1999 GMC Suburban 1500 Bolt Pattern
Checking fitment for your vehicle? Below you will find the factory bolt pattern (also known as the lug pattern) for the 1999 GMC Suburban 1500, 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.
1999 Suburban 1500 — Year-Specific Fitment Context
The 1999 model year is the final year of the GMC Suburban 1500's 6x139.7 bolt pattern run (since 1992). Wheels from any 1992–1999 GMC Suburban 1500 are cross-compatible with the 1999 model.
GMC Suburban 1500 Bolt Pattern by Year
The table below shows how the Suburban 1500's wheel specifications have changed over the years. The 1999 model year is highlighted.
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 1999 GMC Suburban 1500
For your 1999 GMC Suburban 1500, the 6x139.7 bolt pattern is shared with 1992-1999 models, but the 78.1mm center bore is critical. Aftermarket wheels often have larger bores, requiring hub-centric rings to prevent vibration and stress on lug studs. Offset must stay within 20-30mm; deviations risk rubbing or poor handling. Always use 14x1.5 lug nuts with the correct seat type (cone or ball) matching your wheels. Improper seating can cause loosening and wheel loss. Verify wheel load rating exceeds your vehicle's GVWR.
Historical Fitment Data Reference
In our dataset, GMC Suburban 1500 appears from 1992 to 1999 (8 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 after 50-100 miles of driving to ensure proper seating.
- ✅ Avoid wheels with offset below 20mm (too aggressive) or above 30mm (too tucked) to prevent clearance issues.
- ✅ If using aftermarket wheels, always install hub-centric rings to match the 78.1mm center bore exactly.
- ⚠️ 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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1999 GMC Suburban 1500 — Frequently Asked Questions
What is the bolt pattern for a 1999 GMC Suburban 1500?
The 1999 GMC Suburban 1500 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 Suburban 1500 have the same bolt pattern as the 1999?
The GMC Suburban 1500 uses the 6x139.7 pattern from 1992 through 1999. Wheels from any of these model years are dimensionally compatible with the 1999, provided the offset and center bore also match.
Why is matching the 78.1mm center bore important for the 1999 Suburban 1500?
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.
How do I measure the bolt pattern on my 1999 GMC?
The 1999 Suburban 1500 uses a 6x139.7 pattern. For 4, 6, or 8-lug wheels, measure center-to-center across opposite holes. For 5-lug, measure from the center of one hole to the back of the opposite hole.
What lug nut size does the 1999 GMC Suburban 1500 use?
The 1999 GMC Suburban 1500 uses 14x1.5 lug nuts. Always verify the thread pitch and seat type (cone, ball, or flat) match your aftermarket wheels.
Do 1999 GMC Suburban 1500s use lug bolts or lug nuts?
The 1999 Suburban 1500 requires 14x1.5 hardware. Check your specific trim to ensure you use the correct conical or spherical seating.
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