CTIS For Tractors And Trailers: What It Is And Why Retrofit
Central Tyre Inflation Systems (CTIS) let you inflate or deflate tyres to match load and speed. On the road you run higher pressures for stability and tread life. In the field you drop pressure to increase footprint, improve traction and cut compaction. The results are lower fuel use, smoother pulling and longer tyre life.
Retrofit CTIS suits mixed UK fleets across arable, dairy and contracting, and also construction or industrial yard movements. It is flexible, serviceable and available for most tractors and trailers. Factory-fit systems are sound but limited in choice and often cost more upfront. For tyre basics, see the ultimate guide to tractor tyres.
System Components And How CTIS Works
Air supply starts with a compressor (engine, PTO or 24V electric), feeding a receiver tank through an air dryer and filters. Dry, clean air protects valves and rotary seals and keeps the system reliable in UK weather.
An ECU and cab panel control solenoid valves using pressure sensors for each axle or wheel. At the hub, a rotary union feeds the tyre through guarded hoses and non-return valves for safety. Many systems coexist with TPMS. Fieldens OTR Ltd supplies compatible wheels and hardware under ISO 9001 processes; learn more about our manufacturing.
Tyre Pressure, Footprint And Soil Compaction: The Basics
Lowering pressure increases the contact patch, reducing ground pressure and slip. Typical starting bands are road 1.4–1.8 bar and field 0.6–1.0 bar, always set from the tyre maker’s load and speed tables.
IF/VF carcasses carry more load at a given pressure or the same load at a lower pressure. That reduces rutting on UK loams and clays, improves infiltration and protects soil structure. CTIS lets you hit the right pressure every time.
Plumbing Options: External Lines Vs Through-Axle For Tractors And Trailers
External hose-on-hub kits are quick to retrofit, easy to inspect and simple to service on farm. Through-axle air passages give tidy routing and protect lines, but are more involved to install. Both can be reliable when fitted correctly.
Single-line systems inflate and deflate through the same hose; dual-line adds speed and control. Guard hoses, avoid heat and moving parts, and use quick-release lines at trailer drawbars alongside brake services. Rotary unions need wheels drilled to spec; Fieldens OTR Ltd designs and builds bespoke wheels for CTIS.
This image was generated with AI and may not always represent the product or service exactly.
Control Strategies And Presets That Work On Farm
Operators use simple presets: Road, Field, Headland and Transport. Speed-linked lock-outs can prevent very low pressures above 40–50 km/h. Trailer load switches (loaded vs empty) keep tyres within their tables.
A headland preset cuts scuffing and improves pull when turning. Build in fail-safes so the system defaults to a safe pressure if a sensor or valve faults. Check pressures are stable before road travel.
Pressure Presets By Application (Typical UK Ranges)
Starting points: tractors (MFWD/duals) road 1.4–1.8 bar; field 0.6–1.0 bar; heavy draft 0.8–1.1 bar. Trailers: empty 1.0–1.4 bar; loaded 1.6–2.6+ bar depending on size and load. Flotation tyres in field often 0.5–0.8 bar.
These are guides only. Always set per Michelin, BKT or ATG data for the exact tyre, axle load and travel speed. CTIS makes switching fast, so you use the correct pressure, not a compromise.
Retrofit Assessment Checklist
Audit the vehicle: axle types, hub faces, hub cap depth for rotary unions, compressor flow and receiver space. Confirm alternator capacity for electric compressors and allow space for an air dryer.
Inspect tyres for condition, load index and speed symbol, and note any IF/VF fitments. Plan the cab controller position and wiring runs. Build a service plan for filters, leak checks, hose guards, torque and seals. For quotes or site surveys, contact Fieldens OTR Ltd.
Installation Steps And Common Pitfalls
Prepare the hub, remove and inspect the cap, then drill to the supplied template. Fit the rotary union with the correct sealant and torque. Route airlines with clamps and guards, clear of brakes, steering and suspension.
Pressure-test each circuit, soap-test all joints, calibrate sensors and record baseline leak-down. Typical pitfalls are misaligned unions (seal wear), hose chafe, neglected air dryer service and poor electrical grounds. Use professional fitting on heavy industrial or construction machines.
This image was generated with AI and may not always represent the product or service exactly.
ROI: Fuel, Time, Tyre Life And Soil Protection
CTIS can cut field fuel use by 5–12% by reducing slip and rolling resistance. Correct pressure extends tyre life by 15–25% and makes road travel smoother. Lower compaction protects 1–3% of yield on susceptible soils.
Example: a 200 hp tractor at 600 hours/year (60% field) with diesel at UK averages could save £1,000–£1,500 in fuel alone at 7% saving. Add tyre-life and downtime gains and payback in 12–24 months is realistic. See the cost of poor tyre care for context.
Polycoat Tyrefill, Puncture Strategy And CTIS Compatibility
CTIS needs an air cavity. Fully foam-filled tyres cannot be pressure-adjusted. Use filling on wheels or vehicles that do not require CTIS, or where puncture risk outweighs the benefits of pressure changes.
Fieldens OTR Ltd supplies Polycoat Tyrefill for high-risk industrial and yard work, and mixed fleets with non-CTIS machines. Compare options in why filling tyres with foam can save you money.
Example Builds And Specification Templates
150–220 hp tractor + 16–18 t grain trailer: IF/VF 650/65R38 rear, 540/65R28 front; trailer 560/60R22.5. Targets: tractor road 1.6–1.8 bar, field 0.7–0.9; trailer empty 1.2 bar; loaded 2.0–2.4. Compressor 300–450 l/min, 20–30 l tank.
Slurry tanker: flotation 750/60R30.5 at 0.6–0.8 bar in field, 1.8–2.4 bar on road. Construction dump trailer: 445/65R22.5 at 1.0–1.2 bar on site, 2.5+ bar on road. Notes: guarded external lines, protected unions, wheel drilling to template, and service access planned from day one.
Maintenance And Troubleshooting
Daily/weekly: confirm pressure stability, listen for leaks, inspect hoses and guards, and check compressor cut-in/out. Seasonal: replace dryer media and filters, test solenoids, update controller firmware and inspect rotary union seals.
Quick checks: slow fill (leaks, clogged filter, weak compressor), constant venting (stuck valve), sensor errors (wiring, ground). Good maintenance protects tyres and uptime across busy seasons.
Compliance, Safety And Documentation
Always respect tyre load ratings and speed symbols. Ensure pressures are stable before high-speed road use. CTIS can operate alongside TPMS if sensors are positioned and calibrated correctly.
Keep fitment records, preset sheets, risk assessments and notify your insurer. Fieldens OTR Ltd follows ISO 9001 with traceable wheel builds and documented CTIS-ready installations for compliance.
How Fieldens OTR Supports CTIS-Ready Wheels And Tyres
Fieldens OTR Ltd manufactures bespoke wheels to accept rotary unions, with precision drilling, correct offsets, quality paint and corrosion protection. We partner with Michelin, BKT and ATG to match tyres to the duty.
Our UK team delivers site survey, build, fitting and aftercare. We also supply Polycoat Tyrefill for non-CTIS roles. Expect practical advice, reliable products and personal service across agriculture, construction and industry.
FAQs
Can My Existing Tyres Work With CTIS?
Often yes, if load index and speed symbol allow the target pressures. IF/VF tyres unlock lower field pressures and better results. Always follow the tyre maker’s tables.
How Long Does A Retrofit Take?
Most tractor and trailer installs complete in one to two days per unit, depending on routing and hub work. Complex through-axle builds can take longer.
Will CTIS Affect Road Legality Or Insurance?
No, provided pressures meet tyre ratings and are stable before high-speed travel. Keep documentation and tell your insurer about the modification.
What Happens If A Hose Or Union Fails?
Non-return valves isolate the tyre and the system defaults to a safe state. You can continue at a reduced speed to a safe location for repair.
Do I Need A Bigger Compressor?
Small systems run on 24V compressors; larger fleets benefit from higher flow or engine/PTO-driven units. Size the compressor to tyre volume and desired fill time.
Can CTIS Work With Trailers That See Road And Field?
Yes. Use load switches (empty/loaded) and speed-based lock-outs. Quick-release lines at the drawbar make coupling simple alongside brake services.