1999 GMC 3500 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 GMC 3500 Extended Cab, along with offset and center bore data.
| Bolt Pattern (Lug Pattern) | 8x165.1 (8x6.5") |
|---|---|
| Lug Nut / Bolt Size | 14x1.5 |
| Center Bore (CB) | 116.7 mm |
| Offset (ET) | 20-40 |
| Torque Specs | 140 ft-lbs (190 Nm) |
1999 3500 Extended Cab — Year-Specific Fitment Context
The 1999 is the only model year of the GMC 3500 Extended Cab in our database using the 8x165.1 bolt pattern.
Fitment Notes
The 1999 GMC 3500 Extended Cab has a bolt pattern of 8x165.1.
Imperial Conversion: This bolt pattern is commonly referred to as 8x6.5" in imperial units. When searching for aftermarket wheels, you may see them listed as 8x6.5".
This means it is a 8 lug pattern with a circle diameter of 165.1mm. When shopping for aftermarket wheels, ensure the "lug pattern" or "PCD" matches these numbers.
Year-to-Year Fitment Context
In our dataset, GMC 3500 Extended Cab appears from 1999 to 1999 (1 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: 60.0 mm
8x165.1 Pattern Context
This bolt pattern appears on 846 vehicles in our current database and is considered common.
Examples of other vehicles using 8x165.1:
1999 GMC 3500 Extended Cab — Frequently Asked Questions
What is the bolt pattern for a 1999 GMC 3500 Extended Cab?
The 1999 GMC 3500 Extended Cab uses a 8x165.1 bolt pattern (also called lug pattern or PCD). The center bore is 116.7mm and the offset is 20-40mm.
Will wheels from another GMC fit my 1999 3500 Extended Cab?
Only if they share the exact same 8x165.1 bolt pattern, a compatible offset, and a center bore equal to or larger than 116.7mm.
What is the factory wheel offset for a 1999 GMC 3500 Extended Cab?
The OEM offset for the 1999 3500 Extended Cab is typically around 20-40mm. Depending on wheel width, a deviation of ±5mm is usually acceptable, but verify suspension clearance.
How tight should I torque the lug nuts on a 1999 GMC 3500 Extended Cab?
Refer to your owner's manual for exact specs, but always tighten the 14x1.5 hardware in a star or crisscross pattern. Re-torque after the first 50 miles of driving.
Can I put aftermarket wheels on my 1999 GMC 3500 Extended Cab?
Absolutely. Just ensure the aftermarket wheels have a 8x165.1 bolt pattern, an offset near 20-40mm, and a center bore of at least 116.7mm (using hub rings if larger).
What lug nut size does the 1999 GMC 3500 Extended Cab use?
The 1999 GMC 3500 Extended Cab uses 14x1.5 lug nuts. Always verify the thread pitch and seat type (cone, ball, or flat) match your aftermarket wheels.
Fitment Checklist Before You Buy Wheels
- This fitment uses a wide offset range. Check brake clearance and fender clearance before buying wheels.
- Torque lugs in a star pattern to 140 ft-lbs (190 Nm), then re-check torque after 50-100 km (30-60 miles).
Editorial Fitment Notes
GMC 3500 Extended Cab is generally consistent in bolt-pattern records across model years, but offset and hardware should still be validated before purchase.
- Observed production years in our database: 1999-1999 (1 model years).
- Observed bolt-pattern variants: 1 (8x165.1).
- Observed total offset span across years: 60.0 mm.
- Observed center-bore variants: 1 | lug-size variants: 1.
Data Quality & Review
Source note: Compiled from manufacturer fitment references, historical wheel data, and internal normalization rules.
Last reviewed: 2026-05-26 | Reviewed by: Bolt Pattern HQ Editorial Team
If you find a discrepancy for 1999 GMC 3500 Extended Cab, please report it via our About page contact so we can verify and update this record.