2026 GMC Sierra 3500 HD AT4X — LT305/70R18
2026 GMC Sierra 3500 HD AT4X
- Factory size
- LT305/70R18
- Load / speed
- 126/123R
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What size tires does the 2026 GMC Sierra 3500 HD AT4X take?
The factory tire size for the 2026 GMC Sierra 3500 HD AT4X is LT305/70R18.
The catalog lists it at load index 126/123, speed rating R (up to 106 mph).
| Wheels | Size | Load index | Speed rating |
|---|---|---|---|
| All wheels | LT305/70R18 | 126/123 | R |
Confirm the size printed on the sidewall of your current tire or on the tire placard in the driver's door jamb before you buy. Replacement tires should meet or exceed the vehicle's load index and speed rating.