Overview

Overview
This new 2026 Peterbilt 579 conventional is configured as a tandem-axle sleeper tractor with an 80" Ultraloft sleeper, set up for general freight hauling and rated to pull a 53' van-type trailer (13.50' trailer height, 36" kingpin setting, two trailer axles). GVWR is 52,000 lbs with a 240" wheelbase, 171.80" cab-to-axle, and 227.80" cab-to-end-of-frame.

Engine & Drivetrain
Powered by a PACCAR MX-13 engine rated at 455 HP @ 1,600 RPM (governed at 2,200 RPM) with 1,650 lb-ft of torque @ 900 RPM, 2024-emissions/CARB compliant. Runs PACCAR's EMUX electronics architecture with preferred EIST settings, engine idle shutdown timer, effective VSL setting of 65.0 MPH, and a typical operating speed of 65 MPH. Equipped with MX retarder state cruise control, predictive cruise control package, and engine monitoring protection (derate) on the PACCAR MX. Compression brake included, with engine brake controls located on the RH steering column. Paired with a PACCAR TX-12 PO-16F112C12 automated 12-speed transmission (no cooler), column-mounted RH shifter, economy shift calibration, and neutral coast mode. RPL20 interaxle driveline and RPL25 SD driveline with one midship bearing. Electrical system includes a PACCAR 160-amp brushed alternator, three PACCAR premium 12V dual-purpose batteries (2,190 CCA total), low voltage disconnect system, and a 110–120V immersion-type block heater. Cooling and exhaust equipment includes a variable-speed direct-drive fan clutch, Wabco 25.9 CFM air compressor, PACCAR fuel/water separator with extended service interval, a high-efficiency cooling system, and a single RH horizontal DPF/SCR module with a dash-mounted regeneration switch.

Chassis & Axles
Front axle: Meritor MFS+12E rated 12,500 lbs (12,000 lb GAWR) with a 3.5" drop, taper leaf springs, 12,000-lb shocks, TRW THP60 power steering with a frame-mounted reservoir, PHP10 aluminum preset+ hubs (air disc), Bendix ADB22X-LT front disc brakes, Tenneco steer axle shocks, and 30mm front spring spacer blocks. Rear axle: PACCAR DX-40 rated 40,000 lbs (20,000 lb GAWR per axle, tandem) with a 2.85 rear axle ratio, PHP10 aluminum preset+ hubs (air disc), Bendix ADB22X-LT tandem drive disc brakes, and synthetic axle lubricant on all axles. Frame is built with 10-5/8" steel rails (326"–384" length, 5/16" rail thickness) and aluminum frame rail crossmembers, with a tapered end-of-frame tractor crossmember and kingpin cutout. Fifth wheel is a Jost JSK37 top plate, inboard-mounted on an 18" air slide (Jost lightweight inboard slider) set at the centerline of the bogie, 6.6"–7" fifth wheel height, plus a frame-mounted deck plate and access package on the LH side. Safety systems include Bendix ESP electronic stability program with ATC, Bendix collision mitigation (RH side sensor), adjustable and standard following-distance adaptive cruise control, Bendix Fusion stop-and-go advanced, 6-channel ABS, and a tire pressure monitoring system.

Suspension
PB low air leaf rear suspension rated 40,000 lbs in a 52" AS lightweight configuration, with a dash-mounted dump switch and suspension indicator light.

Cab & Interior
Aero 118 BBC aluminum cab with Metton hood, finished with an 80" Ultraloft SLPR-Prestige interior in Sterling Gray and a thermal insulation package. Sleeper features a second bunk with ladder, walkthrough curtain, wardrobe cabinet shelves, coil spring mattress, RH baggage door, cabinet door and drawer package, LH full-height access door with tilting window, RH sleeper side tilting window, and a 1.8 ft³ refrigerator. Seating is Peterbilt LX driver and passenger, premium level, with air ride, high-back, and RH driver/LH passenger armrests. Multi-function steering wheel with PB logo, audio, and cruise controls, plus an adjustable tilt/telescoping column. One-piece curved windshield with a privacy curtain, standard power door locks and power windows. Climate comfort includes a D2 fuel-fired sleeper heater with digital controller and a combo fresh-air heater/air conditioner. Vanity mirrors on the inside sunvisors and an outside painted composite sunvisor. Peterbilt motorized, heated aero rear-view mirrors with integrated convex lenses, a look-down mirror over the passenger door, and black-housing rectangular hood mirrors. Infotainment includes satellite radio provisions, a ConcertClass AM/FM/WB radio with 3.5mm aux input, standard cab and sleeper speaker packages, Bluetooth phone/audio, dual USB charging ports, Cobra 29 CB radio provisions, and global telematics hardware with J1939 wiring provisions for telematics and ELD. A 15" digital instrument cluster displays engine oil temperature, air filter restriction pressure, tractor brake application air pressure, suspension air pressure (load), engine hourmeter, turbo boost, and engine percent torque. Lighting includes composite fender-mounted headlights with integral DRL/park/turn/side marker, five aero LED marker lights, LED oval stop/turn/tail/backup lights, and two LED load lights. Rounded out with electric windshield wipers (intermittent), a removable bugscreen behind the grille, and a fire extinguisher/triangle reflector kit.

Body & Equipment
Aero bumper (molded 3-piece, painted body color) with matching chassis aero fairings from quarter fender to BOS on both sides, front tire closeouts, a bumper lower aero fairing, EPIQ aero package (to BOS), and an aero closeout under the cab/sleeper sides. Aluminum battery box (LH under-cab) with a non-slip aftertreatment cab entry step. PB rear mudflaps on Fleetweng FB27 hangers (45°, painted) with Polyarmor black quarter fenders and Peterbilt logo flaps. Dual aluminum fuel tanks — 135-gal RH BOC and 110-gal LH BOC — with center fill, dual shutoff valves (dual draw/return), and anti-siphon devices, plus a 20-gal aero medium DEF tank mounted LH BOC. Air system includes a Bendix AD-HF air dryer with heater and coalescing filter, steel painted air tanks, a self-returning dash-mounted brake hand valve, and 12' straight air lines with two 7-way plugs.

Tires & Wheels
Front tires are 295/75R22.5, 16-ply (RY023); rear tires are 295/75R22.5, 16-ply (TY517 MC2), eight total. Wheels are Accuride 43644SP 22.5x8.25 aluminum, standard polish, front and rear.

Warranty & Protection
Backed by Peterbilt Class 8 standard coverage of 1 year/100,000 miles (160,000 km), PACCAR MX standard coverage of 2 years/250,000 miles (400,000 km)/6,250 hours, and a PACCAR MX base emissions warranty of 5 years/100,000 miles. Also includes a 5-year SmartLINQ remote diagnostics/OTA subscription for the PACCAR MX engine.