2008 GMC Sierra 1500 Extended Cab Bolt Pattern
Checking fitment for your vehicle? Below you will find the factory bolt pattern (also known as the lug pattern) for the 2008 GMC Sierra 1500 Extended Cab, along with offset and center bore data.
| Bolt Pattern (Lug Pattern) | 6x139.7 (6x5.5") |
|---|---|
| Lug Nut / Bolt Size | 14x1.5 |
| Center Bore (CB) | 78.1 mm |
| Offset (ET) | 20-30 |
| Torque Specs | 100 ft-lbs (135 Nm) |
Imperial Match: 6x139.7 is commonly referred to as 6x5.5" in US Standard.
2008 Sierra 1500 Extended Cab — Year-Specific Fitment Context
The 2008 GMC Sierra 1500 Extended Cab is in year 10 of 15 using the 6x139.7 pattern (1999–2013). Wheels from any 1999–2013 GMC Sierra 1500 Extended Cab are cross-compatible with the 2008 model.
GMC Sierra 1500 Extended Cab Bolt Pattern by Year
The table below shows how the Sierra 1500 Extended Cab's wheel specifications have changed over the years. The 2008 model year is highlighted.
| Year | Bolt Pattern | Center Bore | Offset |
|---|---|---|---|
| 1999 | 6x139.7 | 78.1 | 20-30 |
| 2000 | 6x139.7 | 78.1 | 20-30 |
| 2001 | 6x139.7 | 78.1 | 20-30 |
| 2002 | 6x139.7 | 78.1 | 20-30 |
| 2003 | 6x139.7 | 78.1 | 20-30 |
| 2004 | 6x139.7 | 78.1 | 20-30 |
| 2005 | 6x139.7 | 78.1 | 20-30 |
| 2006 | 6x139.7 | 78.1 | 20-30 |
| 2007 | 6x139.7 | 78.1 | 20-30 |
| ▸ 2008 | 6x139.7 | 78.1 | 20-30 |
| 2009 | 6x139.7 | 78.1 | 20-30 |
| 2010 | 6x139.7 | 78.1 | 20-30 |
| 2011 | 6x139.7 | 78.1 | 20-30 |
| 2012 | 6x139.7 | 78.1 | 20-30 |
| 2013 | 6x139.7 | 78.1 | 20-30 |
6x139.7 Pattern Context
This bolt pattern appears on 1067 vehicles in our current database and is considered common.
Examples of other vehicles using 6x139.7:
Expert Buying Guide for 2008 GMC Sierra 1500 Extended Cab
For your 2008 GMC Sierra 1500 Extended Cab, the bolt pattern is 6x139.7mm with a critical center bore of 78.1mm. Aftermarket wheels often have a larger bore, requiring hub-centric rings to prevent vibration and ensure proper load distribution. The offset range is 20-30mm; staying within this range maintains suspension geometry and prevents rubbing. Always use the correct lug nuts: 14x1.5 thread pitch with a cone or ball seat matching the wheel. Incorrect lug nuts can cause wheel separation. Re-torque after 50-100 miles of driving.
Historical Fitment Data Reference
In our dataset, GMC Sierra 1500 Extended Cab appears from 1999 to 2013 (15 model years). Across recorded model years, this model generally keeps the same bolt pattern.
- Observed bolt-pattern variants for this model: 1
- Observed center-bore variants for this model: 1
- Observed lug-size variants for this model: 1
- Observed total offset span across years: 50.0 mm
Quick Tips & Safety Warnings
- ✅ Re-torque lug nuts to 140 ft-lbs after 50-100 miles to ensure proper seating.
- ✅ Avoid wheels with offset below 20mm to prevent tire rubbing on suspension components.
- ✅ Check that aftermarket wheels include hub-centric rings for the 78.1mm bore to avoid vibrations.
- ⚠️ This fitment uses a wide offset range. Check brake clearance and fender clearance before buying wheels.
- ⚠️ Torque lugs in a star pattern to 100 ft-lbs (135 Nm), then re-check torque after 50-100 km (30-60 miles).
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2008 GMC Sierra 1500 Extended Cab — Frequently Asked Questions
What is the bolt pattern for a 2008 GMC Sierra 1500 Extended Cab?
The 2008 GMC Sierra 1500 Extended Cab uses a 6x139.7 bolt pattern (also called lug pattern or PCD). The center bore is 78.1mm and the offset is 20-30mm.
What other years of GMC Sierra 1500 Extended Cab have the same bolt pattern as the 2008?
The GMC Sierra 1500 Extended Cab uses the 6x139.7 pattern from 1999 through 2013. Wheels from any of these model years are dimensionally compatible with the 2008, provided the offset and center bore also match.
Do 2008 GMC Sierra 1500 Extended Cabs use lug bolts or lug nuts?
The 2008 Sierra 1500 Extended Cab requires 14x1.5 hardware. Check your specific trim to ensure you use the correct conical or spherical seating.
What does 20-30mm offset mean for the 2008 Sierra 1500 Extended Cab?
An offset of 20-30mm means the wheel's mounting surface is 20-30mm away from its centerline. Changing this value drastically can affect suspension geometry and wheel bearing wear on your GMC.
What is the factory wheel offset for a 2008 GMC Sierra 1500 Extended Cab?
The OEM offset for the 2008 Sierra 1500 Extended Cab is typically around 20-30mm. Depending on wheel width, a deviation of ±5mm is usually acceptable, but verify suspension clearance.
Why is matching the 78.1mm center bore important for the 2008 Sierra 1500 Extended Cab?
The 78.1mm center bore ensures the wheel is perfectly centered on the hub. If the wheel is lug-centric instead of hub-centric, you may experience steering wheel vibration at highway speeds.
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