The 2018 Ram 2500 is one of the most popular three-quarter-ton heavy-duty pickups on American roads, prized for its Cummins diesel torque and payload capacity. Whether you're replacing a damaged wheel, upgrading to aftermarket alloys, or fitting a set of winter tires on steelies, knowing the exact 2018 Ram 2500 bolt pattern is the first step to a safe, vibration-free fitment.
This guide covers the precise bolt pattern, lug nut specifications, center bore diameter, and wheel torque values for every 2018 Ram 2500 trim — including the differences between single rear wheel (SRW) and dual rear wheel (DRW/Dually) configurations. We'll also address common fitment mistakes that can damage hubs or cause wheel separation.
2018 Ram 2500 Bolt Pattern & Wheel Specifications
| Specification | SRW (Single Rear Wheel) | DRW (Dually) |
|---|---|---|
| Bolt Pattern | 8 × 165.1 mm (8 × 6.5") | 8 × 165.1 mm (8 × 6.5") |
| Lug Count | 8 lugs | 8 lugs |
| Center Bore | 121.3 mm (4.78") | 121.3 mm (4.78") |
| Thread Size | M14 × 1.5 | M14 × 1.5 |
| Lug Nut Torque | 130 lb-ft (176 Nm) | 130 lb-ft (176 Nm) |
| Stock Wheel Size | 17" or 18" or 20" | 17" (steel) |
| Stock Offset (typical) | +19 mm to +28 mm | +0 mm to +10 mm (varies) |
| Lug Seat Type | 60° conical (acorn) | Flat seat with washer (DRW-specific) |
Understanding the 8x165.1mm Bolt Pattern
The 2018 Ram 2500 uses an 8-lug bolt pattern measuring 165.1 mm across opposing lug centers. In imperial terms, this is commonly called 8×6.5 inches. Both measurements describe the same circle — 165.1 mm is the metric equivalent of 6.5 inches.
This pattern is shared with other heavy-duty trucks including the Chevrolet Silverado 2500HD and GMC Sierra 2500HD (2011+ models), as well as older Ford Super Duty trucks (pre-2005 F-250/F-350 used 8×170mm, which is not compatible). This cross-compatibility opens up a wider selection of aftermarket wheels, but you must verify center bore and offset — not just bolt pattern.
Why Bolt Pattern Alone Isn't Enough
Matching the 8×165.1mm bolt circle is necessary but not sufficient. Three additional measurements determine whether a wheel will actually fit and ride safely:
- Center bore: The 121.3 mm hub bore must match precisely. A wheel with a smaller bore won't mount. A wheel with a larger bore can use hub-centric rings, but running without proper centering causes vibration and puts shear stress on the lug studs.
- Offset and backspacing: Incorrect offset changes scrub radius, stresses wheel bearings, and can cause tire rub on suspension components. The 2018 Ram 2500 SRW typically runs +19 mm to +28 mm offset on factory wheels.
- Lug seat type: Factory SRW wheels use 60° conical (acorn) lug nuts. Many aftermarket wheels require different seat types — using the wrong lug nut can allow the wheel to work loose under load.
Torque Specifications and Lug Nut Procedure
The 2018 Ram 2500 requires 130 lb-ft (176 Nm) of torque on all eight lug nuts. This applies to both SRW and DRW models. Under-torquing risks wheel separation; over-torquing can stretch or snap the M14 × 1.5 wheel studs — a failure that's especially dangerous when towing or hauling at the 2500's rated capacity.
Proper Torque Sequence
- Hand-thread all eight lug nuts until snug.
- Using a calibrated torque wrench, tighten in a star (criss-cross) pattern to 65 lb-ft (half torque).
- Repeat the star pattern at the full 130 lb-ft specification.
- After the first 50 miles of driving on newly installed wheels, re-torque all lug nuts to 130 lb-ft. This accounts for initial seating and any paint or corrosion compression.
Never use an impact wrench for final torque. Air guns and electric impacts routinely exceed 130 lb-ft and can stretch studs beyond their yield point. Use hand tools or set an impact to a low setting and finish with a torque wrench.
SRW vs. Dually (DRW) Wheel Differences
While both the SRW and DRW 2018 Ram 2500 share the same 8×165.1mm bolt pattern and 121.3 mm center bore, the lug seat type and wheel design differ significantly.
Dually rear wheels use a flat-seat lug nut with a separate washer, while the front wheels on a DRW may use conical seat. The rear dually wheels also have a different offset and dish to allow dual-wheel clearance. You cannot simply mount SRW wheels on the rear of a dually — the offset and load rating will be incorrect, and the inner/outer wheel pair won't mate properly.
If you're converting a DRW to SRW (a common modification for off-road builds), you'll need new SRW wheels with the correct +19 to +28 mm offset and conical-seat lug nuts, plus a hub-centric spacer or new hub if the SRW wheel bore doesn't match.
Factory Wheel and Tire Sizes by Trim
| Trim Level | Standard Wheel | Optional Wheel | Stock Tire Size |
|---|---|---|---|
| Tradesman | 17" steel | 18" aluminum | LT245/70R17E or LT275/70R18E |
| SLT / Big Horn | 18" aluminum | 20" aluminum | LT275/70R18E or LT275/65R20E |
| Laramie | 18" polished aluminum | 20" chrome | LT275/70R18E or LT275/65R20E |
| Laramie Longhorn | 20" polished | — | LT275/65R20E |
| Limited | 20" chrome | — | LT275/65R20E |
| Power Wagon | 17" beadlock-capable | — | LT285/70R17 |
The Power Wagon's 17" wheels have a more aggressive offset and are designed to clear the factory front locker and larger CV joints. Aftermarket wheel buyers should test-fit before committing, especially on Power Wagon trims with the factory sway bar disconnect and larger brake calipers.
Common Aftermarket Fitment Mistakes
1. Ignoring Center Bore
Many aftermarket 8×6.5" wheels are manufactured with a larger center bore (e.g., 125 mm or 130 mm) to fit multiple vehicle platforms. Running a non-hub-centric wheel without proper adapter rings transfers all lateral load to the lug studs. On a truck that tows 15,000+ pounds, this is a serious safety risk.
2. Wrong Offset for Lifted Setups
Owners running leveling kits or full suspension lifts often pair them with low-offset or negative-offset wheels for a wider stance. While this looks aggressive, it increases scrub radius, accelerates wheel bearing wear, and can cause bump steer. Stay within +10 mm to +25 mm offset for daily-driven 2018 Ram 2500 trucks.
3. Using Ford 8×170mm Wheels
Pre-2005 Ford Super Duty trucks use an 8×170mm bolt pattern — just 4.9 mm wider than the Ram's 8×165.1mm. These wheels will not center on the Ram hub and should never be forced onto the studs. The 4.9 mm difference creates an eccentric load that can crack wheels or snap studs.
4. Overlooking Load Rating
The 2018 Ram 2500's gross axle weight rating (GAWR) can exceed 6,000 lbs on the front and 7,000 lbs on the rear. Every wheel must carry a load rating sufficient for the axle it's mounted on. Aftermarket wheels rated for light-duty or half-ton trucks are not safe on a 2500, regardless of bolt pattern match.
How to Verify Your Bolt Pattern at Home
If you're unsure whether your 2018 Ram 2500 has the standard 8×165.1mm pattern (it does, on every factory configuration), here's how to measure:
- Count the lugs: The Ram 2500 has 8 lug nuts per wheel — this is consistent across all trims and configurations.
- Measure opposing lugs: On an 8-lug wheel, measure from the center of one stud to the center of the stud directly across from it. You should get 165.1 mm (6.5 inches).
- Check the center bore: Measure the hub pilot diameter — it should read 121.3 mm.
- Verify thread pitch: The studs are M14 × 1.5. A thread pitch gauge confirms this; a 14 mm × 2.0 nut (common on some imports) will thread on but cross-thread under torque.
Frequently Asked Questions
Will Chevy 2500HD wheels fit a 2018 Ram 2500?
2011+ Chevy Silverado 2500HD and GMC Sierra 2500HD wheels share the 8×165.1mm bolt pattern and a similar center bore (121.3 mm on many models). However, offset and brake caliper clearance may differ. Always test-fit one wheel on the front before purchasing a full set, and verify the center bore matches exactly — some GM wheels use a slightly different bore.
Can I use wheel spacers on my 2018 Ram 2500?
Hub-centric spacers up to 1/4" (6 mm) are generally safe if they maintain the 121.3 mm center bore and use grade 10.9 or higher studs. Thicker spacers change the effective offset and increase leverage on wheel bearings. For anything beyond 6 mm, consult a suspension specialist and ensure the spacer is rated for the Ram 2500's axle loads.
What size lug nuts does the 2018 Ram 2500 use?
Factory lug nuts are M14 × 1.5 thread with a 60° conical seat (SRW models) or flat seat with washer (DRW rear wheels). The hex size is 22 mm. When buying aftermarket lug nuts, match all three specifications — thread, pitch, and seat type.
Is the 2018 Ram 2500 bolt pattern the same as the Ram 1500?
No. The 2018 Ram 1500 uses a 5×139.7mm (5×5.5") bolt pattern with only five lugs. The 2500 and 3500 use the heavier-duty 8×165.1mm pattern. Wheels are not interchangeable between the 1500 and 2500 platforms.
Do all 2018 Ram 2500 trims have the same bolt pattern?
Yes. Every 2018 Ram 2500 — Tradesman, SLT, Big Horn, Laramie, Longhorn, Limited, and Power Wagon — uses the identical 8×165.1mm (8×6.5") bolt pattern with a 121.3 mm center bore. The differences between trims are wheel diameter, width, offset, and finish, not the bolt pattern itself.
Sources: Ram Trucks official specifications, Mopar parts catalog. Always verify fitment with your wheel manufacturer and a qualified tire shop before purchase.
