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) |
Imperial Match: 8x165.1 is commonly referred to as 8x6.5" in US Standard.
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.
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:
Expert Buying Guide for 1999 GMC 3500 Extended Cab
For your 1999 GMC 3500 Extended Cab, the 8x165.1 bolt pattern is unique to this year, so verify compatibility. The center bore is 116.7mm; aftermarket wheels often have a larger bore, requiring hub-centric rings to prevent vibration and ensure proper load distribution. Offset must stay within 20-40mm to avoid rubbing or suspension interference. Always use lug nuts with the correct 14x1.5 thread pitch and matching seat type (cone or ball seat) to prevent loosening. Failure to match these specs can lead to wheel separation. Re-torque after 50-100 miles.
Historical Fitment Data Reference
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
Quick Tips & Safety Warnings
- ✅ Re-torque lug nuts to 140 ft-lbs after 50-100 miles of driving.
- ✅ Use hub-centric rings with 116.7mm inner diameter to match the hub.
- ✅ Avoid wheels with offset outside 20-40mm to prevent brake caliper contact.
- ⚠️ 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).
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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.
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