2026 GMC Acadia AT4
The 2026 GMC Acadia AT4 tire size and wheel specifications below reflect standard OEM reference fitment data for this trim level.
Detailed tire and wheel breakdown for the 2026 GMC Acadia
Tire geometry â 265/65R18
The 265/65R18 fitted to the 2026 GMC Acadia has a section width of 265mm and an aspect ratio of 65%, mounted on a 18-inch rim. That gives a sidewall height of 172.3mm (6.78") and an overall outside diameter of 801.7mm (31.56"). At highway speed this tire completes roughly 397 revolutions per kilometre, which is what your speedometer and odometer are calibrated against.
Plus-sizing window
If you want to upsize wheels on the 2026 GMC Acadia while keeping the speedometer accurate, target a 275/58R19 (plus-one). For a softer ride or winter setup, a 255/73R17 (minus-one) keeps the overall diameter within Âą3% of stock, which is the industry tolerance for ABS and stability control to stay calibrated.
Wheel fitment specs
The 2026 GMC Acadia uses a 6x139.7 bolt pattern with a 78.1mm hub bore. Safe rim width range for the OEM tire is 7.5J â 8.5J, and offsets in the ET45 â ET55 window will clear suspension and fender without rubbing on most setups.
Tire pressure guidance
Manufacturer-recommended cold tire pressure for the 2026 GMC Acadia is printed on the driver-side door jamb sticker â always defer to that value, not to the maximum pressure printed on the tire sidewall. Check pressure monthly and before long trips; under-inflation by 20% can reduce tread life by 25%.
Fitment Specifications
| Engine & Trim | Tire Size | Rim Size | Offset (ET) |
|---|---|---|---|
| AT4 | 265/65R18 | 18" x 8.0 | ET50 |
Frequently Asked Questions
What tire size does the 2026 GMC Acadia AT4 use?
The 2026 GMC Acadia AT4 uses 265/65R18 tires as standard equipment.
What is the bolt pattern of the 2026 GMC Acadia AT4?
The 2026 GMC Acadia AT4 has a 6x139.7 bolt pattern with a center bore of 78.1mm.
What is the wheel offset of the 2026 GMC Acadia AT4?
The 2026 GMC Acadia AT4 has a wheel offset of ETET50.