series align with the car’s use, while also checking rim-width compatibility and load information where it is stated.
Restoration & Appearance
Which tire should I choose for a period-style 2008 Pontiac G8?
A period-style 2008 Pontiac G8 tire choice starts with staying in the correct original-type fitment for the car’s wheel setup, either 245/45R18 or 245/40R19. Since the available products are modern radial blackwall performance tires, the appearance remains consistent with the G8’s late-2000s factory-era look.
For a cleaner restoration-oriented presentation, it makes sense to keep the wheel diameter and tire size aligned with the correct sub-model rather than chasing a more aggressive alternative. Buyers focused on exact historical detail should also compare the car against marque references, window-sticker records, or original delivery documentation.
Does correct tire fitment matter for a 2008 Pontiac G8 restoration?
Yes, correct tire fitment matters on a 2008 Pontiac G8 restoration because the model used more than one wheel-and-tire package. A G8 built around the 245/45R18 setup presents differently from a GT w/Sport Pkg. (Summer Only) using 245/40R19, even though both are modern radial blackwall fitments.
Restoration-minded buyers usually benefit from matching the tire size to the exact sub-model before comparing tire series. That keeps the overall look closer to the car’s proper late-2000s presentation and helps avoid visual mismatches caused by incorrect wheel diameter, altered ride height, or non-matching replacement wheels.
Fitment, Maintenance & Road Use
Can modifications affect tire fitment on a 2008 Pontiac G8?
Yes, modifications can affect tire fitment on a 2008 Pontiac G8 even when the tire size itself is correct on paper. Aftermarket wheels, suspension changes, lowering, brake upgrades, or body alterations can change clearance at the fenders, steering components, and inner wheelhouse areas.
A G8 that has been modified should be checked for actual wheel diameter, width, and general clearance before new tires are selected. That matters especially when moving between the 18-inch and 19-inch fitment groups, since the tire must suit both the wheel and the physical space available on the car.
What should I inspect before driving a 2008 Pontiac G8 on new tires?
Before driving a 2008 Pontiac G8 on new tires, inspect the wheels for correct diameter and condition, confirm the tire size matches the sub-model, and check that the tires are mounted and inflated properly. It also helps to verify that the car does not have rubbing at full steering lock or over suspension movement.
Road-ready inspection should also include alignment condition, lug hardware, and any signs of suspension wear that could affect tire behavior. On a performance sedan like the G8, uneven wear patterns, damaged bushings, or neglected shocks can shorten tire life and make even a correctly sized new tire feel wrong.
How often should tires on a 2008 Pontiac G8 be inspected?
Tires on a 2008 Pontiac G8 should be inspected regularly, especially if the car sees spirited use, long highway miles, or extended storage between drives. Look for uneven tread wear, sidewall cuts, cracking, punctures, bulges, and persistent pressure loss, and compare all four tires for signs of setup or alignment issues.
A practical routine is to check condition and pressure before longer drives and to give the tires a closer inspection at normal service intervals. Cars that sit for stretches deserve extra attention, since aging, flat spotting, and slow air loss can become concerns even when the tread still looks usable.
