Firestone 4135 Coil-Rite Air Helper Spring Kit Rear for 98-25 Toyota 4Runner/FJ

Vehicle Fitment

• 1998-2025 Toyota 4Runner (2WD/4WD)
• 2007-2014 Toyota FJ Cruiser (2WD/4WD)
• 2013-2018 Lexus LX 570 (AWD)

Fitment Notes

• Designed as rear helper springs inside OEM coil springs
• Supports 500-1,000 lb rear load (max 1,000 lb per set)
• No drilling required; bolt-in with included hardware and manual inflation valves
• Not compatible with extra-lift aftermarket springs--requires stock coil inner diameter ~4.75"

Features

• Made of durable polyurethane--operates between -40°F to 180°F
• Variable-rate load support--acts like additional spring under load
• No air compressor needed; inflate like a tire (5-35 psi)
• Improve ride stability, reduce rear sag and enhance braking with trailer or heavy cargo
• Manual-control inflation kit included; can add Firestone Air Command system
• Rated for 1,000 lb load and includes magnetic drain plug
• Supported by Firestone's limited lifetime warranty on air springs, 2-year on hardware

Specifications

• Part Number: 4135 (W237604135)
• Air Spring Diameter: 4.75"; Length: 7.50"
• Load Capacity: 1,000 lb (set)
• Pressure Range: 5-35 psi
• Temperature Range: -40 °F to 180 °F
• Installation Time: ~1-2 hours

Included Components

• 2x Firestone Coil-Rite air springs
• 2x Mounting support plates
• Air line tubing and two manual inflation valves
• Installation instructions

Product Description

The Firestone 4135 Coil-Rite Rear Air Spring Kit is engineered to provide adjustable load support and improved ride quality for 1998-2025 Toyota 4Runner, 2007-2014 FJ Cruiser, and Lexus LX 570 platforms. These airbags fit inside the factory coil springs and operate between 5 and 35 psi to help maintain level suspension when carrying heavy loads or towing.

Constructed from high-quality polyurethane and rated for temperatures from -40°F to 180°F, this kit installs in about an hour without drilling, using included hardware and manual valves. With support for up to 1,000 lb and bolstered braking stability, rear ride height, and cornering control, it's an easy, effective upgrade backed by Firestone's lifetime air-spring warranty and 2-year hardware protection.