2018 GMC Sierra 1500 — Tire Size & Pressure (OEM Specs)

Quick answer

• OEM tire size: Common factory fits include 255/70R17 (base), 265/65R18 (SLE/SLT/All Terrain), 275/55R20 (SLT/Denali); dealer/factory accessory 285/45R22 on select packages
• Recommended cold tire pressure (door placard): Most P-metric fits 35 psi front / 35 psi rear; trucks factory-equipped with LT tires may specify higher (often 50–60 psi rear, 50–55 psi front). Always follow your door placard
• Bolt pattern: 6x139.7 mm (6x5.5")
• Wheel size (OEM): 17x8, 18x8.5, 20x9 (22x9 accessory); typical OEM offsets +24 to +31 mm; hub bore 78.1 mm; lug nuts M14x1.5
• Load index/speed rating (typical): 110–114 load index; S–T (some 22" H) speed rating depending on size/brand. Verify on your tire sidewall
• Spare tire size: Full-size 17" steel spare, commonly 255/70R17 or 265/70R17 depending on package (some LT-designated spares on off-road packages)
• TPMS frequency: 315 MHz in North America (some export markets use 433 MHz)

Tire sizes by trim

Note: Packages and regional equipment can change tire fitment. Always confirm the size and PSI on your driver-door placard.

Recommended replacement tires

• Premium highway/all-season: Michelin Defender LTX M/S (or Defender LTX M/S2 where available) — excellent tread life, wet braking, and ride comfort. Typical street price: $210–$320 per tire (18–20 in)
• Premium all-terrain: BFGoodrich All-Terrain T/A KO2 (LT sizes) — proven off-road traction with strong load capacity; expect firmer ride. ~$230–$360 per tire
• Mid-tier all-terrain: Falken WildPeak A/T3W or Cooper Discoverer AT3 4S — balanced snow/wet grip with quieter highway manners than more aggressive A/Ts. ~$185–$300 per tire
• Mid-tier highway: Bridgestone Dueler H/L Alenza or General Grabber HTS60 — good OE-like ride/handling at a friendlier price. ~$170–$280 per tire
• Value A/T or H/T: Goodyear Wrangler TrailRunner AT or Hankook Dynapro HT — solid light-truck performance on a budget. ~$150–$240 per tire

Select the load range and speed rating that meet or exceed your door placard. If you tow/haul often, LT (Load Range C/E) options in appropriate sizes can add stability, but follow the truck’s placard pressures when equipped.

When to inflate to max load psi (HD trucks only)

This guidance applies to 2500/3500 HD models. The 2018 Sierra 1500 is a half-ton; you should not inflate to the tire’s sidewall “max” pressure for everyday driving. Instead, use the door-placard pressures (typically 35 psi for P-metric). If your 1500 came from the factory with LT tires (certain off-road or max-trailer packages), your placard may call for higher pressures when loaded — use those values rather than the tire’s sidewall maximum.

Lug nut torque & pattern

• Lug pattern: 6-lug (6x139.7 mm / 6x5.5")
• Lug nut/thread: M14x1.5
• Torque spec: 140 lb-ft (190 N·m) is typical for the 2018 Sierra 1500. Retorque after 50–100 miles on new wheels or after tire service. Always confirm with the owner’s manual or service data for your exact trim.

Common tire issues for this vehicle

• Uneven shoulder wear: Leveling kits or worn front-end components can introduce extra negative camber/toe, chewing outer or inner shoulders. Get a post-lift alignment and check tie rods/ball joints
• Cupping/scalloping: Worn shocks or infrequent rotations (these trucks are hard on rears when unloaded) can lead to cupping. Rotate every 5,000–7,500 miles
• Highway vibration: Large-diameter wheels (20–22") are sensitive to balance and road-force variation. Request a road-force balance if you notice persistent shake
• TPMS relearn after rotation: 2018 Sierra 1500 requires a sensor relearn so the truck knows which corner is which. After rotation, perform the relearn procedure (or have a shop do it) to avoid incorrect warnings
• Fitment rub with upsized tires: Many owners fit 33s (e.g., 275/60R20 or 285/65R18). Mild trimming or additional offset may be needed; mind the OEM offset range (+24 to +31 mm) to keep fender and UCA clearance without stressing wheel bearings

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