1999 Chevrolet 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 1999 Chevrolet 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) | 24-28 |
| Torque Specs | 100 ft-lbs (135 Nm) |
Imperial Match: 6x139.7 is commonly referred to as 6x5.5" in US Standard.
1999 1500 Extended Cab — Year-Specific Fitment Context
The 1999 model year is the final year of the Chevrolet 1500 Extended Cab's 6x139.7 bolt pattern run (since 1992). Wheels from any 1992–1999 Chevrolet 1500 Extended Cab are cross-compatible with the 1999 model.
Chevrolet 1500 Extended Cab Bolt Pattern by Year
The table below shows how the 1500 Extended Cab'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 Chevrolet 1500 Extended Cab
For your 1999 Chevrolet 1500 Extended Cab, the 6x139.7 bolt pattern and 78.1mm center bore are critical. Aftermarket wheels often have a larger center bore (e.g., 78.3mm or 108mm), requiring hub-centric rings to prevent vibration and ensure load is carried by the hub, not the lug nuts. Offset must stay within 24-28mm; deviations can cause tire rubbing on suspension or fenders. Always use 14x1.5 lug nuts with the correct seat type—factory wheels use a conical (60-degree) seat, while aftermarket may require ball or shank-style nuts. Improper seating can lead to wheel loosening. Re-torque after 50-100 miles.
Historical Fitment Data Reference
In our dataset, Chevrolet 1500 Extended Cab 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: 52.0 mm
Quick Tips & Safety Warnings
- ✅ Re-torque lug nuts to 140 ft-lb after 50-100 miles of driving.
- ✅ If using aftermarket wheels, verify hub-centric ring inner diameter matches 78.1mm and outer diameter matches wheel bore.
- ✅ Avoid wheels with offset below 24mm (too aggressive) or above 28mm (too tucked) to prevent clearance issues.
- ⚠️ 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 Chevrolet 1500 Extended Cab — Frequently Asked Questions
What is the bolt pattern for a 1999 Chevrolet 1500 Extended Cab?
The 1999 Chevrolet 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 24-28mm.
What other years of Chevrolet 1500 Extended Cab have the same bolt pattern as the 1999?
The Chevrolet 1500 Extended Cab 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.
Do 1999 Chevrolet 1500 Extended Cabs use lug bolts or lug nuts?
The 1999 1500 Extended Cab requires 14x1.5 hardware. Check your specific trim to ensure you use the correct conical or spherical seating.
What does 24-28mm offset mean for the 1999 1500 Extended Cab?
An offset of 24-28mm means the wheel's mounting surface is 24-28mm away from its centerline. Changing this value drastically can affect suspension geometry and wheel bearing wear on your Chevrolet.
Why is matching the 78.1mm center bore important for the 1999 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.
How do I measure the bolt pattern on my 1999 Chevrolet?
The 1999 1500 Extended Cab 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.
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