The 2018 Mercedes-Benz Trucks GLS63 AMG blends full-size SUV luxury with the kind of power and road presence that makes wheel-and-tire fitment especially important. On a vehicle like this, tire choice affects not just appearance, but the way the SUV sits, clears, and responds in everyday driving. The 2018 Mercedes-Benz Trucks GLS63 AMG uses radial tires in two primary sizes, 295/40R21 and 285/40R22, so the first step is confirming which wheel diameter is on the vehicle. Once that is established, the decision shifts to selecting the right metric radial size and checking overall dimensions against the current wheel and suspension setup.
Which Tire Size Is Right for The 2018 Mercedes-Benz Trucks GLS63 AMG
Two primary tire sizes apply to the 2018 Mercedes-Benz Trucks GLS63 AMG, and both are radial metric fitments tied to different wheel diameters. The Base sub-model can use either 295/40R21 or 285/40R22, which makes confirming the actual rim diameter on the vehicle the most important first step before comparing tire choices or replacing a worn set.
The 285/40R22 size uses modern metric sizing: 285 is the nominal section width in millimeters, 40 is the aspect ratio, R identifies radial construction, and 22 is the wheel diameter in inches. On the 2018 Mercedes-Benz Trucks GLS63 AMG, this is a low-profile radial fitment built around a 22-inch wheel. That makes wheel confirmation especially important, since this size is tied to a larger rim than the alternate fitment. It is the right size to evaluate when the vehicle is already equipped with 22-inch wheels and the goal is to stay with the established fitment.
The 295/40R21 size is also a modern metric radial, with a 295-millimeter nominal section width, a 40-series aspect ratio, and fitment on a 21-inch wheel. For the 2018 Mercedes-Benz Trucks GLS63 AMG, this size represents a distinct primary setup rather than a simple variation of the 22-inch option. Its role in tire selection is straightforward: it belongs on vehicles running 21-inch rims, so the wheel diameter must match before anything else is considered. Buyers comparing replacements should use this size only after verifying the current wheel package on the SUV.
Sub-model fitment is straightforward here because the covered configuration is the 2018 Mercedes-Benz Trucks GLS63 AMG Base. Tire choice still requires attention, however, because that sub-model can use either of two radial sizes depending on whether the vehicle has 21-inch or 22-inch wheels.
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2018 Mercedes-Benz Trucks GLS63 AMG Base
The 2018 Mercedes-Benz Trucks GLS63 AMG Base uses radial tire fitments in both 295/40R21 and 285/40R22. That means tire selection starts with confirming which wheel diameter is actually on the vehicle, then matching the replacement tire to that specific rim and overall setup.
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
Common questions for the 2018 Mercedes-Benz Trucks GLS63 AMG usually center on the two primary tire sizes, 21-inch versus 22-inch wheel fitment, and what to inspect before replacing tires on a high-performance luxury SUV.
Tire Size & Fitment
What tire size fits a 2018 Mercedes-Benz Trucks GLS63 AMG?
The 2018 Mercedes-Benz Trucks GLS63 AMG uses two primary radial tire sizes: 295/40R21 and 285/40R22. Both sizes apply to the GLS63 AMG Base, and each one corresponds to a different wheel diameter rather than a single universal setup.
The key step is checking the wheels currently on the vehicle before ordering replacements. A 21-inch wheel requires 295/40R21, while a 22-inch wheel requires 285/40R22. If the SUV has aftermarket wheels or a changed suspension setup, it is smart to confirm wheel width, tire clearance, and the actual size mounted now instead of relying on appearance alone.
What size rim does a 2018 Mercedes-Benz Trucks GLS63 AMG use?
The 2018 Mercedes-Benz Trucks GLS63 AMG uses either a 21-inch or 22-inch rim, depending on which of its two primary tire sizes is on the vehicle. The 295/40R21 size fits a 21-inch wheel, and the 285/40R22 size fits a 22-inch wheel.
That difference matters because the two tire sizes are not meant for the same rim diameter. A quick check of the current tire sidewall or the wheel itself usually confirms which setup is installed. On any GLS63 AMG that has had wheels changed, measuring and verifying the actual rim size is the safest way to avoid choosing the wrong tire.
Why does the 2018 Mercedes-Benz Trucks GLS63 AMG have more than one tire size?
The 2018 Mercedes-Benz Trucks GLS63 AMG has more than one tire size because it can be equipped with different wheel diameters. Its two primary radial fitments, 295/40R21 and 285/40R22, support distinct 21-inch and 22-inch wheel setups on the same model.
That means the correct replacement is determined by the wheels actually on the SUV, not just by the model name. Owners should confirm the tire size stamped on the current sidewall and match the rim diameter exactly. This is especially important on vehicles that may have had wheel upgrades, replacement rims, or other appearance-oriented changes during ownership.
Choosing the Right Tire
What should I consider when choosing a tire for a 2018 Mercedes-Benz Trucks GLS63 AMG?
Start with the correct primary size for the wheel already on the vehicle. The 2018 Mercedes-Benz Trucks GLS63 AMG uses either 295/40R21 or 285/40R22, both in radial construction, so selecting by rim diameter is the first requirement before comparing anything else.
Once the size is confirmed, look at how the tire matches the SUV's current setup and use. A replacement should suit the wheel dimensions, maintain proper clearance, and be appropriate for the vehicle's weight and driving role. On a GLS63 AMG with non-original wheels, checking the existing fitment carefully helps prevent problems with rubbing, stance, or mismatched proportions.
How do I choose between the available 2018 Mercedes-Benz Trucks GLS63 AMG tire sizes?
There is no general choice between the two primary sizes unless the wheel setup is being changed. The 2018 Mercedes-Benz Trucks GLS63 AMG uses 295/40R21 on a 21-inch rim and 285/40R22 on a 22-inch rim, so the wheel diameter determines which size belongs on the vehicle.
If the SUV already has its wheels installed, the correct path is to match that existing diameter exactly. If a wheel change is part of the plan, tire selection becomes part of a broader fitment decision that should include wheel width, clearance at full steering lock, and the vehicle's overall stance. Treat the size as part of the complete package, not an isolated number.
What rim-fitment details should I compare when choosing 2018 Mercedes-Benz Trucks GLS63 AMG tires?
The most important rim-fitment detail is diameter, because the 2018 Mercedes-Benz Trucks GLS63 AMG uses two different setups: 21-inch wheels with 295/40R21 tires and 22-inch wheels with 285/40R22 tires. A mismatch between tire size and rim diameter is the fastest way to end up with the wrong replacement.
Wheel width and overall vehicle clearance also deserve attention, especially on an SUV that may have been customized. A tire can have the correct diameter in name but still create issues if the wheel dimensions or offsets differ from the current setup. Comparing the mounted size already on the vehicle against the replacement plan helps keep the fitment process accurate.
Restoration & Appearance
Does correct tire fitment matter for a 2018 Mercedes-Benz Trucks GLS63 AMG restoration or preservation project?
Yes, correct tire fitment matters because the 2018 Mercedes-Benz Trucks GLS63 AMG was built around specific low-profile radial sizes on either 21-inch or 22-inch wheels. Using the proper size helps preserve the vehicle's intended proportions and avoids turning a straightforward replacement into a clearance or handling issue.
On a preservation-minded example, matching the existing wheel-and-tire format usually makes the most sense unless there is a clear reason to change it. Owners should confirm the current setup carefully, especially if the SUV has passed through multiple hands. Keeping the fitment consistent supports a more authentic overall presentation, even on a relatively modern collector vehicle.
How does tire size affect the appearance of a 2018 Mercedes-Benz Trucks GLS63 AMG?
Tire size has a strong visual effect on the 2018 Mercedes-Benz Trucks GLS63 AMG because its two primary fitments are built around different wheel diameters. A 295/40R21 setup presents a 21-inch wheel package, while 285/40R22 places the SUV on a visibly larger 22-inch rim with a similarly low-profile radial look.
Appearance changes become more noticeable when a vehicle has altered wheels, lowered suspension, or nonstandard tire replacements. Keeping the tire matched to the intended wheel diameter helps maintain balanced proportions and proper visual fill in the wheel opening. Before changing sizes for style alone, it is wise to check clearance and the overall effect on the SUV's stance.
Fitment, Maintenance & Road Use
Can modifications affect tire fitment on a 2018 Mercedes-Benz Trucks GLS63 AMG?
Yes, modifications can affect tire fitment on a 2018 Mercedes-Benz Trucks GLS63 AMG. Wheel changes, altered offsets, suspension lowering, and body modifications can all change the space available for either 295/40R21 or 285/40R22, even when the tire size itself is one of the standard fitments for the model.
A modified vehicle should be checked at full steering lock and through suspension travel before assuming the same size will still behave the same way. Looking at current wheel dimensions, visible clearance, and any signs of rubbing around the fenders or inner liners helps confirm whether the established fitment still suits the SUV's present configuration.
What should I inspect before driving a 2018 Mercedes-Benz Trucks GLS63 AMG on new tires?
Before driving a 2018 Mercedes-Benz Trucks GLS63 AMG on new tires, inspect the tire size, mounting direction if applicable, inflation pressure, and overall seating on the wheel. It is also important to confirm that all four tires match the intended wheel diameter and that there is no obvious interference around the fenders or suspension.
A short visual check after installation can prevent avoidable problems. Look for uneven gaps, contact marks, or anything that suggests the tire is too close to body or chassis components. After the first miles, rechecking pressure and giving the tires another inspection helps confirm that the replacement size is behaving properly on the vehicle's current setup.
How often should tires on a 2018 Mercedes-Benz Trucks GLS63 AMG be inspected?
Tires on a 2018 Mercedes-Benz Trucks GLS63 AMG should be inspected regularly, not just when tread looks low. A quick check for air loss, cuts, bulges, sidewall damage, and irregular wear helps catch problems early, especially on low-profile radial tires where wheel and curb damage can become an issue.
Routine inspection matters even more if the SUV is driven infrequently or stored for long periods. Collector-minded or seasonal-use vehicles can develop age-related concerns despite limited mileage. Checking condition before longer trips, after storage, and anytime ride quality or steering feel changes is a practical habit that supports both safety and fitment confidence.
