Getting your wheel and tire fitment right is one of the most important — and most confusing — aspects of building a full-size truck. The wrong fitment rubs, the right fitment sits perfect. Here’s a practical guide.
Key Measurements
Bolt Pattern
All full-size Silverado and Sierra 1/2-tons from 1999+ use a 6x5.5" (6x139.7mm) bolt pattern. This is consistent across GMT800, GMT900, K2XX, and T1XX.
Older trucks:
- 1988–1998 GMT400: 6x5.5" (same)
- Pre-1988 C/K trucks: May vary — verify before ordering
Hub Bore
- GMT800 through T1XX: 78.1mm hub bore
- Aftermarket wheels with smaller hub bore need hub centric rings to avoid vibration
Offset (ET)
Offset determines where the wheel sits relative to the centerline of the hub.
- Positive offset: Wheel tucks in toward the hub (factory-style look)
- Zero offset: Wheel sits at hub centerline
- Negative offset: Wheel pushes outward (aggressive stance)
Most factory GM trucks: +24mm to +31mm offset
Popular lifted truck offset: 0mm to +18mm (for wider stance with leveled or lifted trucks)
Fitment by Generation
GMT800 (1999–2006)
- Stock: 17" or 20" wheels, 265/60R18 or 265/70R17
- Leveled (1.5"–2"): 285/65R18 or 275/65R20 fits clean
- 4" lift: 285/70R17 or 305/60R18
GMT900 (2007–2013)
- Stock: 17", 18", or 20" wheels
- Leveled 2": 285/65R20 or 285/70R17
- 4" lift: Up to 295/70R18 or 305/60R20
K2XX (2014–2018)
- Stock: 17", 18", 20", or 22" wheels
- Leveled 2": 285/65R20 fits great
- 4" lift: 305/60R20 or 35x12.50R20 on most builds
T1XX (2019+)
- Stock: 18", 20", 22" wheels
- Leveled 2": 295/65R20 or 285/70R17
- 4" lift: 305/65R18 or 35x12.50R18
Tire Type Guide
| Type | Best For |
|---|---|
| All-Season | Daily driver, mild winter, light off-road |
| All-Terrain (AT) | Mixed use, moderate off-road, most owners |
| Mud-Terrain (MT) | Serious off-road, heavy mud, reduced on-road life |
| Street/Performance | Lowered trucks, pavement only |
The BFGoodrich KO2 All-Terrain in LT265/65R18 is one of the most popular AT tires for full-size GM trucks — quiet enough for daily driving, capable enough for serious off-road.
Avoiding Rubbing
When going wider or taller:
- Check inner fender clearance at full turn
- Watch the rear of the front wheel well during suspension compression
- On lifted trucks, check the control arm-to-tire clearance at full droop
A quick test: Turn to full lock left and right with the truck at ride height — if it clears, you’re good. Then compress the suspension by pushing down on the front bumper and check again.