Quick Answer
- GMC's 2025 Sierra 1500 manual names 275/50R22, 275/60R20, LT265/60R20, LT265/70R17, LT275/65R18, LT275/70R18 (calculated diameters 32.83, 32.99, 32.52, 31.61, 32.07, 33.16 in).
- The 2024 and 2025 Sierra HD manuals name LT235/80R17, LT235/80R18, LT245/75R17, LT265/60R22, LT265/70R17, LT275/65R20, LT275/70R18 and LT305/70R18E. The manuals do not break sizes down by trim, so check the tire label on your driver's door.
- To check another size, open the Size Compare tab: it calculates the diameter change and speedometer error against your current size.
GMC-listed size comparisons: click to load
GMC Tire Sizes From Owner's Manuals
Sizes are as named in each manual. Diameters are calculated from the size.
| GMC model | Years | Manual section | Tire sizes | Diameter in (calc.) | Wheels |
|---|---|---|---|---|---|
| Sierra 1500 | 2025 | Tire chain section | 275/50R22, 275/60R20, LT265/60R20, LT265/70R17, LT275/65R18, LT275/70R18 | 32.83, 32.99, 32.52, 31.61, 32.07, 33.16 | Not listed |
| Sierra 1500 | 2019 | Tire chain section | 255/70R17, 265/70R17, 265/65R18 | 31.06, 31.61, 31.56 | Not listed |
| Sierra 2500 HD / 3500 HD | 2024 to 2025 | Tire chain section | LT235/80R17, LT245/75R17, LT265/70R17, LT275/70R18 | 31.80, 31.47, 31.61, 33.16 | Not listed |
| Acadia | 2024 | Tire chain section | 255/65R18 | 31.05 | Not listed |
| Acadia | 2020 | Sizes named in manual | 235/55R20, 235/65R18, 245/65R17, 255/65R17 | 30.18, 30.03, 29.54, 30.05 | Not listed |
GMC Tire Outer Diameter and Dimension Reference
Dimensions are calculated from the size with the ISO metric formulas. The last column shows which manual names the size.
| Tire size | Diameter in | Width in | Sidewall in | Circumference in | Revs per mile | Named in |
|---|---|---|---|---|---|---|
| 255/70R17 | 31.06 | 10.04 | 7.03 | 97.6 | 649 | Sierra 1500 (2019) |
| 265/70R17 | 31.61 | 10.43 | 7.30 | 99.3 | 638 | Sierra 1500 (2019) |
| 265/65R18 | 31.56 | 10.43 | 6.78 | 99.2 | 639 | Sierra 1500 (2019) |
| 275/50R22 | 32.83 | 10.83 | 5.41 | 103.1 | 614 | Sierra 1500 (2019 to 2025) |
| 275/60R20 | 32.99 | 10.83 | 6.50 | 103.6 | 611 | Sierra 1500 (2019 to 2025) |
| LT265/60R20 | 32.52 | 10.43 | 6.26 | 102.2 | 620 | Sierra 1500 (2021 to 2025) |
| LT265/70R17 | 31.61 | 10.43 | 7.30 | 99.3 | 638 | Sierra 1500; Sierra HD |
| LT275/65R18 | 32.07 | 10.83 | 7.04 | 100.8 | 629 | Sierra 1500 (2019 to 2025) |
| LT275/70R18 | 33.16 | 10.83 | 7.58 | 104.2 | 608 | Sierra 1500 (2025); Sierra HD |
| LT235/80R17 | 31.80 | 9.25 | 7.40 | 99.9 | 634 | Sierra HD |
| LT235/80R18 | 32.80 | 9.25 | 7.40 | 103.1 | 615 | Sierra HD |
| LT245/75R17 | 31.47 | 9.65 | 7.23 | 98.9 | 641 | Sierra HD |
| LT265/60R22 | 34.52 | 10.43 | 6.26 | 108.4 | 584 | Sierra HD |
| LT275/65R20 | 34.07 | 10.83 | 7.04 | 107.0 | 592 | Sierra HD |
| LT305/70R18E | 34.81 | 12.01 | 8.41 | 109.4 | 579 | Sierra HD |
| 255/65R18 | 31.05 | 10.04 | 6.53 | 97.6 | 650 | Acadia (2024) |
| 235/55R20 | 30.18 | 9.25 | 5.09 | 94.8 | 668 | Acadia (2020) |
| 235/65R18 | 30.03 | 9.25 | 6.01 | 94.3 | 672 | Acadia (2020) |
| 245/65R17 | 29.54 | 9.65 | 6.27 | 92.8 | 683 | Acadia (2020) |
| 255/65R17 | 30.05 | 10.04 | 6.53 | 94.4 | 671 | Acadia (2020) |
Speedometer Effect Between Sizes GMC Names
Each row compares two sizes that the same GMC manual names. Continental guidance is to keep the rolling circumference within 3%; the differences below are calculated.
| Model | Size A | Size B | Change (calc.) | True speed at 60 mph indicated |
|---|---|---|---|---|
| Sierra 1500 (2025) | 275/60R20 | 275/50R22 | -0.17 in (-0.5%) | 59.7 mph |
| Sierra 1500 (2025) | LT265/70R17 | LT275/65R18 | +0.47 in (+1.5%) | 60.9 mph |
| Sierra 1500 (2025) | LT275/65R18 | LT275/70R18 | +1.08 in (+3.4%) | 62.0 mph |
| Sierra HD (2025) | LT265/70R17 | LT275/70R18 | +1.55 in (+4.9%) | 62.9 mph |
| Sierra HD (2025) | LT275/70R18 | LT305/70R18E | +1.65 in (+5.0%) | 63.0 mph |
| Acadia (2020) | 235/65R18 | 235/55R20 | +0.15 in (+0.5%) | 60.3 mph |
How GMC Tire Sizes Are Calculated
Standard Metric Format (265/70R17) & LT Prefix
Metric Format (e.g. 265/70R17): Section width (in) = 265 ÷ 25.4 = 10.43" Sidewall (in) = 265 × 0.70 ÷ 25.4 = 7.30" Overall diameter = Rim + 2 × Sidewall = 17 + 14.61 = 31.61" Circumference = π × 31.61 = 99.3" Revs per mile = 63,360 ÷ 99.3 = 638 The LT prefix means Light Truck; the calculator uses the same formula for LT and P-metric sizes.
Gear Ratio With a Different Tire Size
Effective ratio with a new tire = axle ratio × (stock diameter ÷ new diameter) Ratio that restores the stock effective ratio = axle ratio × (new diameter ÷ stock diameter) Example: 3.42 axle, 275/60R20 (32.99") to 275/50R22 (32.83"): restores at 3.42 × 32.83 ÷ 32.99 = 3.40. GMC's owner's manuals do not list axle ratios.
Speedometer Correction
True speed = indicated speed × (new diameter ÷ stock diameter) Example: LT265/70R17 (31.61") to LT275/65R18 (32.07"): 60 mph indicated = 60 × 32.07 ÷ 31.61 = 60.9 mph.
How to Use This GMC Tire Size Calculator
- 1Look up GMC tire sizes: Go to the GMC Sizes tab and select your model and year. The tire sizes named in the owner's manual appear, with the diameter calculated from the size. The manuals do not list sizes by trim, so confirm with the tire label on your driver's door.
- 2Enter your stock and new tire size: In the Size Compare tab, enter your current size and the size you are considering, in the format 265/70R17 or LT275/65R18. The calculator shows the diameter change, sidewall and width change, revolutions per mile and a speedometer table.
- 3Enter your axle ratio (optional): If you know your axle ratio, enter it to see the ratio that would restore the stock effective ratio. The ratio is not in GMC's owner's manuals; check the RPO code label.
- 4Read the result: Continental guidance is to keep the rolling circumference within 3%; it is not a GMC specification. For anything beyond that, or any size the manual does not name, check with a GMC dealer.
GMC Tire Rules Every Owner Should Know
Use the correct wheels
GMC's manuals say to replace wheels, wheel bolts, wheel nuts and TPMS sensors with new GM original equipment parts, and warn that the wrong wheel can affect bearing life, brake cooling, speedometer or odometer calibration, headlamp aim, bumper height, ground clearance, and tire or chain clearance.
Tire chains
On the 2025 Sierra 1500, GMC says not to use chains on 275/50R22, 275/60R20, LT265/60R20, LT265/70R17, LT275/65R18 or LT275/70R18. On the Sierra HD, LT235/80R17 takes chains on the rear axle only, and LT245/75R17, LT265/70R17 and LT275/70R18 on front and rear. The Acadia (2024) takes chains only on 255/65R18, and the Canyon and Terrain manuals say not to use chains.
Wheel nut torque
140 lb ft (190 N·m) for the Sierra, Canyon and Acadia, 100 lb ft (140 N·m) for the Terrain.
What the manuals do not list
Tire sizes by trim, bolt pattern, offset, lift limits, fender clearance and axle ratios. Check these with a GMC dealer or the tire label on your driver's door.
For the items the manuals leave out, the wheel offset and backspacing converter helps with wheels and the effective gear ratio calculator with axle ratios. The sister truck is covered in the Chevrolet Silverado tire guide.